Re: [PyOpenGL-Users] Help with VAOs

[rndblnch <rnd...@gm...>]

Johannes Bauer <dfnsonfsduifb <at> gmx.de> writes:

> 
> Hello list,
> 
> I'm trying to store objects (currently only vertices) on the graphics
> card so that I can avoid lots of:
> 
> glBegin()
> glVertex(...)
> [...]
> glEnd()

you may find this tutorial useful:
https://bitbucket.org/rndblnch/opengl-programmable/src

it shows the transformation of a minimal sample from direct mode to the
"modern" programmable pipeline step by step.
you can easily diff two successive versions of the code, e.g.:

diff 01-direct.py 03-array.py 
5c5
< 01-direct.py
---
> 03-array.py
7c7
< OpenGL 1.0 rendering using per vertex primitive
---
> OpenGL 1.1 rendering using arrays
71a72,75
> def flatten(*lll):
> 	return [u for ll in lll for l in ll for u in l]
> 
> 
72a77,83
> 	# enabling arrays
> 	glEnableClientState(GL_VERTEX_ARRAY)
> 	glEnableClientState(GL_TEXTURE_COORD_ARRAY)
> 	glEnableClientState(GL_NORMAL_ARRAY)
> 	glEnableClientState(GL_COLOR_ARRAY)
> 	
> 	# model data
76,79c87,90
< 	verticies, tex_coords, normals, colors = (model.verticies,
< 	                                          model.tex_coords,
< 	                                          model.normals,
< 	                                          model.colors)
---
> 	verticies  = flatten(model.verticies)
> 	tex_coords = flatten(model.tex_coords)
> 	normals    = flatten(model.normals)
> 	colors     = flatten(model.colors)
82a94,98
> 	glVertexPointer(3, GL_FLOAT, 0, verticies)
> 	glTexCoordPointer(3, GL_FLOAT, 0, tex_coords)
> 	glNormalPointer(GL_FLOAT, 0, normals)
> 	glColorPointer(3, GL_FLOAT, 0, colors)
> 	
90,97c106,108
< 		glBegin(GL_TRIANGLE_STRIP)
< 		for i in range(offset, offset+size):
< 			index = indicies[i]
< 			glColor3f(*colors[index])
< 			glNormal3f(*normals[index])
< 			glTexCoord3f(*tex_coords[index])
< 			glVertex3f(*verticies[index])
< 		glEnd()
---
> 		glDrawElements(GL_TRIANGLE_STRIP,
> 		               size, GL_UNSIGNED_INT,
> 		               indicies[offset:offset+size])

renaud