I'm considering switching to ModernGL over PyOpenGL, and I'm struggling to implement anything right now.
First of all, I would like to try the classic "triangle that changes shape using a time uniform and sine function", but I'm stuck on how to write to the uniform.
Here is what the documentation says about this:
A uniform is a global GLSL variable declared with the “uniform” storage qualifier. These act as
parameters that the user of a shader program can pass to that program.
In ModernGL, Uniforms can be accessed using Program.__getitem__() or Program.__iter__().
# Set a vec4 uniform
uniform['color'] = 1.0, 1.0, 1.0, 1.0
# Optionally we can store references to a member and set the value directly
uniform = program['color']
uniform.value = 1.0, 0.0, 0.0, 0.0
uniform = program['cameraMatrix']
uniform.write(camera_matrix)
This is my code:
import moderngl as mgl
import glfw
import numpy as np
import time
from math import sin
glfw.init()
glfw.window_hint(glfw.CONTEXT_VERSION_MAJOR, 3)
glfw.window_hint(glfw.CONTEXT_VERSION_MINOR, 3)
glfw.window_hint(glfw.OPENGL_PROFILE, glfw.OPENGL_CORE_PROFILE)
window = glfw.create_window(800, 600, "__DELETEME__", None, None)
glfw.make_context_current(window)
context = mgl.create_context()
vertex_source = """
#version 330 core
in vec2 aPos;
uniform float time;
void main() {
gl_Position = vec4(aPos.x, aPos.y + sin(time), 0.0, 1.0);
}
"""
fragment_source = """
#version 330 core
out vec4 color;
void main(){
color = vec4(0.0, 0.0, 1.0, 1.0);
}
"""
program = context.program(vertex_shader=vertex_source, fragment_shader=fragment_source)
data = np.array([
0.5, 0,
-0.5, 0,
0, 0.5], dtype = "float32")
vbo = context.buffer(data.tobytes())
vao = context.vertex_array(program, vbo, "aPos")
uniform = program["time"]
uniform.value = 1.0
while not glfw.window_should_close(window):
now = time.time()
vao.render()
elapsed = time.time() - now
glfw.poll_events()
glfw.swap_buffers(window)
glfw.terminate()
Now it draws nothing. What am I doing wrong? Thanks!
The elapsed time is the difference between the start time and the current time. Get the start time before the application loop and compute the elapsed time in the loop in every frame:
start_time = time.time()
while not glfw.window_should_close(window):
elapsed = time.time() - start_time
# [...]
The value of the uniform "time" has to be updated continuously in the loop:
while not glfw.window_should_close(window):
# [...]
uniform.value = elapsed
You have to clear the display in every frame, in the application loop (See ModernGL Context):
while not glfw.window_should_close(window):
# [...]
context.clear(0.0, 0.0, 0.0)
vao.render()
Complete example:
import moderngl as mgl
import glfw
import numpy as np
import time
from math import sin
glfw.init()
glfw.window_hint(glfw.CONTEXT_VERSION_MAJOR, 3)
glfw.window_hint(glfw.CONTEXT_VERSION_MINOR, 3)
glfw.window_hint(glfw.OPENGL_PROFILE, glfw.OPENGL_CORE_PROFILE)
window = glfw.create_window(800, 600, "__DELETEME__", None, None)
glfw.make_context_current(window)
context = mgl.create_context()
vertex_source = """
#version 330 core
in vec2 aPos;
uniform float time;
void main() {
gl_Position = vec4(aPos.x, aPos.y + sin(time), 0.0, 1.0);
}
"""
fragment_source = """
#version 330 core
out vec4 color;
void main(){
color = vec4(0.0, 0.0, 1.0, 1.0);
}
"""
program = context.program(vertex_shader=vertex_source, fragment_shader=fragment_source)
data = np.array([
0.5, 0,
-0.5, 0,
0, 0.5], dtype = "float32")
vbo = context.buffer(data.tobytes())
vao = context.vertex_array(program, vbo, "aPos")
uniform = program["time"]
uniform.value = 1.0
start_time = time.time()
while not glfw.window_should_close(window):
elapsed = time.time() - start_time
uniform.value = elapsed
context.clear(0.0, 0.0, 0.0)
vao.render()
glfw.poll_events()
glfw.swap_buffers(window)
glfw.terminate()
Related
I have written a code to render a triangle using a shader program. I want to rotate the triangle. I'm using PyGLM to set a transformation matrix. Here I'm presenting the whole code. If I run this code a triangle is appearing in the window as expected, but there is no rotation. I think I've failed to pass the transformation matrix to the buffer.
