texturing using texelFetch()

Question

When I pass non max values into texture buffer, while rendering it draws geometry with colors at max values. I found this issue while using glTexBuffer() API. E.g. Let’s assume my texture data is GLubyte, when I pass any value less than 255, then the color is same as that of drawn with 255, instead of mixture of black and that color. I tried on AMD and nvidia card, but the results are same. Can you tell me where could be going wrong? I am copying my code here: Vert shader: ``` in vec2 a_position; uniform float offset_x; void main() { gl_Position = vec4(a_position.x + offset_x, a_position.y, 1.0, 1.0); } ``` Frag shader: ``` out vec4 Color; uniform isamplerBuffer sampler; uniform int index; void main() { Color=texelFetch(sampler,index); } ``` Code: ``` GLubyte arr[]={128,5,250}; glGenBuffers(1,&bufferid); glBindBuffer(GL_TEXTURE_BUFFER,bufferid); glBufferData(GL_TEXTURE_BUFFER,sizeof(arr),arr,GL_STATIC_DRAW); glBindBuffer(GL_TEXTURE_BUFFER,0); glGenTextures(1, &buffer_texture); glBindT…

Accepted Answer

```
uniform isamplerBuffer sampler;
glTexBuffer(GL_TEXTURE_BUFFER, GL_R8, bufferid);
```

There's your problem: they don't match.

You created the texture's storage as unsigned 8-bit integers, which are normalized to floats upon reading. But you told the shader that you were giving it signed 8-bit integers which will be read as integers, not floats.

You confused OpenGL by being inconsistent. Mismatching sampler types with texture formats yields undefined behavior.

That should be a `samplerBuffer`, not an `isamplerBuffer`.

texturing using texelFetch()

Solution

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