Hi Terry,
I believe uniform array support in OpenGL is still in its early
stages, constant indices seem ok, but not elements that have
variables. Mike Weiblen wrote some shaders a while back to test the
array support which revealled this problem, and I've seen references
to similar problems on opengl.org forums too.
However, I haven't seen any crashes, but then I haven't tested the
array support too much in anger. I believe osgCharacter has uniform
array usage, so perhaps this could be used as a test platform too.
Robert.
On 7/23/06, Terry Welsh <[EMAIL PROTECTED]> wrote:
Hi,
This is probably an OpenGL driver bug, but maybe I'm just setting something
up wrong. Has anyone else tried to use an array of samplers in a GLSL
shader? I'm setting up my array of samplers like this:
shadowmapUniform = new
Uniform(Uniform::SAMPLER_2D_SHADOW, "shadowmap",
NUM_SHADOW_MAPS);
for(i=0; i<NUM_SHADOW_MAPS; i++){
sceneSS->setTextureAttributeAndModes(i+FIRST_SHADOW_TEX_UNIT,
shadowmap[i].get(), StateAttribute::ON);
shadowmapUniform->setElement(i, i+FIRST_SHADOW_TEX_UNIT);
}
sceneSS->addUniform(shadowmapUniform.get());
The fragment shaders defines the samplers like this:
uniform sampler2DShadow shadowmap[4];
And it accesses one of them like this:
float shadow = shadow2D(shadowmap[0], lsPosition).r;
And then I get a segmentation fault. If I don't call the shadow2D function
in the shader, everything keeps running and I just don't get any shadows.
Has anyone else had any luck doing anything like this before, or does this
look like a driver bug? I'm using an NVidia 6800GT on Linux with the 8762
driver.
--
Terry Welsh - mogumbo 'at' gmail.com
www.reallyslick.com | www.mogumbo.com
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