Texture Buffers in GL3

Texture Buffers in GL3

A new addition in the GL3 engine is a feature called texture-buffers. Texture-buffers use the new jit.gl.buffer object in conjunction with jit.gl.mesh and allow you to access any of the buffers of a jit.gl.mesh (position, normal, vertex_attr, etc.) as a 1D texture in any of the mesh's shader programs, using the texelFetch command.

You can declare a mesh's buffer as a texture-buffer via the new jit.gl.buffer using the attribute texbuf 1 and must specify the name of the buffer to bind as a texture (position, normal, vertex_attr, etc.) using the attribute type. It is important to note that any normal textures will be bound first, and then texture-buffers. Texture-buffers are declared in the shader as samplerBuffer uniforms.

So if you have two texture-buffers patched into a jit.gl.mesh that look like this:

[ jit.gl.buffer @type vertex_attr0 @texbuf 1 ]
      [ jit.gl.buffer @type vertex_attr1 @texbuf 1 ]
then in your shader params declaration you need something like:
<param name="tex1" type="int" default="0" />
      <param name="tex2" type="int" default="1" />
      <param name="texbuf1" type="int" default="2" />
      <param name="texbuf2" type="int" default="3" />
and in the program body:
uniform sampler2DRect tex1;
      uniform sampler2DRect tex2;
      uniform samplerBuffer texbuf1;
      uniform samplerBuffer texbuf2;
This allows you access to the sampled texture for use in the rest of the shader. To sample, use texelFetch:
vec3 bufval = texelFetch(texbuf1, index).xyz;
where index is an integer between 0 and the buffer width minus one.

For an example, check out the tb.point.lights patch in the gl3 examples.

See Also

Name Description
GL3 Package Topics GL3 Package Topics
jit.gl.buffer
jit.gl.mesh Generate GL geometry from matrices
jit.gl.tf