Porting C++ OpenGL to PyOpenGL not rendering properly - python

I've been facing an issue for the past couple of days, and I still haven't been able to figure it out.. I'm trying to port a previous C++ Opengl project to PyOpengl, but I'm not able to get the object to render as it should. I'm simply trying to render a 3D grid model, which works in the original C++ code, but not in Python PyOpenGL.
What it should look like: (C++ OpenGL)
What it looks like (Python PyOpenGL)
This is the code I end up with in PyOpenGL :
import glfw
import glm
import numpy as np
from OpenGL.GL import *
import Shader
# Settings
SCR_WIDTH = 800
SCR_HEIGHT = 600
def framebuffer_size_callback(window, width, height):
if width != 0 and height != 0:
width = width
height = height
glViewport(0, 0, width, height)
def create_v_array():
vertexArray = []
indexArray = []
for x in range(-100, 102, 2):
# To draw lines across x axis from z = -1 to z = 1
vertexArray.append(glm.vec3(x / 100.0, 0.0, -1.0)) # Vertex position 1
vertexArray.append(glm.vec3(1.0, 1.0, 1.0)) # color for v1
vertexArray.append(glm.vec3(x / 100.0, 0.0, 1.0)) # Vertex position 2
vertexArray.append(glm.vec3(1.0, 1.0, 1.0)) # color for v2
for z in range(-100, 102, 2):
# To draw lines across z axis from x = -1 to x = 1
vertexArray.append(glm.vec3(-1.0, 0.0, z / 100.0)) # Vertex position 1
vertexArray.append(glm.vec3(1.0, 1.0, 1.0)) # color for v1
vertexArray.append(glm.vec3(1.0, 0.0, z / 100.0)) # Vertex position 2
vertexArray.append(glm.vec3(1.0, 1.0, 1.0)) # color for v2
for i in range(10000):
indexArray.append(i)
vao = GLuint()
vbo = GLuint()
ebo = GLuint()
vertexArray = np.array(vertexArray, dtype=np.float32)
indexArray = np.array(indexArray, dtype=np.float32)
# Bind vao
glGenVertexArrays(1, vao)
glBindVertexArray(vao)
# Upload Vertex Buffer (VBO) to the GPU, keep a reference to it (vertexBufferObject)
glGenBuffers(1, vbo)
glBindBuffer(GL_ARRAY_BUFFER, vbo)
glBufferData(GL_ARRAY_BUFFER, vertexArray.nbytes, vertexArray, GL_STATIC_DRAW)
# Upload Index Buffer (EBO) to the GPU, keep a reference to it (elementBufferObject)
glGenBuffers(1, ebo)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, indexArray.nbytes, indexArray, GL_STATIC_DRAW)
# Position
glVertexAttribPointer(0,
3,
GL_FLOAT,
GL_FALSE,
24,
None
)
glEnableVertexAttribArray(0)
# Color
glVertexAttribPointer(1,
3,
GL_FLOAT,
GL_FALSE,
24,
ctypes.c_void_p(12)
)
glEnableVertexAttribArray(1)
glBindBuffer(GL_ARRAY_BUFFER, 0)
glBindVertexArray(0)
return vao
def main():
# Initialize the library
#glfw.glewExperimental = GL_TRUE
if not glfw.init():
return
glfw.window_hint(glfw.CONTEXT_VERSION_MAJOR, 3)
glfw.window_hint(glfw.CONTEXT_VERSION_MINOR, 2)
glfw.window_hint(glfw.OPENGL_PROFILE, glfw.OPENGL_CORE_PROFILE)
glfw.window_hint(glfw.OPENGL_FORWARD_COMPAT, GL_TRUE)
# Create a windowed mode window and its OpenGL context
window = glfw.create_window(SCR_WIDTH, SCR_HEIGHT, "OpenGL", None, None)
if not window:
glfw.terminate()
return
# Make the window's context current
glfw.make_context_current(window)
glfw.set_framebuffer_size_callback(window, framebuffer_size_callback)
#glEnable(GL_DEPTH_TEST)
#glDepthFunc(GL_LESS)
shader = Shader.Shader("VertexShader.vsh", "FragmentShader.fsh")
vao = create_v_array()
glUseProgram(shader.ID)
# Loop until the user closes the window
while not glfw.window_should_close(window):
glClearColor(0.2, 0.3, 0.3, 1.0)
glClear(GL_COLOR_BUFFER_BIT)
glUseProgram(shader.ID)
glBindVertexArray(vao)
model = glm.mat4(1)
view = glm.mat4(1)
model = glm.rotate(model, glm.radians(15.0), glm.vec3(1.0, 0.0, 0.0))
view = glm.translate(view, glm.vec3(0.0, 0.0, -1.0))
projection = glm.perspective(glm.radians(45.0), (SCR_WIDTH/SCR_HEIGHT), 0.1, 100.0)
shader.set_mat4("model", model)
shader.set_mat4("view", view)
shader.set_mat4("projection", projection)
glBindVertexArray(vao)
glDrawElements(GL_LINES, 20000, GL_UNSIGNED_INT, None)
glfw.swap_buffers(window)
glfw.poll_events()
glfw.terminate()
if __name__ == "__main__":
main()
Custom Shader class:
class Shader:
def __init__(self, vertex_path, fragment_path):
vertex_code = get_file_content(vertex_path)
fragment_code = get_file_content(fragment_path)
vertex = glCreateShader(GL_VERTEX_SHADER)
glShaderSource(vertex, vertex_code)
glCompileShader(vertex)
result = glGetShaderiv(vertex, GL_COMPILE_STATUS)
if not (result):
print("Vertex shader ERROR!")
raise RuntimeError(glGetShaderInfoLog(vertex))
fragment = glCreateShader(GL_FRAGMENT_SHADER)
glShaderSource(fragment, fragment_code)
glCompileShader(fragment)
result2 = glGetShaderiv(fragment, GL_COMPILE_STATUS)
if not (result2):
print("Fragment shader ERROR!")
raise RuntimeError(glGetShaderInfoLog(vertex))
self.ID = glCreateProgram()
glAttachShader(self.ID, vertex)
glAttachShader(self.ID, fragment)
glLinkProgram(self.ID)
success = glGetProgramiv(self.ID, GL_LINK_STATUS)
if not success:
print("gad darn")
infolog = glGetProgramInfoLog(self.ID)
print("ERROR::SHADER::PROGRAM::LINKING_FAILED\n", infolog)
glDeleteShader(vertex)
glDeleteShader(fragment)
def set_mat4(self, name, matrix):
glUniformMatrix4fv(glGetUniformLocation(self.ID, name), 1, GL_FALSE, glm.value_ptr(matrix))
def use(self):
glUseProgram(self.ID)
# Helper Function
def get_file_content(file):
with open(file) as f:
content = f.read()
return content
glsl files:
Vertex Shader:
#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aColor;
out vec3 vertexColor;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main()
{
gl_Position = projection * view * model * vec4(aPos, 1.0);
vertexColor = aColor;
}
Fragment Shader:
#version 330 core
in vec3 vertexColor;
out vec4 FragColor;
void main()
{
FragColor = vec4(vertexColor.r, vertexColor.g, vertexColor.b, 1.0f);
}


The type of the indices must be integral instead of the floating point:
indexArray = np.array(indexArray, dtype=np.float32)
indexArray = np.array(indexArray, dtype=np.uint32)

Related

How to render text with PyOpenGL?

