Created
December 9, 2012 04:33
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A short example of how to use vertex array objects in PyOpenGL
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import OpenGL.GL as GL | |
import OpenGL.GL.shaders | |
import ctypes | |
import pygame | |
import numpy | |
vertex_shader = """ | |
#version 330 | |
in vec4 position; | |
void main() | |
{ | |
gl_Position = position; | |
} | |
""" | |
fragment_shader = """ | |
#version 330 | |
void main() | |
{ | |
gl_FragColor = vec4(1.0f, 1.0f, 1.0f, 1.0f); | |
} | |
""" | |
vertices = [ 0.6, 0.6, 0.0, 1.0, | |
-0.6, 0.6, 0.0, 1.0, | |
0.0, -0.6, 0.0, 1.0] | |
vertices = numpy.array(vertices, dtype=numpy.float32) | |
def create_object(shader): | |
# Create a new VAO (Vertex Array Object) and bind it | |
vertex_array_object = GL.glGenVertexArrays(1) | |
GL.glBindVertexArray( vertex_array_object ) | |
# Generate buffers to hold our vertices | |
vertex_buffer = GL.glGenBuffers(1) | |
GL.glBindBuffer(GL.GL_ARRAY_BUFFER, vertex_buffer) | |
# Get the position of the 'position' in parameter of our shader and bind it. | |
position = GL.glGetAttribLocation(shader, 'position') | |
GL.glEnableVertexAttribArray(position) | |
# Describe the position data layout in the buffer | |
GL.glVertexAttribPointer(position, 4, GL.GL_FLOAT, False, 0, ctypes.c_void_p(0)) | |
# Send the data over to the buffer | |
GL.glBufferData(GL.GL_ARRAY_BUFFER, 48, vertices, GL.GL_STATIC_DRAW) | |
# Unbind the VAO first (Important) | |
GL.glBindVertexArray( 0 ) | |
# Unbind other stuff | |
GL.glDisableVertexAttribArray(position) | |
GL.glBindBuffer(GL.GL_ARRAY_BUFFER, 0) | |
return vertex_array_object | |
def display(shader, vertex_array_object): | |
GL.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT) | |
GL.glUseProgram(shader) | |
GL.glBindVertexArray( vertex_array_object ) | |
GL.glDrawArrays(GL.GL_TRIANGLES, 0, 3) | |
GL.glBindVertexArray( 0 ) | |
GL.glUseProgram(0) | |
def main(): | |
pygame.init() | |
screen = pygame.display.set_mode((512, 512), pygame.OPENGL|pygame.DOUBLEBUF) | |
GL.glClearColor(0.5, 0.5, 0.5, 1.0) | |
GL.glEnable(GL.GL_DEPTH_TEST) | |
shader = OpenGL.GL.shaders.compileProgram( | |
OpenGL.GL.shaders.compileShader(vertex_shader, GL.GL_VERTEX_SHADER), | |
OpenGL.GL.shaders.compileShader(fragment_shader, GL.GL_FRAGMENT_SHADER) | |
) | |
vertex_array_object = create_object(shader) | |
clock = pygame.time.Clock() | |
while True: | |
for event in pygame.event.get(): | |
if event.type == pygame.QUIT: | |
return | |
if event.type == pygame.KEYUP and event.key == pygame.K_ESCAPE: | |
return | |
display(shader, vertex_array_object) | |
pygame.display.flip() | |
if __name__ == '__main__': | |
try: | |
main() | |
finally: | |
pygame.quit() |
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