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from __future__ import print_function
import os
if not os.environ.get( 'PYOPENGL_PLATFORM' ):
os.environ['PYOPENGL_PLATFORM'] = 'osmesa'
import OpenGL
OpenGL.USE_ACCELERATE = False
from OpenGL.GL import *
from OpenGL.arrays import vbo
from OpenGL import extensions
from OpenGL.GL.ARB.fragment_program import glGenProgramsARB
from OpenGL.GLU import *
from OpenGL.osmesa import *
from OpenGL.GL import shaders
from numpy import arange, array
import contextlib
def write_ppm(buf, filename):
"""Write traditional ASCII PPM file from buffer"""
with open(filename, "w") as f:
h, w, c = buf.shape
print( "P3", file=f)
print( "# ascii ppm file created by osmesa",file=f)
print( "%i %i" % (w, h),file=f)
print("255",file=f)
for y in range(h - 1, -1, -1):
for x in range(w):
pixel = buf[y, x]
l = " %3d %3d %3d" % (pixel[0], pixel[1], pixel[2])
f.write(l)
f.write("\n")
@contextlib.contextmanager
def osmesa_context(width=400, height=400, output='output.ppm'):
"""Do OSMesa rendering context setup and write to output if non-null"""
from OpenGL import arrays
ctx = OSMesaCreateContext(OSMESA_RGBA, None)
buf = arrays.GLubyteArray.zeros((height, width, 4))
assert(OSMesaMakeCurrent(ctx, buf, GL_UNSIGNED_BYTE, width, height))
assert(OSMesaGetCurrentContext())
yield (ctx, buf)
if output:
write_ppm(buf,output)
OSMesaDestroyContext(ctx)
def setup():
"""Setup the rendering passes
Taken from `OpenGLContext/tests/shader_4.py`
"""
vertex = shaders.compileShader(
"""
uniform float tween;
attribute vec3 position;
attribute vec3 tweened;
attribute vec3 color;
varying vec4 baseColor;
void main() {
gl_Position = gl_ModelViewProjectionMatrix * mix(
vec4( position,1.0),
vec4( tweened,1.0),
tween
);
baseColor = vec4(color,1.0);
}""",
GL_VERTEX_SHADER
)
fragment = shaders.compileShader(
"""
varying vec4 baseColor;
void main() {
gl_FragColor = baseColor;
}""",
GL_FRAGMENT_SHADER
)
shader = shaders.compileProgram(vertex,fragment)
vertices = vbo.VBO(
array( [
[ 0, 1, 0, 1,3,0, 0,1,0 ],
[ -1,-1, 0, -1,-1,0, 1,1,0 ],
[ 1,-1, 0, 1,-1,0, 0,1,1 ],
[ 2,-1, 0, 2,-1,0, 1,0,0 ],
[ 4,-1, 0, 4,-1,0, 0,1,0 ],
[ 4, 1, 0, 4,9,0, 0,0,1 ],
[ 2,-1, 0, 2,-1,0, 1,0,0 ],
[ 4, 1, 0, 1,3,0, 0,0,1 ],
[ 2, 1, 0, 1,-1,0, 0,1,1 ],
],'f')
)
position_location = glGetAttribLocation(
shader, 'position'
)
tweened_location = glGetAttribLocation(
shader, 'tweened',
)
color_location = glGetAttribLocation(
shader, 'color'
)
tween_location = glGetUniformLocation(
shader, 'tween',
)
return {
'shader': shader,
'position_location': position_location,
'tweened_location': tweened_location,
'color_location': color_location,
'tween_location': tween_location,
'vertices': vertices,
}
def render(names, fraction=.5):
glUseProgram(names['shader'])
glUniform1f(names['tween_location'], fraction)
with names['vertices']:
try:
glEnableVertexAttribArray( names['position_location'] )
glEnableVertexAttribArray( names['tweened_location'] )
glEnableVertexAttribArray( names['color_location'] )
stride = 9*4
glVertexAttribPointer(
names['position_location'],
3, GL_FLOAT,False, stride, names['vertices']
)
glVertexAttribPointer(
names['tweened_location'],
3, GL_FLOAT,False, stride, names['vertices']+12
)
glVertexAttribPointer(
names['color_location'],
3, GL_FLOAT,False, stride, names['vertices']+24
)
glDrawArrays(GL_TRIANGLES, 0, 9)
finally:
glDisableVertexAttribArray( names['position_location'] )
glDisableVertexAttribArray( names['tweened_location'] )
glDisableVertexAttribArray( names['color_location'] )
def main():
with osmesa_context(400,400) as context:
print('Queried extensions:', sorted(extensions.GLQuerier.pullExtensions()))
print('Queried version:', extensions.GLQuerier.pullVersion())
names = setup()
for fraction in arange(0,.5,.1):
glClearColor(0.0,0.0,1.0,1.0)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT )
print("Rendering: %s"%(fraction,))
render(names,fraction)
glFinish()
if __name__ == '__main__':
main()
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