gl_LightSource[i] and catalyst 4.10

OpenGL
1

With catalyst 4.10 and something like the following I get this error:

for (int i=0;i<8;i++)
  color+=gl_LightSource[i].diffuse

ERROR: 0:39: '[' :  array must be redeclared with a size before being indexed with a variable

If I use my own declared uniform array in the same way it works fine, and the compiler does not allow me to redeclare the gl_LightSource array. Ofcourse constant indices works fine too (and IMHO this kind of indexing is quite “constant”/unrollable too - as least as long it looks like this).
Can I somehow set the size of the gl_LightSource array or is it simply a driver bug?

2

This is a compiler issue. ATI hardware is not able to run dynamic loops so the compiler gives you an error because you use a loop. It seems that ATIs compiler doesn’t check if the loop can be statically unrolled as it is the case in you example.

3

No, It is able to do dynamic branching in the vertex shader (and also able to unroll loops in the fragment shader), and as said, if I use my own similar uniform array instead of gl_LightSource it works fine, even with more dynamic indexing. So unless I am missing something it seems there is something wrong with the built in gl_LightSource declaration.

4

I haven’t been able to reproduce the problem. Could you post the entire shader and the fragment shader as well?

5

Vertex shader:

void main()
{	
  gl_Position = ftransform(); 
  for (int i=0;i<8;i++)
    gl_FrontColor+=gl_LightSource[i].diffuse;
}

Fragment shader:

void main()
{
	gl_FragColor = gl_Color;
}

While for instance this vertex shader compiles fine:

uniform gl_LightSourceParameters my_LightSource[gl_MaxLights];

void main()
{	
  gl_Position = ftransform(); 
  for (int i=0;i<8;i++)
    gl_FrontColor+=my_LightSource[i].diffuse;
}

This particular example is on the 8.07/4702 drivers

6

Well, it works just fine for me so I don’t know what’s wrong. Do you have a sample application you could send me at epersson ‘at’ ati.com?

7

Hi,

I get excatly the same problem with two different computers
1- Ati X800XT 4.11
2- Ati X600XT 4.12

Any Idea ?
Thanks
Cedric

8

It turned out that it works for the very first shader compilation in a context but not after that, and it’s still there in the 8.09 beta.

9

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