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *
from OpenGL.GL import shaders
import numpy as np
import glm
VERTEX_SHADER = """
#version 330
in vec4 position;
in vec3 color;
out vec3 newColor;
void main()
{
gl_Position = position;
newColor = color;
}
"""
FRAGMENT_SHADER = """
#version 330
in vec3 newColor;
out vec4 outColor;
void main()
{
outColor = vec4(newColor,1.0f);
}
"""
shaderProgram = None
def initliaze():
global VERTEXT_SHADER
global FRAGMEN_SHADER
global shaderProgram
vertexshader = shaders.compileShader(VERTEX_SHADER, GL_VERTEX_SHADER)
fragmentshader = shaders.compileShader(FRAGMENT_SHADER, GL_FRAGMENT_SHADER)
shaderProgram = shaders.compileProgram(vertexshader, fragmentshader)
triangles = [-0.5, -0.5, 0.0, 1.0,0.0,0.0,
0.5, -0.5, 0.0, 0.0,1.0,0.0,
0.0, 0.5, 0.0, 0,0,0.0,1.0]
triangles = np.array(triangles, dtype=np.float32)
VBO = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, VBO)
glBufferData(GL_ARRAY_BUFFER, triangles.nbytes, triangles, GL_DYNAMIC_DRAW)
position = glGetAttribLocation(shaderProgram, 'position')
glVertexAttribPointer(position, 3, GL_FLOAT, GL_FALSE, 24, ctypes.c_void_p(0))
glEnableVertexAttribArray(position)
color = glGetAttribLocation(shaderProgram, 'color')
glVertexAttribPointer(color, 3, GL_FLOAT, GL_FALSE, 24, ctypes.c_void_p(12))
glEnableVertexAttribArray(color)
def render():
global shaderProgram
global angle
#shader
glUseProgram(shaderProgram)
glClearColor(0, 0, 0, 1)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
#transform matrix
transform = glm.mat4(1)
transform = glm.translate(transform, glm.vec3(0.5,-0.5,0.0))
transform = glm.rotate(transform, glutGet(GLUT_ELAPSED_TIME),glm.vec3(0,0,1))
transformLoc = glGetUniformLocation(shaderProgram,"transform")
glUniformMatrix4fv(transformLoc, 1, GL_FALSE, glm.value_ptr(transform))
#render program
glDrawArrays(GL_TRIANGLES, 0, 3)
glUseProgram(0)
glutSwapBuffers()
def main():
glutInit([])
glutInitWindowSize(640, 480)
glutCreateWindow("pyopengl with glut 2")
initliaze()
glutDisplayFunc(render)
glutMainLoop()
if __name__ == '__main__':
main()
In VERTEX_SHADER you didn't mentioned transform variable. So your triangle position remain fixed after you run the program. Change your VERTEX_SHADER as following.
VERTEX_SHADER = """
#version 330
in vec4 position;
in vec3 color;
out vec3 newColor;
uniform mat4 transform;
void main()
{
gl_Position = transform*position;
newColor = color;
}
"""
In your code you are accessing the location of location of a uniform variable transform by following line.
transformLoc = glGetUniformLocation(shaderProgram,"transform")
You should add glutPostRedisplay() function after the glutSwapBuffers() function to visualize the continuous change.
Looks like you will want to create your own library from GLM. What you're doing in the code above no longer works. As another user stated, this is a good template to build functionality from. I'd suggest downloading GLM, taking it apart, and reverse engineering what you need into Python.
