Looking for a simple OpenGL (3.2+) Python example that uses GLFW

Question

I am looking for a simple modern OpenGL example (3.2+) in Python.

I tried with GLUT and freeGLUT, but I cannot get context 3.2 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 bundle, and I could not find a simple example that uses 3.2 basic OpenGL profile functions with GLFW and Python.

(I struggled with this problem, and therefore it may be useful for others, I will answer below in accordance with the recommendations of SO. ).

Answer 1

The code below uses PyOpenGL , PIL (for textures), numpy , GLFW and the corresponding Python bundle cyglfw3 .

Here is a screenshot of the output:

The main code is added below. It uses some utilities from a file called glutils.py (for loading textures, compiling shaders, etc.), which you can find here:

https://github.com/electronut/pp/tree/master/simplegl

The following is a list of codes:

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()