Hello Johannes,
On 12/10/2010 03:28 AM, Johannes Brunen wrote:
>>> I thought that I would have full GL state infromation inside of a shader
>>> program.
>>
>> no, you can access all the lights properties (position, color, etc.)
>> through the gl_LightSource[i] built in uniform, but the piece of
>> information that is crucially missing is if the light is actually
>> enabled (i.e. if glEnable(GL_LIGHTi) was called).
>
> Unbelievable. Then this information must be provided by addional uniforms.
> Correct?
yes, for lights OpenSG actually does that, the uniforms are called
OSGLightNActive with N = 0..7.
in the GLSL code you just put:
uniform int OSGLightNActive;
and on your fragment shader object you call:
ShaderProgramRefPtr fp = ShaderProgram::createFragmentShader();
fp->addOSGVariable("OSGLightNActive");
There are some other useful "built in" uniforms like that, see
Source/System/State/Shader/Variables/OSGShaderVariableOSG.h for a list.
Cheers,
Carsten
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