I'm learning modern openGL, and at this moment I'm facing trouble with rendering text. I'm following this tutorial which is in C++, but I'm trying to implement in python.
Here is my code:
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GL import shaders
import glfw
import freetype
import glm
import numpy as np
from PIL import Image
import math
import time
class CharacterSlot:
def __init__(self, texture, glyph):
self.texture = texture
self.textureSize = (glyph.bitmap.width, glyph.bitmap.rows)
if isinstance(glyph, freetype.GlyphSlot):
self.bearing = (glyph.bitmap_left, glyph.bitmap_top)
self.advance = glyph.advance.x
elif isinstance(glyph, freetype.BitmapGlyph):
self.bearing = (glyph.left, glyph.top)
self.advance = None
else:
raise RuntimeError('unknown glyph type')
def _get_rendering_buffer(xpos, ypos, w, h, zfix=0.0):
return np.asarray([
xpos, ypos - h, zfix, 0.0, 1.0,
xpos, ypos, zfix, 0.0, 0.0,
xpos + w, ypos, zfix, 1.0, 0.0,
xpos, ypos - h, zfix, 0.0, 1.0,
xpos + w, ypos, zfix, 1.0, 0.0,
xpos + w, ypos - h, zfix, 1.0, 1.0
], np.float32)
VERTEX_SHADER = """
#version 330 core
layout (location = 0) in vec4 vertex; // <vec2 pos, vec2 tex>
out vec2 TexCoords;
uniform mat4 projection;
void main()
{
gl_Position = projection * vec4(vertex.xy, 0.0, 1.0);
TexCoords = vertex.zw;
}
"""
FRAGMENT_SHADER = """
#version 330 core
in vec2 TexCoords;
out vec4 color;
uniform sampler2D text;
uniform vec3 textColor;
void main()
{
vec4 sampled = vec4(1.0, 1.0, 1.0, texture(text, TexCoords).r);
color = vec4(textColor, 1.0) * sampled;
}
"""
shaderProgram = None
Characters = dict()
VBO = None
VAO = None
def initliaze():
global VERTEXT_SHADER
global FRAGMENT_SHADER
global shaderProgram
global Characters
global VBO
global VAO
#compiling shaders
vertexshader = shaders.compileShader(VERTEX_SHADER, GL_VERTEX_SHADER)
fragmentshader = shaders.compileShader(FRAGMENT_SHADER, GL_FRAGMENT_SHADER)
#creating shaderProgram
shaderProgram = shaders.compileProgram(vertexshader, fragmentshader)
#get projection
#problem
shader_projection = glGetUniformLocation(shaderProgram, "projection")
projection = glm.ortho(0.0,640,0.0,640)
glUniformMatrix4fv(shader_projection, 1, GL_FALSE, glm.value_ptr(projection));
#disable byte-alignment restriction
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
face = freetype.Face("Vera.ttf")
face.set_char_size( 48*64 )
#load first 128 characters of ASCII set
for i in range(0,128):
face.load_char(chr(i))
glyph = face.glyph
#generate texture
texture = glGenTextures(1)
glBindTexture(GL_TEXTURE_2D, texture)
glTexImage2D(GL_TEXTURE_2D,
0,
GL_RGB,
glyph.bitmap.width, glyph.bitmap.rows,
0,
GL_RGB,
GL_UNSIGNED_BYTE,
glyph.bitmap.buffer)
#texture options
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
#now store character for later use
Characters[chr(i)] = CharacterSlot(texture,glyph)
glBindTexture(GL_TEXTURE_2D, 0);
#configure VAO/VBO for texture quads
VAO = glGenVertexArrays(1)
glBindVertexArray(VAO)
VBO = glGenBuffers(1);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, 6 * 4, None, GL_DYNAMIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4, 0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
def render_text(window,text,x,y,scale,color):
global shaderProgram
global Characters
global VBO
global VAO
face = freetype.Face("Vera.ttf")
face.set_char_size(48*64)
glUniform3f(glGetUniformLocation(shaderProgram, "textColor"),
color[0]/255,color[1]/255,color[2]/255)
glActiveTexture(GL_TEXTURE0);
for c in text:
ch = Characters[c]
w,h = ch.textureSize
w = w*scale
h = w*scale
vertices = _get_rendering_buffer(x,y,w,h)
#render glyph texture over quad
glBindTexture(GL_TEXTURE_2D, ch.texture);
#update content of VBO memory
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferSubData(GL_ARRAY_BUFFER, 0, len(vertices), vertices)
glBindBuffer(GL_ARRAY_BUFFER, 0);
#render quad
glDrawArrays(GL_TRIANGLES, 0, 6);
#now advance cursors for next glyph (note that advance is number of 1/64 pixels)
x += (ch.advance+6)*scale;
glBindVertexArray(0);
glBindTexture(GL_TEXTURE_2D, 0);
glfwSwapBuffers(window);
glfwPollEvents();
def main():
glfw.init()
window = glfw.create_window(640, 640,"EXAMPLE PROGRAM",None,None)
glfw.make_context_current(window)
initliaze()
while not glfw.window_should_close(window):
glfw.poll_events()
glClearColor(0,0,0,1);
glClear(GL_COLOR_BUFFER_BIT);
render_text(window,'hello',1,1,1,(100,100,100))
glfw.terminate()
if __name__ == '__main__':
main()
I'm facing trouble in two portion so far I can understand. The first problem in initliaze(), error raised for the following portion.
shader_projection = glGetUniformLocation(shaderProgram, "projection")
projection = glm.ortho(0.0,640,0.0,640)
glUniformMatrix4fv(shader_projection, 1, GL_FALSE, glm.value_ptr(projection));
I've commented out the above portion to ignore. The second problem is in render_text() function, error raised for the following portion.
glUniform3f(glGetUniformLocation(shaderProgram, "textColor"),
color[0]/255,color[1]/255,color[2]/255)
There could be problems in many more places. I don't understand that why text rendering will be so difficult. What am I missing here?