I am using the following code to render a rectangle on screen, using moderngl and moderngl_window. This is mostly derived from their examples:
import moderngl
import moderngl_window as mglw
import glfw
import numpy as np
import OpenGL.GL
import OpenGL.GLUT
import OpenGL.GLU
class MyWin(mglw.WindowConfig):
gl_version = (3, 3)
title = "Hello World"
window_size = (1280, 720)
aspect_ratio = 16/9;
resizable = True
samples = 4
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.prog = self.ctx.program(
vertex_shader='''
#version 330
in vec2 vert;
void main() {
gl_Position = vec4(vert.x, vert.y*1.7777, 0.0, 1.0);
}
''',
fragment_shader='''
#version 330
out vec4 color;
void main() {
color = vec4(0.3, 0.5, 1.0, 1.0);
}
''',
)
self.vertices = np.array([
-0.8, 0.8,
-0.8, -0.8,
0.8, -0.8,
0.8, 0.8,
-0.8, 0.8,
0.8,-0.8
])
self.vbo = self.ctx.buffer(self.vertices.astype('f4').tobytes())
# self.texCoordBuffer = self.ctx.buffer(texCoord.astype('f4').tobytes());
self.vao = self.ctx.simple_vertex_array(self.prog, self.vbo, 'vert');
# self.vao.bind(1,'f',self.texCoordBuffer,'2f');
# self.time = self.prog['time'];
#classmethod
def setVertices(self, vertices):
print("vertices have been set")
self.vertices = vertices
#classmethod
def run(cls):
mglw.run_window_config(cls);
def render(self, time, frame_time):
# self.time.value = time
self.ctx.clear(0.0, 0.0, 0.0)
self.vao.render()
but I can't figure out what function I need to call with moderngl to set the rendering mode to GL_LINES instead of GL_TRIANGLES
I think I need to call glDrawArraysbut I can't find how to access it with moderngl.
Thanks for your help!
You can choose the Primitive type by setting the mode argument when you invoke moderngl.VertexArray.render(). The default argument is TRIANGLES. Set the mode LINES for the primitive type GL_LINES:
self.vao.render()
self.vao.render(moderngl.LINES)
I am trying to render an obj (a human body model) to its corresponding silhouette image given camera intrinsic&&extrinsic parameters and I want to know which renderer is suitable for the task. I don't want real time display of the rendered images because efficiency is my top concern. I have 100000 3d objects and i need to write a script to render the silhouette images of those objects in one go.
Here is a small example rendering with OpenGL to an image using ModernGL and Pillow
pillow docs
ModernGL docs
Sample code:
import struct
import ModernGL
from PIL import Image
ctx = ModernGL.create_standalone_context()
prog = ctx.program([
ctx.vertex_shader('''
#version 330
in vec2 vert;
void main() {
gl_Position = vec4(vert, 0.0, 1.0);
}
'''),
ctx.fragment_shader('''
#version 330
out vec4 color;
void main() {
color = vec4(0.3, 0.5, 1.0, 1.0);
}
'''),
])
vbo = ctx.buffer(struct.pack('6f', 0.0, 0.8, -0.6, -0.8, 0.6, -0.8))
vao = ctx.simple_vertex_array(prog, vbo, ['vert'])
fbo = ctx.framebuffer(ctx.renderbuffer((512, 512)))
fbo.use()
ctx.viewport = (0, 0, 512, 512)
ctx.clear(0.9, 0.9, 0.9)
vao.render()
pixels = fbo.read(components=3, alignment=1)
img = Image.frombytes('RGB', fbo.size, pixels).transpose(Image.FLIP_TOP_BOTTOM)
img.show()
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I am looking for a simple modern OpenGL (3.2+)example in Python.
I tried with GLUT and freeGLUT, but I am not able to get a 3.2 context on OS X (Mavericks). (This seems to be a known issue with GLUT/freeGLUT).
GLFW seems to be a modern lightweight alternative to GLUT, but it doesn't seem to have an official Python binding, and I could not find a simple example that uses 3.2 core profile features of OpenGL with GLFW and Python.
