View Full Version : vs texelFetch

06-26-2012, 03:09 PM

I'm having trouble making sense of an issue I have.
I'm trying to store vertex positions in a texture and pass indices to the shader in the vbo.

Now texelFetch returns complete garbage, although the texture seems to be okay (here's what apitrace is showing (http://www.sw-ores.de/problem/apitrace_drawstate.png))

this is how i try to get the position from the texture in the vertex shader:

void main()
indOut.m = indIn[0];
indOut.n1 = indIn[1];
indOut.n2 = indIn[2];

indOut.debugVert = vec4(floor(indOut.m%11)*1.0f/11, 1.0f-floor(indOut.m%11)*1.0f/11, 0.0f, 1.0f);

ivec2 indices = ivec2(floor(indOut.m % 11), floor(indOut.m / 11));
vec4 position = texelFetch(hvt, indices, 0);

indOut.debugVert += position*0.01f;
if(position.length() == 4.0f)
indOut.debugVert += vec4(0.0,0.0,1.0,0.0);

gl_Position = position;
the debugVert is just a color I use to identify issues in the Vertex Shader and to ensure that the texture changes the color (else it gets optimized out). Only the m component of indOut is used, although three indices are passed per vertex. strangely the if statement is always true.

Here's what's inside the texture (http://www.sw-ores.de/problem/apitrace_texturedata.png)

I have no Idea what I'm doing wrong :/

06-27-2012, 12:46 PM
nevermind, figured it out - regular textures aren't really good at saving arbitrary float data. I'm using a buffer texture now. Also - position.length() should have been length(position)