You missed to install the shader program by glUseProgram:
shaderProgram = shaders.compileProgram(vertexshader, fragmentshader)
glUseProgram(shaderProgram) # <---
The 2nd argument to glBufferData and the 3rd argument of glBufferSubData is the size in bytes:
glBufferData(GL_ARRAY_BUFFER, 6 * 4, None, GL_DYNAMIC_DRAW)
glBufferData(GL_ARRAY_BUFFER, 6 * 4 * 4, None, GL_DYNAMIC_DRAW)
glBufferSubData(GL_ARRAY_BUFFER, 0, len(vertices), vertices)
glBufferSubData(GL_ARRAY_BUFFER, 0, vertices.nbytes, vertices)
The vertex attribute consist of a 2 dimension vertex coordinate (x, y) and a 2 dimensional texture coordinate. Remove the wird zfix from the array of vertex attribute data. Furthermore you have to flip the 2nd component of the texture coordinates (otherwise the text is upside down)
def _get_rendering_buffer(xpos, ypos, w, h, zfix=0.0):
return np.asarray([
xpos, ypos - h, 0, 0,
xpos, ypos, 0, 1,
xpos + w, ypos, 1, 1,
xpos, ypos - h, 0, 0,
xpos + w, ypos, 1, 1,
xpos + w, ypos - h, 1, 0
], np.float32)
The stride argument of glVertexAttribIPointer has to be specified in bytes. If stride is 0, the generic vertex attributes are understood to be tightly packed in the array. Hence in your case stride has to be 16 or 0:
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4, 0)
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, None)
face.load_char(chr(i)) generates a image with on color channel (1 byte per pixel). Use the internal format and format GL_RED rather than GL_RGB for generating the 2 dimensional texture image:
glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, glyph.bitmap.width, glyph.bitmap.rows, 0,
GL_RED, GL_UNSIGNED_BYTE, glyph.bitmap.buffer)
You have to bind the vertex array, before drawing the text:
glBindVertexArray(VAO)
for c in text:
# [...]
glDrawArrays(GL_TRIANGLES, 0, 6)
There is typo when you increment x, you have to use the >>-operator rather than the +-operator:
x += (ch.advance+6)*scale
x += (ch.advance>>6)*scale
and another typo when you compute h:
h = w*scale
h = h*scale
You have to enable alpha blending:
glEnable(GL_BLEND)
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
In NDC (normalized device coordinates) the left bottom is (-1, -1) and the right top is (1, 1). Set the orthographic projection in that way, that the top left of the window is at (0, 0):
projection = glm.ortho(0.0,640,0.0,640)
projection = glm.ortho(0, 640, 640, 0)
The reference point of the text is at the bottom. Hence you have to set a x coordinate greater than the text height:
render_text(window,'hello',1,1,1,(100,100,100))
render_text(window,'hello', 20, 50, 1, (255, 100, 100))
See the complete example (I've used a different font):
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GL import shaders
import glfw
import freetype
import glm
import numpy as np
from PIL import Image
import math
import time
fontfile = "Vera.ttf"
#fontfile = r'C:\source\resource\fonts\gnu-freefont_freesans\freesans.ttf'
class CharacterSlot:
def __init__(self, texture, glyph):
self.texture = texture
self.textureSize = (glyph.bitmap.width, glyph.bitmap.rows)
if isinstance(glyph, freetype.GlyphSlot):
self.bearing = (glyph.bitmap_left, glyph.bitmap_top)
self.advance = glyph.advance.x
elif isinstance(glyph, freetype.BitmapGlyph):
self.bearing = (glyph.left, glyph.top)
self.advance = None
else:
raise RuntimeError('unknown glyph type')
def _get_rendering_buffer(xpos, ypos, w, h, zfix=0.0):
return np.asarray([
xpos, ypos - h, 0, 0,
xpos, ypos, 0, 1,
xpos + w, ypos, 1, 1,
xpos, ypos - h, 0, 0,
xpos + w, ypos, 1, 1,
xpos + w, ypos - h, 1, 0
], np.float32)
VERTEX_SHADER = """
#version 330 core
layout (location = 0) in vec4 vertex; // <vec2 pos, vec2 tex>
out vec2 TexCoords;
uniform mat4 projection;
void main()
{
gl_Position = projection * vec4(vertex.xy, 0.0, 1.0);
TexCoords = vertex.zw;
}
"""
FRAGMENT_SHADER = """
#version 330 core
in vec2 TexCoords;
out vec4 color;
uniform sampler2D text;
uniform vec3 textColor;
void main()
{
vec4 sampled = vec4(1.0, 1.0, 1.0, texture(text, TexCoords).r);
color = vec4(textColor, 1.0) * sampled;
}
"""
shaderProgram = None
Characters = dict()
VBO = None
VAO = None
def initliaze():
global VERTEXT_SHADER
global FRAGMENT_SHADER
global shaderProgram
global Characters
global VBO
global VAO
#compiling shaders
vertexshader = shaders.compileShader(VERTEX_SHADER, GL_VERTEX_SHADER)
fragmentshader = shaders.compileShader(FRAGMENT_SHADER, GL_FRAGMENT_SHADER)
#creating shaderProgram
shaderProgram = shaders.compileProgram(vertexshader, fragmentshader)
glUseProgram(shaderProgram)
#get projection
#problem
shader_projection = glGetUniformLocation(shaderProgram, "projection")
projection = glm.ortho(0, 640, 640, 0)
glUniformMatrix4fv(shader_projection, 1, GL_FALSE, glm.value_ptr(projection))
#disable byte-alignment restriction
glPixelStorei(GL_UNPACK_ALIGNMENT, 1)
face = freetype.Face(fontfile)
face.set_char_size( 48*64 )
#load first 128 characters of ASCII set
for i in range(0,128):
face.load_char(chr(i))
glyph = face.glyph
#generate texture
texture = glGenTextures(1)
glBindTexture(GL_TEXTURE_2D, texture)
glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, glyph.bitmap.width, glyph.bitmap.rows, 0,
GL_RED, GL_UNSIGNED_BYTE, glyph.bitmap.buffer)
#texture options
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
#now store character for later use
Characters[chr(i)] = CharacterSlot(texture,glyph)
glBindTexture(GL_TEXTURE_2D, 0)
#configure VAO/VBO for texture quads
VAO = glGenVertexArrays(1)
glBindVertexArray(VAO)
VBO = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, VBO)
glBufferData(GL_ARRAY_BUFFER, 6 * 4 * 4, None, GL_DYNAMIC_DRAW)
glEnableVertexAttribArray(0)
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, None)
glBindBuffer(GL_ARRAY_BUFFER, 0)
glBindVertexArray(0)
def render_text(window,text,x,y,scale,color):
global shaderProgram
global Characters
global VBO
global VAO
face = freetype.Face(fontfile)
face.set_char_size(48*64)
glUniform3f(glGetUniformLocation(shaderProgram, "textColor"),
color[0]/255,color[1]/255,color[2]/255)
glActiveTexture(GL_TEXTURE0)
glEnable(GL_BLEND)
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
glBindVertexArray(VAO)
for c in text:
ch = Characters[c]
w, h = ch.textureSize
w = w*scale
h = h*scale
vertices = _get_rendering_buffer(x,y,w,h)
#render glyph texture over quad
glBindTexture(GL_TEXTURE_2D, ch.texture)
#update content of VBO memory
glBindBuffer(GL_ARRAY_BUFFER, VBO)
glBufferSubData(GL_ARRAY_BUFFER, 0, vertices.nbytes, vertices)
glBindBuffer(GL_ARRAY_BUFFER, 0)
#render quad
glDrawArrays(GL_TRIANGLES, 0, 6)
#now advance cursors for next glyph (note that advance is number of 1/64 pixels)
x += (ch.advance>>6)*scale
glBindVertexArray(0)
glBindTexture(GL_TEXTURE_2D, 0)
glfw.swap_buffers(window)
glfw.poll_events()
def main():
glfw.init()
window = glfw.create_window(640, 640,"EXAMPLE PROGRAM",None,None)
glfw.make_context_current(window)
initliaze()
while not glfw.window_should_close(window):
glfw.poll_events()
glClearColor(0,0,0,1)
glClear(GL_COLOR_BUFFER_BIT)
render_text(window,'hello', 20, 50, 1, (255, 100, 100))
glfw.terminate()
if __name__ == '__main__':
main()
See also FreeType / OpenGL text rendering

Using PyOpenGL, how do you apply instancing on an .obj file?