(I struggled with this problem, and so it could be useful for others, I am answering below as per SO guidelines.)
The code below uses PyOpenGL, PIL (for textures), numpy, GLFW and the corresponding Python binding cyglfw3.
Here is a screenshot of the output:
The main code is appended below. It uses some utility methods from a file called glutils.py (for loading texture, compiling shaders, etc.) which you can find here:
https://github.com/electronut/pp/tree/master/simplegl
Code listing follows:
import OpenGL
from OpenGL.GL import *
from OpenGL.GLUT import *
import numpy, math, sys, os
import glutils
import cyglfw3 as glfw
strVS = """
#version 330 core
layout(location = 0) in vec3 aVert;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
uniform vec4 uColor;
uniform float uTheta;
out vec4 vCol;
out vec2 vTexCoord;
void main() {
// rotational transform
mat4 rot = mat4(
vec4( cos(uTheta), sin(uTheta), 0.0, 0.0),
vec4(-sin(uTheta), cos(uTheta), 0.0, 0.0),
vec4(0.0, 0.0, 1.0, 0.0),
vec4(0.0, 0.0, 0.0, 1.0)
);
// transform vertex
gl_Position = uPMatrix * uMVMatrix * rot * vec4(aVert, 1.0);
// set color
vCol = vec4(uColor.rgb, 1.0);
// set texture coord
vTexCoord = aVert.xy + vec2(0.5, 0.5);
}
"""
strFS = """
#version 330 core
in vec4 vCol;
in vec2 vTexCoord;
uniform sampler2D tex2D;
uniform bool showCircle;
out vec4 fragColor;
void main() {
if (showCircle) {
// discard fragment outside circle
if (distance(vTexCoord, vec2(0.5, 0.5)) > 0.5) {
discard;
}
else {
fragColor = texture(tex2D, vTexCoord);
}
}
else {
fragColor = texture(tex2D, vTexCoord);
}
}
"""
class Scene:
""" OpenGL 3D scene class"""
# initialization
def __init__(self):
# create shader
self.program = glutils.loadShaders(strVS, strFS)
glUseProgram(self.program)
self.pMatrixUniform = glGetUniformLocation(self.program,
'uPMatrix')
self.mvMatrixUniform = glGetUniformLocation(self.program,
"uMVMatrix")
self.colorU = glGetUniformLocation(self.program, "uColor")
# color
self.col0 = [1.0, 0.0, 0.0, 1.0]
# texture
self.tex2D = glGetUniformLocation(self.program, "tex2D")
# define quad vertices
quadV = [
-0.5, -0.5, 0.0,
0.5, -0.5, 0.0,
-0.5, 0.5, 0.0,
0.5, 0.5, 0.0
]
# set up vertex array object (VAO)
self.vao = glGenVertexArrays(1)
glBindVertexArray(self.vao)
# vertices
self.vertexBuffer = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, self.vertexBuffer)
vertexData = numpy.array(quadV, numpy.float32)
glBufferData(GL_ARRAY_BUFFER, 4*len(vertexData), vertexData,
GL_STATIC_DRAW)
# enable vertex array
glEnableVertexAttribArray(0)
# set buffer data
glBindBuffer(GL_ARRAY_BUFFER, self.vertexBuffer)
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, None)
# unbind VAO
glBindVertexArray(0)
# time
self.t = 0
# texture
self.texId = glutils.loadTexture('test.png')
# show circle?
self.showCircle = False
# step
def step(self):
# increment angle
self.t = (self.t + 1) % 360
# set shader angle in radians
glUniform1f(glGetUniformLocation(self.program, 'uTheta'),
math.radians(self.t))
# render
def render(self, pMatrix, mvMatrix):
# use shader
glUseProgram(self.program)
# set proj matrix
glUniformMatrix4fv(self.pMatrixUniform, 1, GL_FALSE, pMatrix)
# set modelview matrix
glUniformMatrix4fv(self.mvMatrixUniform, 1, GL_FALSE, mvMatrix)
