accessing parameters inside a shader

[CGEV]

hi! maybe it's a stupid question, but how do you access a plugin parameter (the "hit surface" plugin) from a shader? let's say i'd like to get the "radius" parameter of a geomParticleSystem from inside a shader, or the "user_float_pp_1" at particle 10 while shading particle 2 ?

thanks!

[vlado]

You can look at the sources of the TexParticleSampler texture in [vraysdk]\samples\vray_plugins\texures\vray_texparticle\tex _particle.cpp, but generally it would be something like:

VR::AColor getTexColor(const VR::VRayContext &rc) {
	VRayPerParticleDataInterface *ppd = (VRayPerParticleDataInterface *)GET_INTERFACE(rc.rayresult.si, EXT_VRAY_PER_PARTICLE_DATA);
	if (ppd) {
		PerParticleColorTypes type=ppc_user1;
		return VR::AColor(ppd->getPerParticleColor(rc, type), 1.0f);
	}
	return VR::AColor(0.0f, 0.0f, 0.0f, 1.0f);
	
}

or

VR::real getTexFloat(const VR::VRayContext &rc) {
	VRayPerParticleDataInterface *ppd = (VRayPerParticleDataInterface *)GET_INTERFACE(rc.rayresult.si, EXT_VRAY_PER_PARTICLE_DATA);
	if (ppd) {
		PerParticleFloatTypes type=ppf_radius;
		return ppd->getPerParticleFloat(rc, type);
	}
	return 0.0f;
}

Best regards,
Vlado

[CGEV]

Hi!

Thanks for the quick answer, maybe my question was not precise enough, but by "radius" i meant the plugin "radius" parameter, not the per particle radius. Also getPerParticleFloat/getPerParticleColor both return the float/color for the "current" particle (the one being shaded), is there a way to get particle 0 float/color while shading particle 10 ?

thanks!

[ivaylo.ivanov]

I think you can get all per particle data using the GeomParticleDataInterface

GeomParticleDataInterface * pdata = (GeomParticleDataInterface *)GET_INTERFACE(rc.rayresult.si, EXT_GEOM_PARTICLE_DATA);
const PerParticleShadeData* pp = pdata ->getPerParticleData();

I don't think you can access the global radius though.

[CGEV]

unfortunately, pdata->getPerParticleData() always seems to return NULL