I am trying to apply instancing on a object (.obj) file by following the example on Learn Opengl - Instancing.
My question is actually twofold:
1) How to apply instancing on .obj files? (I think I'm almost there)
2) As I understand, to use instancing it is necessary to store the .obj file in a vertex array buffer (VAO), and therefore need help setting the materials and textures for the .obj file. That is if my assumption is true? (For now I just assigned the object to a solid white colour.)
What I have done so far:
I use Pywavefront to load the .obj file but I'm not stuck on it if another obj loader is needed.
Setting locations of where to place the object:
#Locations
vertices = [[-33.64413, 0.0, 19.03057], [-33.64818, 0.0, 19.0219],
[-33.64921, 0.0, 19.011],[-33.64913, 0.0, 19.03027], [-33.69828, 0.0, 19.0219],
[-33.64991, 0.0, 19.021]]
self.vertices = numpy.array(vertices, dtype='f')
Loading OBJ and collecting vertices and faces (indices):
obj_file = pywavefront.Wavefront('OBJ_PINS/Mcdonalds.obj', collect_faces=True)
obj_vertices = numpy.array(obj_file.vertices, dtype='f')
faces_list = []
for mesh in obj_file.mesh_list:
for face in mesh.faces:
faces_list.append(face)
obj_ind = numpy.array(faces_list, dtype=numpy.int32)
I then create a Vertex Array Object (VAO) with the necessary vertex buffer object (VBO):
VAOs = glGenVertexArrays(1)
glBindVertexArray(VAOs)
# Vertex Buffer Object
VBO = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, VBO)
glBufferData(GL_ARRAY_BUFFER, obj_vertices.nbytes, obj_vertices, GL_STATIC_DRAW)
# Element Buffer Object
EBO = glGenBuffers(1)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, obj_ind.nbytes, obj_ind, GL_STATIC_DRAW)
# vertices
glEnableVertexAttribArray(0)
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, obj_vertices.itemsize * 3, ctypes.c_void_p(0))
Transforming and storing the object for instancing:
# instance locations
amount = len(self.vertices)
#List storing the same object in different places
modelMatrices = []
#Storring the objects in a list
for i in range(0, amount):
model_o = glm.mat4(1.0)
model_o = glm.translate(model_o, glm.vec3(self.vertices[i][0], self.vertices[i][1], self.vertices[i][2]))
model_o = glm.scale(model_o, glm.vec3(0.0001, 0.0001, 0.0001))
modelMatrices.append(model_o)
The interesting part, instancing the object to different places:
#Create VBO for instancing
instanceVBO = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, instanceVBO)
glBufferData(GL_ARRAY_BUFFER, glm.sizeof(glm.mat4), glm.value_ptr(modelMatrices[0]), GL_STATIC_DRAW)
#Bind each vertex attrib array of matrices (4 vectors in Matrix)
glEnableVertexAttribArray(3)
glVertexAttribPointer(3, 4, GL_FLOAT, GL_FALSE, glm.sizeof(glm.mat4), ctypes.c_void_p(0))
glEnableVertexAttribArray(4)
glVertexAttribPointer(4, 4, GL_FLOAT, GL_FALSE, glm.sizeof(glm.mat4), ctypes.c_void_p(glm.sizeof(glm.vec4)))
glEnableVertexAttribArray(5)
glVertexAttribPointer(5, 4, GL_FLOAT, GL_FALSE, glm.sizeof(glm.mat4), ctypes.c_void_p((2 * glm.sizeof(glm.vec4))))
glEnableVertexAttribArray(6)
glVertexAttribPointer(6, 4, GL_FLOAT, GL_FALSE, glm.sizeof(glm.mat4), ctypes.c_void_p((3 * glm.sizeof(glm.vec4))))
#Set instancing
glVertexAttribDivisor(3, 1)
glVertexAttribDivisor(4, 1)
glVertexAttribDivisor(5, 1)
glVertexAttribDivisor(6, 1)
#End VAO
glBindVertexArray(0)
The shaders:
self.vertex_obj = """
# version 330
in layout(location = 0) vec3 aPos;
in layout (location = 3) mat4 instanceMatrix;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main()
{
gl_Position = projection * view * instanceMatrix * vec4(aPos, 1.0);
}
"""
self.fragment_obj = """
#version 330
out vec4 FragColor;
void main()
{
FragColor = vec4(1.0,1.0,1.0, 1.0);
}
"""
When I draw the object in the drawing loop I only see one object and not 6:
glBindVertexArray(VAOs)
glDrawElementsInstanced(GL_TRIANGLES, len(obj_ind)*3, GL_UNSIGNED_INT, None, amount)
glBindVertexArray(0)
What I think is wrong:
I need to call the whole list of matrices to be drawn in the instanced glBufferData but don't know how to do that.
Should it change to something like:
glBufferData(GL_ARRAY_BUFFER, amount * glm.sizeof(glm.mat4), glm.value_ptr(modelMatrices[?]), GL_STATIC_DRAW)
FULL CODE
import numpy
import glfw
from OpenGL.GL import *
from OpenGL.GL.shaders import compileProgram, compileShader
import pyrr
import glm
from pyrr import matrix44
from math import sin, cos, radians
from OBJ_Loader import*
import pywavefront
class threeD_viewer():
def __init__(self):
vertices = [[-33.64413, 0.0, 19.03057], [-33.64818, 0.0, 19.0219],
[-33.64921, 0.0, 19.011],[-33.64913, 0.0, 19.03027], [-33.69828, 0.0, 19.0219],
[-33.64991, 0.0, 19.021]]
self.vertices = numpy.array(vertices, dtype='f')
self.cam = Camera(self.vertices[0][0], self.vertices[0][2])
self.WIDTH, self.HEIGHT = 1280, 720
self.lastX, self.LastY = self.WIDTH / 2, self.HEIGHT / 2
self.first_mouse = True
self.forward, self.backward, self.right, self.left, self.up, self.down = False, False, False, False, False, False
self.x_start, self.y_start = self.vertices[0][0], self.vertices[0][2]
self.vertex_obj = """
# version 330
in layout(location = 0) vec3 aPos;
in layout (location = 3) mat4 instanceMatrix;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main()
{
gl_Position = projection * view * instanceMatrix * vec4(aPos, 1.0);
}
"""
self.fragment_obj = """
#version 330
out vec4 FragColor;
void main()
{
FragColor = vec4(1.0,1.0,1.0, 1.0);
}
"""
self.main()
# the keyboard input callback
def key_input_clb(self, window, key, scancode, action, mode):
if key == glfw.KEY_ESCAPE and action == glfw.PRESS:
glfw.set_window_should_close(window, True)
if key == glfw.KEY_W and action == glfw.PRESS:
self.forward = True
elif key == glfw.KEY_W and action == glfw.RELEASE:
self.forward = False
if key == glfw.KEY_S and action == glfw.PRESS:
self.backward = True
elif key == glfw.KEY_S and action == glfw.RELEASE:
self.backward = False
if key == glfw.KEY_A and action == glfw.PRESS:
self.left = True
elif key == glfw.KEY_A and action == glfw.RELEASE:
self.left = False
if key == glfw.KEY_D and action == glfw.PRESS:
self.right = True
elif key == glfw.KEY_D and action == glfw.RELEASE:
self.right = False
if key == glfw.KEY_Q and action == glfw.PRESS:
self.up = True
elif key == glfw.KEY_Q and action == glfw.RELEASE:
self.up = False
if key == glfw.KEY_E and action == glfw.PRESS:
self.down = True
elif key == glfw.KEY_E and action == glfw.RELEASE:
self.down = False
def do_movement(self):
if self.forward:
self.cam.process_keyboard("FORWARD", 0.000008)
if self.backward:
self.cam.process_keyboard("BACKWARD", 0.000008)
if self.right:
self.cam.process_keyboard("RIGHT", 0.000008)
if self.left:
self.cam.process_keyboard("LEFT", 0.000008)
if self.up:
self.cam.process_keyboard("UP", 0.000008)
if self.down:
self.cam.process_keyboard("DOWN", 0.000008)
def mmouse_look_clb(self, window, xpos, ypos):
if self.first_mouse:
self.lastX = xpos
self.lastY = ypos
self.first_mouse = False
xoffset = xpos - self.lastX
yoffset = self.lastY - ypos
self.lastX = xpos
self.lastY = ypos
self.cam.process_mouse_movement(xoffset, yoffset)