# show circle?
glUniform1i(glGetUniformLocation(self.program, 'showCircle'),
self.showCircle)
# enable texture
glActiveTexture(GL_TEXTURE0)
glBindTexture(GL_TEXTURE_2D, self.texId)
glUniform1i(self.tex2D, 0)
# bind VAO
glBindVertexArray(self.vao)
# draw
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4)
# unbind VAO
glBindVertexArray(0)
class RenderWindow:
"""GLFW Rendering window class"""
def __init__(self):
# save current working directory
cwd = os.getcwd()
# initialize glfw - this changes cwd
glfw.Init()
# restore cwd
os.chdir(cwd)
# version hints
glfw.WindowHint(glfw.CONTEXT_VERSION_MAJOR, 3)
glfw.WindowHint(glfw.CONTEXT_VERSION_MINOR, 3)
glfw.WindowHint(glfw.OPENGL_FORWARD_COMPAT, GL_TRUE)
glfw.WindowHint(glfw.OPENGL_PROFILE, glfw.OPENGL_CORE_PROFILE)
# make a window
self.width, self.height = 640, 480
self.aspect = self.width/float(self.height)
self.win = glfw.CreateWindow(self.width, self.height, "test")
# make context current
glfw.MakeContextCurrent(self.win)
# initialize GL
glViewport(0, 0, self.width, self.height)
glEnable(GL_DEPTH_TEST)
glClearColor(0.5, 0.5, 0.5,1.0)
# set window callbacks
glfw.SetMouseButtonCallback(self.win, self.onMouseButton)
glfw.SetKeyCallback(self.win, self.onKeyboard)
glfw.SetWindowSizeCallback(self.win, self.onSize)
# create 3D
self.scene = Scene()
# exit flag
self.exitNow = False
def onMouseButton(self, win, button, action, mods):
#print 'mouse button: ', win, button, action, mods
pass
def onKeyboard(self, win, key, scancode, action, mods):
#print 'keyboard: ', win, key, scancode, action, mods
if action == glfw.PRESS:
# ESC to quit
if key == glfw.KEY_ESCAPE:
self.exitNow = True
else:
# toggle cut
self.scene.showCircle = not self.scene.showCircle
def onSize(self, win, width, height):
#print 'onsize: ', win, width, height
self.width = width
self.height = height
self.aspect = width/float(height)
glViewport(0, 0, self.width, self.height)
def run(self):
# initializer timer
glfw.SetTime(0.0)
t = 0.0
while not glfw.WindowShouldClose(self.win) and not self.exitNow:
# update every x seconds
currT = glfw.GetTime()
if currT - t > 0.1:
# update time
t = currT
# clear
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
# build projection matrix
pMatrix = glutils.perspective(45.0, self.aspect, 0.1, 100.0)
mvMatrix = glutils.lookAt([0.0, 0.0, -2.0], [0.0, 0.0, 0.0],
[0.0, 1.0, 0.0])
# render
self.scene.render(pMatrix, mvMatrix)
# step
self.scene.step()
glfw.SwapBuffers(self.win)
# Poll for and process events
glfw.PollEvents()
# end
glfw.Terminate()
# main() function
def main():
print 'starting simpleglfw...'