def window_resize(self, window, width, height):
glViewport(0, 0, width, height)
projection = pyrr.matrix44.create_perspective_projection_matrix(45, width / height, 0.0001, 100)
proj_loc = glGetUniformLocation(self.shader_obj, "projection")
glUniformMatrix4fv(proj_loc, 1, GL_FALSE, projection)
def main(self):
# initializing glfw library
if not glfw.init():
raise Exception("glfw can not be initialized!")
# creating the window
window = glfw.create_window(self.WIDTH, self.HEIGHT, "My OpenGL window", None, None)
# check if window was created
if not window:
glfw.terminate()
raise Exception("glfw window can not be created!")
# set window's position
glfw.set_window_pos(window, 400, 200)
# set the callback function for window resize
glfw.set_window_size_callback(window, self.window_resize)
glfw.set_cursor_pos_callback(window, self.mmouse_look_clb)
glfw.set_input_mode(window, glfw.CURSOR, glfw.CURSOR_DISABLED)
glfw.set_key_callback(window, self.key_input_clb)
# make the context current
glfw.make_context_current(window)
self.shader_obj = compileProgram(compileShader(self.vertex_obj, GL_VERTEX_SHADER),
compileShader(self.fragment_obj, GL_FRAGMENT_SHADER))
obj_file = pywavefront.Wavefront('OBJ_PINS/Mcdonalds.obj', collect_faces=True)
obj_vertices = numpy.array(obj_file.vertices, dtype='f')
faces_list = []
for mesh in obj_file.mesh_list:
for face in mesh.faces:
faces_list.append(face)
obj_ind = numpy.array(faces_list, dtype=numpy.int32)
VAOs = glGenVertexArrays(1)
glBindVertexArray(VAOs)
# Vertex Buffer Object
VBO = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, VBO)
glBufferData(GL_ARRAY_BUFFER, obj_vertices.nbytes, obj_vertices, GL_STATIC_DRAW)
# Element Buffer Object
EBO = glGenBuffers(1)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, obj_ind.nbytes, obj_ind, GL_STATIC_DRAW)
# vertices
glEnableVertexAttribArray(0)
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, obj_vertices.itemsize * 3, ctypes.c_void_p(0))
# instance locations
amount = len(self.vertices)
#List storing the same object in different places
modelMatrices = []
#Storring the objects in a list
for i in range(0, amount):
model_o = glm.mat4(1.0)
model_o = glm.translate(model_o, glm.vec3(self.vertices[i][0], self.vertices[i][1], self.vertices[i][2]))
model_o = glm.scale(model_o, glm.vec3(0.0001, 0.0001, 0.0001))
modelMatrices.append(model_o)
#Create VBO for instancing
instanceVBO = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, instanceVBO)
glBufferData(GL_ARRAY_BUFFER, glm.sizeof(glm.mat4), glm.value_ptr(modelMatrices[0]), GL_STATIC_DRAW)
#Bind each vertex attrib array of matrices (4 vectors in Matrix)
glEnableVertexAttribArray(3)
glVertexAttribPointer(3, 4, GL_FLOAT, GL_FALSE, glm.sizeof(glm.mat4), ctypes.c_void_p(0))
glEnableVertexAttribArray(4)
glVertexAttribPointer(4, 4, GL_FLOAT, GL_FALSE, glm.sizeof(glm.mat4), ctypes.c_void_p(glm.sizeof(glm.vec4)))
glEnableVertexAttribArray(5)
glVertexAttribPointer(5, 4, GL_FLOAT, GL_FALSE, glm.sizeof(glm.mat4), ctypes.c_void_p((2 * glm.sizeof(glm.vec4))))
glEnableVertexAttribArray(6)
glVertexAttribPointer(6, 4, GL_FLOAT, GL_FALSE, glm.sizeof(glm.mat4), ctypes.c_void_p((3 * glm.sizeof(glm.vec4))))
#Set instancing
glVertexAttribDivisor(3, 1)
glVertexAttribDivisor(4, 1)
glVertexAttribDivisor(5, 1)
glVertexAttribDivisor(6, 1)
#End VAO
glBindVertexArray(0)
glClearColor(0, 0.1, 0.1, 1)
glEnable(GL_DEPTH_TEST)
glEnable(GL_BLEND)
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
#projection = pyrr.matrix44.create_perspective_projection_matrix(45, self.WIDTH / self.HEIGHT, 0.0001, 1000)
projection = glm.perspective(glm.radians(45.0), self.WIDTH / self.HEIGHT, 0.0001, 1000)
glUseProgram(self.shader_obj)
view_loc_obj = glGetUniformLocation(self.shader_obj, "view")
proj_loc_obj = glGetUniformLocation(self.shader_obj, "projection")
model_loc_obj = glGetUniformLocation(self.shader_obj, "model")
glUniformMatrix4fv(proj_loc_obj, 1, GL_FALSE, glm.value_ptr(projection))
glUseProgram(0)
# the main application loop
while not glfw.window_should_close(window):
glfw.poll_events()
self.do_movement()
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
glUseProgram(self.shader_obj)
view = self.cam.get_view_matrix()
glUniformMatrix4fv(proj_loc_obj, 1, GL_FALSE, glm.value_ptr(projection))
glUniformMatrix4fv(view_loc_obj, 1, GL_FALSE, view)
glBindVertexArray(VAOs)
glDrawElementsInstanced(GL_TRIANGLES, len(obj_ind)*3, GL_UNSIGNED_INT, None, amount)
glBindVertexArray(0)
glUseProgram(0)
glfw.swap_buffers(window)
# terminate glfw, free up allocated resources
glfw.terminate()
class Camera:
def __init__(self, xstart, ystart):
self.camera_pos = glm.vec3(xstart+0.005, 0, ystart+0.01)
#self.camera_pos = glm.vec3(0, 0, 0)
print(xstart+0.005)
print(ystart+0.01)
self.camera_front = glm.vec3(0.0, 0.0, -200.0)
self.camera_up = glm.vec3(0.0, 1.0, 0.0)
self.camera_right = glm.vec3(1.0, 0.0, 0.0)
self.mouse_sensitivity = 0.25
self.jaw = -90.0
self.pitch = 0.0
def get_view_matrix(self):
return matrix44.create_look_at(self.camera_pos, self.camera_pos + self.camera_front, self.camera_up)
def process_mouse_movement(self, xoffset, yoffset, constrain_pitch=True):
xoffset *= self.mouse_sensitivity
yoffset *= self.mouse_sensitivity
self.jaw += xoffset
self.pitch += yoffset
if constrain_pitch:
if self.pitch > 45:
self.pitch = 45
if self.pitch < -45:
self.pitch = -45
self.update_camera_vectors()
def update_camera_vectors(self):
front = glm.vec3(0.0, 0.0, 0.0)
front.x = cos(radians(self.jaw)) * cos(radians(self.pitch))
front.y = sin(radians(self.pitch))
front.z = sin(radians(self.jaw)) * cos(radians(self.pitch))
self.camera_front = glm.normalize(front)
self.camera_right = glm.normalize(glm.cross(self.camera_front, glm.vec3(0.0, 1.0, 0.0)))
#self.camera_up = glm.normalize(glm.cross(self.camera_right, self.camera_front))
# Camera method for the WASD movement
def process_keyboard(self, direction, velocity):
if direction == "FORWARD":
self.camera_pos += self.camera_front * velocity
if direction == "BACKWARD":
self.camera_pos -= self.camera_front * velocity
if direction == "LEFT":
self.camera_pos -= self.camera_right * velocity
if direction == "RIGHT":
self.camera_pos += self.camera_right * velocity
if direction == "UP":
self.camera_pos += self.camera_up * velocity
if direction == "DOWN":
self.camera_pos -= self.camera_up * velocity
threeD_viewer()
Update
Instancing works now. The solution was to store a list of the vectors rather than the glm.mat4 objects:
# instance locations
amount = len(self.vertices)
#List storing the same object in different places
modelMatrices = []
#Storring the objects in a list
for i in range(0, amount):
mod_list = []
model_o = glm.mat4(1.0)
model_o = glm.translate(model_o, glm.vec3(self.vertices[i][0], self.vertices[i][1], self.vertices[i][2]))
for i in range(4):
for j in range(4):
mod_list.append(model_o[i][j])
modelMatrices.append(mod_list)
modelMatrices = numpy.array(modelMatrices, dtype ="f")
print(modelMatrices.shape)
#Create VBO for instancing
instanceVBO = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, instanceVBO)
glBufferData(GL_ARRAY_BUFFER, amount* glm.sizeof(glm.mat4), modelMatrices, GL_STATIC_DRAW)

How to get clip distances and textures on green dragon rendering

The source is of a green dragon rendering. My question is how to get the clip distances working on it? Also, the textures are not appearing as the expected output. Any ideas what can be modified in the source code to render the program as expected?
Update: With the excellent help and superb answers of Rabbid76 the clip distance is working and texture loading is working! Thank You.
Bonus example: clipdistance_torus_package.zip a clip distance example with a torus and textures!
Expected output:
Files to run: clipdistance_dragon.zip
#!/usr/bin/python3
import sys
import time
import ctypes
fullscreen = True
sys.path.append("./shared")
from sbmloader import SBMObject # location of sbm file format loader
from ktxloader import KTXObject
from sbmath import m3dDegToRad, m3dRadToDeg, m3dTranslateMatrix44, m3dRotationMatrix44, m3dMultiply, m3dOrtho, m3dPerspective, rotation_matrix, translate, m3dScaleMatrix44, \
scale, m3dLookAt, normalize
try:
from OpenGL.GLUT import *
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.raw.GL.ARB.vertex_array_object import glGenVertexArrays, glBindVertexArray
except:
print ('''
ERROR: PyOpenGL not installed properly.
''')
sys.exit()
import numpy as np
from math import cos, sin
identityMatrix = [1,0,0,0, 0,1,0,0, 0,0,1,0, 0,0,0,1]
myobject = SBMObject()
render_program = GLuint(0)
paused = False
class uniforms:
proj_matrix = GLint(0)
mv_matrix = GLint(0)
clip_plane = GLint(0)
clip_sphere = GLint(0)
uniform = uniforms()
def shader_load(filename, shader_type):
result = GLuint(0)
with open ( filename, "rb") as data:
result = glCreateShader(shader_type)
glShaderSource(result, data.read() )
glCompileShader(result)
if not glGetShaderiv(result, GL_COMPILE_STATUS):
print( 'compile error:' )
print( glGetShaderInfoLog(result) )
return result
def link_from_shaders(shaders, shader_count, delete_shaders, check_errors=False):
program = GLuint(0)
program = glCreateProgram()
for i in range(0, shader_count):
glAttachShader(program, shaders[i])
glLinkProgram(program)
if not glGetProgramiv(program, GL_LINK_STATUS):
print( 'link error:' )
print( glGetProgramInfoLog(program) )
if (delete_shaders):
for i in range(0, shader_count):
glDeleteShader(shaders[i])
return program
def load_shaders():
global render_program
global uniform
if (render_program):
glDeleteProgram(render_program);
shaders = [
shader_load("render.vs.glsl", GL_VERTEX_SHADER),
shader_load("render.fs.glsl", GL_FRAGMENT_SHADER)
]
render_program = link_from_shaders(shaders, 2, True)
uniform.proj_matrix = glGetUniformLocation(render_program, "proj_matrix");
uniform.mv_matrix = glGetUniformLocation(render_program, "mv_matrix");
uniform.clip_plane = glGetUniformLocation(render_program, "clip_plane");
uniform.clip_sphere = glGetUniformLocation(render_program, "clip_sphere");
tex_dragon=None
class Scene:
def __init__(self, width, height):
global myobject, tex_dragon
myobject.load("dragon.sbm");
load_shaders()
ktxobj = KTXObject()
tex_dragon = ktxobj.ktx_load("pattern1.ktx")
def display(self):
global paused
currentTime = time.time()
black = [ 0.0, 0.0, 0.0, 0.0 ]
one = 1.0
last_time = 0.0
total_time = 0.0
if (not paused):
total_time += (currentTime - last_time)
last_time = currentTime
f = total_time
glClearBufferfv(GL_COLOR, 0, black)
glClearBufferfv(GL_DEPTH, 0, one)
glUseProgram(render_program)
proj_matrix = (GLfloat * 16)(*identityMatrix)
proj_matrix = m3dPerspective(m3dDegToRad(50.0), float(self.width) / float(self.height), 0.1, 1000.0)
T1 = (GLfloat * 16)(*identityMatrix)
m3dTranslateMatrix44(T1, 0.0, 0.0, -15.0)
RY = (GLfloat * 16)(*identityMatrix)
m3dRotationMatrix44(RY, f * 0.34, 0.0, 1.0, 0.0)
T2 = (GLfloat * 16)(*identityMatrix)
m3dTranslateMatrix44(T2, 0.0, -4.0, 0.0)
mv_matrix = (GLfloat * 16)(*identityMatrix)
mv_matrix = m3dMultiply(T1, m3dMultiply(RY, T2))
RX = (GLfloat * 16)(*identityMatrix)
m3dRotationMatrix44(RX, f * 6.0, 1.0, 0.0, 0.0)
RY = (GLfloat * 16)(*identityMatrix)
m3dRotationMatrix44(RY, f * 7.3, 0.0, 1.0, 0.0)
plane_matrix = (GLfloat * 16)(*identityMatrix)
plane_matrix = m3dMultiply(RX , RY )
plane = plane_matrix[0:4]
plane[3] = 0
plane = normalize(plane)
clip_sphere = [sin(f * 0.7) * 3.0, cos(f * 1.9) * 3.0, sin(f * 0.1) * 3.0, cos(f * 1.7) + 2.5]
glUniformMatrix4fv(uniform.proj_matrix, 1, GL_FALSE, proj_matrix)
glUniformMatrix4fv(uniform.mv_matrix, 1, GL_FALSE, mv_matrix)
glUniform4fv(uniform.clip_plane, 1, plane)
glUniform4fv(uniform.clip_sphere, 1, clip_sphere)
glEnable(GL_DEPTH_TEST)
glEnable(GL_CLIP_DISTANCE0)
glEnable(GL_CLIP_DISTANCE1)
glActiveTexture(GL_TEXTURE0)
glBindTexture(GL_TEXTURE_2D, tex_dragon)
myobject.render()
glutSwapBuffers()
def reshape(self, width, height):
self.width = width
self.height = height
def keyboard(self, key, x, y ):
global fullscreen
global paused
print ('key:' , key)
if key == b'\x1b': # ESC
sys.exit()
elif key == b'f' or key == b'F': #fullscreen toggle
if (fullscreen == True):
glutReshapeWindow(512, 512)
glutPositionWindow(int((1360/2)-(512/2)), int((768/2)-(512/2)))
fullscreen = False
else:
glutFullScreen()
fullscreen = True
elif key == b'p' or key == b'P':
paused = not paused
elif key == b'r' or key == b'R':
pass
print('done')
def init(self):
pass
def timer(self, blah):
glutPostRedisplay()
glutTimerFunc( int(1/60), self.timer, 0)
time.sleep(1/60.0)
if __name__ == '__main__':
start = time.time()
glutInit()
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH)
glutInitWindowSize(512, 512)
w1 = glutCreateWindow('OpenGL SuperBible - Clip Distance')
glutInitWindowPosition(int((1360/2)-(512/2)), int((768/2)-(512/2)))
fullscreen = False
#glutFullScreen()
scene = Scene(512,512)
glutReshapeFunc(scene.reshape)
glutDisplayFunc(scene.display)
glutKeyboardFunc(scene.keyboard)
glutIdleFunc(scene.display)
#glutTimerFunc( int(1/60), scene.timer, 0)
scene.init()
glutMainLoop()
ported into python from clipdistance.cpp , source of sbmobject.cpp just in case sbmloader.py is in question for the texture issue.