rw = RenderWindow()
rw.run()
# call main
if __name__ == '__main__':
main()
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I am having trouble passing projection and modelview matrices into the GLSL shader from my PyOpenGL code. My understanding is that OpenGL matrices are column major, but when I pass in projection and modelview matrices as shown, I don't see anything. I tried the transpose of the matrices, and it worked for the modelview matrix, but the projection matrix doesn't work either way. Here is the code:
import OpenGL
from OpenGL.GL import *
from OpenGL.GL.shaders import *
from OpenGL.GLU import *
from OpenGL.GLUT import *
from OpenGL.GLUT.freeglut import *
from OpenGL.arrays import vbo
import numpy, math, sys
strVS = """
attribute vec3 aVert;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
uniform vec4 uColor;
varying vec4 vCol;
void main() {
// option #1 - fails
gl_Position = uPMatrix * uMVMatrix * vec4(aVert, 1.0);
// option #2 - works
gl_Position = vec4(aVert, 1.0);
// set color
vCol = vec4(uColor.rgb, 1.0);
}
"""
strFS = """
varying vec4 vCol;
void main() {
// use vertex color
gl_FragColor = vCol;
}
"""
# 3D scene
class Scene:
# initialization
def __init__(self):
# create shader
self.program = compileProgram(compileShader(strVS,
GL_VERTEX_SHADER),
compileShader(strFS,
GL_FRAGMENT_SHADER))
glUseProgram(self.program)
self.pMatrixUniform = glGetUniformLocation(self.program, 'uPMatrix')
self.mvMatrixUniform = glGetUniformLocation(self.program,
"uMVMatrix")
self.colorU = glGetUniformLocation(self.program, "uColor")
# attributes
self.vertIndex = glGetAttribLocation(self.program, "aVert")
# color
self.col0 = [1.0, 1.0, 0.0, 1.0]
# define quad vertices
s = 0.2
quadV = [
-s, s, 0.0,
-s, -s, 0.0,
s, s, 0.0,
s, s, 0.0,
-s, -s, 0.0,
s, -s, 0.0
]
# vertices
self.vertexBuffer = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, self.vertexBuffer)
vertexData = numpy.array(quadV, numpy.float32)
glBufferData(GL_ARRAY_BUFFER, 4*len(vertexData), vertexData,
GL_STATIC_DRAW)
# render
def render(self, pMatrix, mvMatrix):
# use shader
glUseProgram(self.program)
# set proj matrix
glUniformMatrix4fv(self.pMatrixUniform, 1, GL_FALSE, pMatrix)
# set modelview matrix
glUniformMatrix4fv(self.mvMatrixUniform, 1, GL_FALSE, mvMatrix)
# set color
glUniform4fv(self.colorU, 1, self.col0)
#enable arrays
glEnableVertexAttribArray(self.vertIndex)
# set buffers
glBindBuffer(GL_ARRAY_BUFFER, self.vertexBuffer)
glVertexAttribPointer(self.vertIndex, 3, GL_FLOAT, GL_FALSE, 0, None)
# draw
glDrawArrays(GL_TRIANGLES, 0, 6)
# disable arrays
glDisableVertexAttribArray(self.vertIndex)
class Renderer:
def __init__(self):
pass
def reshape(self, width, height):
self.width = width
self.height = height
self.aspect = width/float(height)
glViewport(0, 0, self.width, self.height)
glEnable(GL_DEPTH_TEST)
glDisable(GL_CULL_FACE)
glClearColor(0.8, 0.8, 0.8,1.0)
glutPostRedisplay()
def keyPressed(self, *args):
sys.exit()
def draw(self):
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
# build projection matrix
fov = math.radians(45.0)
f = 1.0/math.tan(fov/2.0)
zN, zF = (0.1, 100.0)
a = self.aspect
pMatrix = numpy.array([f/a, 0.0, 0.0, 0.0,
0.0, f, 0.0, 0.0,
0.0, 0.0, (zF+zN)/(zN-zF), -1.0,
0.0, 0.0, 2.0*zF*zN/(zN-zF), 0.0], numpy.float32)
# modelview matrix
mvMatrix = numpy.array([1.0, 0.0, 0.0, 0.0,
0.0, 1.0, 0.0, 0.0,
0.0, 0.0, 1.0, 0.0,
0.5, 0.0, -5.0, 1.0], numpy.float32)
# render
self.scene.render(pMatrix, mvMatrix)
# swap buffers
glutSwapBuffers()
def run(self):
glutInitDisplayMode(GLUT_RGBA)
glutInitWindowSize(400, 400)
self.window = glutCreateWindow("Minimal")
glutReshapeFunc(self.reshape)
glutDisplayFunc(self.draw)
glutKeyboardFunc(self.keyPressed) # Checks for key strokes
self.scene = Scene()
glutMainLoop()
glutInit(sys.argv)
prog = Renderer()
prog.run()
When I use option #2 in the shader without either matrix, I get the following output:
What am I doing wrong?