The C++ code from the example
vmath::mat4 plane_matrix = vmath::rotate(f * 6.0f, 1.0f, 0.0f, 0.0f) *
vmath::rotate(f * 7.3f, 0.0f, 1.0f, 0.0f);
corresponds to the following python code
RX = (GLfloat * 16)(*identityMatrix)
m3dRotationMatrix44(RX, f * 6.0, 1.0, 0.0, 0.0)
RY = (GLfloat * 16)(*identityMatrix)
m3dRotationMatrix44(RY, f * 7.3, 0.0, 1.0, 0.0)
plane_matrix = (GLfloat * 16)(*identityMatrix)
plane_matrix = m3dMultiply(RX , RY)
Note, you've to swap RX and RY in the matrix multiplication.
Your functions length and normalize can only deal with vectors which have 3 components (x, y, z). In compare the C++ function vmath::normalize from the example can handle vectors with 4 components (x, y, z, w), too.
Further the "division by zero" handling is missing in normalize.
Adapt the functions normalize and length, to deal with any vector size.
If the length of a vector is 0, then all its components are 0. There is no correct solution for that, so just return a copy of the vector itself.
def length(v):
sum_sq = sum([s*s for s in v])
return math.sqrt(sum_sq)
def normalize(v):
l = length(v)
if l == 0.0:
return v[:]
return [s/l for s in v]
Now you can port the C++ code from the example
vmath::vec4 plane = plane_matrix[0];
plane[3] = 0.0f;
plane = vmath::normalize(plane);
very straight to python:
plane = plane_matrix[0:4]
plane[3] = 0
plane = normalize(plane)
Further, there is an issue in the sbmloader module.
Only the array of vertex coordinates and texture coordinates is specified. The normal vectors are skipped.
Just skip the line
if attrib.name=='position' or attrib.name=='map1':
to fix the issue:
for attrib_i, attrib in enumerate(vertex_attrib_chunk.attrib_data):
#if attrib.name=='position' or attrib.name=='map1':
glVertexAttribPointer(attrib_i,
attrib.size, attrib.type,
GL_TRUE if (attrib.flags & SB6M_VERTEX_ATTRIB_FLAG_NORMALIZED) != 0 else GL_FALSE,
attrib.stride, ctypes.c_void_p(int(attrib.data_offset)))
glEnableVertexAttribArray(attrib_i)
If you additionally want to wrap a texture to the model, then you've to add the texture coordinate attribute to the vertex shader:
layout (location = 2) in vec2 tc;
And to pass it by an output to the next shader stage
out VS_OUT
{
vec3 N;
vec3 L;
vec3 V;
vec2 T;
} vs_out;
void main()
{
// ...
vs_out.T = tc;
// ...
}
In the fragment shader you've to add the texture sampler uniform
layout (binding = 0) uniform sampler2D tex;
Read the color form the texture
vec4 texColor = texture(tex, fs_in.T);
Multiply the output color by the texture color
color = vec4(diffuse + specular + rim, 1.0) * texColor;
Fragment shader (note, I changed diffuse_albedo):
#version 420 core
// Output
layout (location = 0) out vec4 color;
// Input from vertex shader
in VS_OUT
{
vec3 N;
vec3 L;
vec3 V;
vec2 T;
} fs_in;
// Material properties
uniform vec3 diffuse_albedo = vec3(0.5);
uniform vec3 specular_albedo = vec3(0.7);
uniform float specular_power = 128.0;
uniform vec3 rim_color = vec3(0.1, 0.2, 0.2);
uniform float rim_power = 5.0;
layout (binding = 0) uniform sampler2D tex;
vec3 calculate_rim(vec3 N, vec3 V)
{
float f = 1.0 - dot(N, V);
f = smoothstep(0.0, 1.0, f);
f = pow(f, rim_power);
return f * rim_color;
}
void main(void)
{
// Normalize the incoming N, L and V vectors
vec3 N = normalize(fs_in.N);
vec3 L = normalize(fs_in.L);
vec3 V = normalize(fs_in.V);
// Calculate R locally
vec3 R = reflect(-L, N);
// Compute the diffuse and specular components for each fragment
vec3 diffuse = max(dot(N, L), 0.0) * diffuse_albedo;
vec3 specular = pow(max(dot(R, V), 0.0), specular_power) * specular_albedo;
vec3 rim = calculate_rim(N, V);
// read color from the texture
vec4 texColor = texture(tex, fs_in.T);
// Write final color to the framebuffer
color = vec4(diffuse + specular + rim, 1.0) * texColor;
}
I recommend to add shader compile and link error logging:
glCompileShader(result)
if not glGetShaderiv(result, GL_COMPILE_STATUS):
print( 'compile error:' )
print( glGetShaderInfoLog(result) )
glLinkProgram(program)
if not glGetProgramiv(program, GL_LINK_STATUS):
print( 'link error:' )
print( glGetProgramInfoLog(program) )
Read a texture at the initialization of the application
class Scene:
def __init__(self, width, height):
global myobject, tex_dragon
myobject.load("dragon.sbm")
load_shaders()
ktxobj = KTXObject()
tex_dragon = ktxobj.ktx_load("texture_file_name.ktx")
Bind the texture before drawing the model
glActiveTexture(GL_TEXTURE0)
glBindTexture(GL_TEXTURE_2D, tex_dragon)
myobject.render()

Updating Shader Uniform in OpenGL doesn't work

At the moment I am stuck trying to update uniform values of the vertex and fragment shader. Unfortunately as soon as I call glDrawElements I can't access these values anymore. So I am only able to set them at initialization and then never again. It looks a bit like in this thread, but reinstalling PyOpenGl did not work (MODERN OPENGL can't change uniform value beetween glDrawArrays calls). I would be greatful for any help.
def Video_setupGL():
#Set ViewPort
glViewport(0, 0, 640, 480)
####################
vertices2 = [
0.0, 0.5, -0.5,
0.5, -0.5, -0.5,
-0.5, -0.5, -0.5
]
#####################
vertexShaderSource2 = textwrap.dedent("""#version 330
in vec3 position;
uniform mat4 transform;
void main() { gl_Position = transform * vec4(position, 1.0f); }\
""")
vertexShader = glCreateShader(GL_VERTEX_SHADER)
glShaderSource(vertexShader, vertexShaderSource2)
glCompileShader(vertexShader)
#check if compilation was successful
ret = glGetShaderiv(vertexShader, GL_COMPILE_STATUS)
if not ret:
raise Exception("failed to compile vertex shader")
fragmentSource2 = textwrap.dedent("""#version 330
uniform vec4 ourColor;
void main()
{
##gl_FragColor = vec4(1.0f, 1.0f, 1.0f, 1.0f);
gl_FragColor = ourColor;
}\
""")
fragmentShader = glCreateShader(GL_FRAGMENT_SHADER)
glShaderSource(fragmentShader, fragmentSource2)
glCompileShader(fragmentShader)
ret = glGetShaderiv(fragmentShader, GL_COMPILE_STATUS)
if not ret:
raise Exception("failed to compile fragment shader. Code = " + str(ret))
shaderProgram = glCreateProgram()
glAttachShader(shaderProgram, vertexShader)
glAttachShader(shaderProgram, fragmentShader)
glLinkProgram(shaderProgram)
ret = glGetProgramiv(shaderProgram, GL_LINK_STATUS)
if not ret:
raise Exception("failed to link shader program. Code = " + str(ret))
#################################
#1. Init VBO
vertexBuffer = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer)
glBufferData(GL_ARRAY_BUFFER, np.array(vertices, dtype="float32"), GL_STATIC_DRAW)
#1.2 Init EBO
indices = [0, 1, 3, 1, 2, 3]
ebo = glGenBuffers(1)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, np.array(indices, dtype="int32"), GL_STATIC_DRAW)
#################################
#2. Init VAO
vertexArrayObject = glGenVertexArrays(1)
glBindVertexArray(vertexArrayObject)
#################################
position = glGetAttribLocation(shaderProgram, 'position')
glEnableVertexAttribArray(position)
glVertexAttribPointer(position, 3, GL_FLOAT, GL_FALSE, 3*sizeof(c_float), ctypes.c_void_p(0)) # stride is maybe wrongly set
glEnableVertexAttribArray(0)
glBindVertexArray(0)
glDisableVertexAttribArray(position)
glBindBuffer(GL_ARRAY_BUFFER, 0)
########################
state = [shaderProgram, vertexArrayObject, ebo]
return state
def Video_paintGL(state, posMatrix, i, color):
######posMatrix, i and color are changed everytime Video_paintGL ist executed
shaderProgram, vertexArrayObject, myEbo = state
##############
glClearColor(0.2, 0.2, 0.2, 1.0)
glClear(GL_COLOR_BUFFER_BIT)
glLoadIdentity()
glUseProgram(shaderProgram)
################
transformLoc = glGetUniformLocation(shaderProgram, "transform")
if transformLoc == -1:
raise Exception("Transform Uniform could not be found")
print("Error: " + str(glGetError()))
posMatrix = getRotMatrix(np.array([0,0,1], dtype="float32"), np.pi/4 * (i+1)) #get a rotated identiy matrix around the z axis
glUniformMatrix4fv(transformLoc, 1, GL_FALSE, posMatrix) ###this function makes me sick
colorLoc = glGetUniformLocation(shaderProgram, "ourColor")
print(color)
glUniform4f(colorLoc, color[0], color[1], color[2], 1.0) #this as well
glBindVertexArray(vertexArrayObject)
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, myEbo)
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, None)
glBindVertexArray(0)
glUseProgram(0)

Using a (varying) variable to update gl_PointSize has strange behavior in PyOpenGL

I am trying to dynamically set the point size of my vertexes and I am only able to do so if I use a static non-changing value:
#version 450 core
layout(location = 0) in vec4 vPosition;
layout(location = 4) uniform float Size = 50;
void main()
{
gl_Position = vPosition;
gl_PointSize = Size;
}
Result:
However when I try to update them dynamically I see that only one of the vertices sizes change and the others disappear entirely:
#version 450 core
layout(location = 0) in vec4 vPosition;
layout(location = 4) in float Size;
void main()
{
gl_Position = vPosition;
gl_PointSize = Size;
}
Which I then set it's value:
def drawWithoutVBOs(vertices, indices):
...
glEnableVertexAttribArray(4)
glVertexAttribPointer(4, 1, GL_FLOAT, GL_FALSE, 0, 50)
glDrawElementsus(GL_POINTS, indices)
Result:
Could someone please help me spot what I am doing wrong?
Sourcecode for this project
#!/usr/bin/env python2
import time
from OpenGL.GL import *
from OpenGL.GL.shaders import *
import pygame
from pygame.locals import *
import numpy
width = 640
height = 480
vertices = numpy.array([0.0, 0.5, 0.0,
-0.5, -0.5, 0.0,
0.5, -0.5, 0.0], numpy.float32)
indices = numpy.array([0, 1, 2], numpy.ushort)
def init():
vertexShader = compileShader("""
#version 450 core
layout(location = 0) in vec4 vPosition;
layout(location = 4) in float Size;
//layout(location = 4) uniform float Size = 50;
void main()
{
gl_Position = vPosition;
gl_PointSize = Size;
}""", GL_VERTEX_SHADER)
fragmentShader = compileShader("""
#version 450 core
void main()
{
gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}""", GL_FRAGMENT_SHADER)
program = glCreateProgram()
glAttachShader(program, vertexShader)
glAttachShader(program, fragmentShader)
glBindAttribLocation(program, 0, "vPosition")
glBindAttribLocation(program, 4, "Size")
glLinkProgram(program)
glEnable(GL_VERTEX_PROGRAM_POINT_SIZE) #allow the program to specify the point size
glClearColor(0.0, 0.0, 0.0, 1.0)
return program
def drawWithoutVBOs(vertices, indices):
glEnableVertexAttribArray(0)
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, vertices)
glEnableVertexAttribArray(4)
glVertexAttribPointer(4, 1, GL_FLOAT, GL_FALSE, 0, 50)
glDrawElementsub(GL_POINTS, indices)
#glDrawElements(GL_POINTS, indices.size, GL_UNSIGNED_INT, indices)
def main():
pygame.init()
pygame.display.set_mode((width, height), HWSURFACE|OPENGL|DOUBLEBUF)
program = init()
glViewport(0, 0, width, height)
glClear(GL_COLOR_BUFFER_BIT)
glUseProgram(program)
drawWithoutVBOs(vertices, indices)
pygame.display.flip()
time.sleep(3)
if __name__ == '__main__':
main()

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