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#ifndef SAMPLE_LIGHT_GLSLLIB
#define SAMPLE_LIGHT_GLSLLIB
#define MAX_NUM_SHADOWS 8
#ifndef UIC_ENABLE_SSM
#define UIC_ENABLE_SSM 0
#endif
#include "SSAOCustomMaterial.glsllib"
#if UIC_ENABLE_SSM
#include "shadowMapping.glsllib"
#endif
#include "funcsampleLightVars.glsllib"
#if UIC_ENABLE_SSM
uniform sampler2D shadowMaps[MAX_NUM_SHADOWS];
uniform samplerCube shadowCubes[MAX_NUM_SHADOWS];
uniform int uNumShadowMaps;
uniform int uNumShadowCubes;
#endif
void sampleLight(in LightSource light,
in vec3 pos,
out vec3 wi,
out vec3 opAmbient,
out vec3 opDiffuse,
out vec3 opSpecular)
{
float att = 1.0;
if (light.position.w == 0.0f) // directional light
{
wi = normalize(light.position.xyz);
#if UIC_ENABLE_SSM
if ( light.shadowIdx >= 0 )
att *= sampleOrthographic( shadowMaps[light.shadowIdx], light.shadowControls, light.shadowView, pos, vec2(1.0, light.shadowControls.z) );
#endif
}
else if (light.width > 0.01f && light.height > 0.01f) // area light
{
// This approach is based on the 1994 Tech Report by James Arvo --
// The Irradiance Jacobian for Partially Occluded Polyhedral Sources
// The nice thing about this approach is that it extends to arbitrary geometry (if we choose to support it),
// and accounts for distance & geometric attenuation automatically.
// Downsides -- only really works for diffuse reflection, does not account properly for an area light that
// intersects its receiver, in which case it illuminates as if the light source is two-sided Lambertian emitter.
vec3 v0 = light.position.xyz - (light.right.xyz * light.width * 0.5) - (light.up.xyz * light.height * 0.5);
vec3 v1 = light.position.xyz - (light.right.xyz * light.width * 0.5) + (light.up.xyz * light.height * 0.5);
vec3 v2 = light.position.xyz + (light.right.xyz * light.width * 0.5) + (light.up.xyz * light.height * 0.5);
vec3 v3 = light.position.xyz + (light.right.xyz * light.width * 0.5) - (light.up.xyz * light.height * 0.5);
v0 = normalize( v0 - pos ); v1 = normalize( v1 - pos ); v2 = normalize( v2 - pos ); v3 = normalize( v3 - pos );
float a01 = acos( clamp( dot(v0, v1), -1.0, 1.0 ) );
float a12 = acos( clamp( dot(v1, v2), -1.0, 1.0 ) );
float a23 = acos( clamp( dot(v2, v3), -1.0, 1.0 ) );
float a30 = acos( clamp( dot(v3, v0), -1.0, 1.0 ) );
wi = vec3( 0.0 );
wi -= normalize(cross( v0, v1 )) * a01;
wi -= normalize(cross( v1, v2 )) * a12;
wi -= normalize(cross( v2, v3 )) * a23;
wi -= normalize(cross( v3, v0 )) * a30;
att = length(wi) * 0.15915494309; // solid angle / 2*pi
wi = normalize(wi);
att *= clamp( dot( pos - light.position.xyz, light.direction.xyz ), 0.0, 1.0 );
#if UIC_ENABLE_SSM
if ( light.shadowIdx >= 0 )
att *= sampleCubemap( shadowCubes[light.shadowIdx], light.shadowControls, light.shadowView, light.position.xyz, pos, vec2(1.0, light.shadowControls.z) );
#endif
}
else // point or spot light
{
wi = light.position.xyz - pos;
float dist = length(wi);
wi = wi / dist; // == normalize(wi);
att = 1.0f / (light.constantAttenuation + (light.linearAttenuation + light.quadraticAttenuation * dist) * dist);
/*
if (light.spotCutoff < 180.0f) // spot light
{
float spot = max(0.0f, dot(wi, -light.direction.xyz));
att *= (spot >= cos(light.spotCutoff * PI / 180.0f)) ? pow(spot, light.spotExponent) : 0.0f;
}
*/
#if UIC_ENABLE_SSM
if ( light.shadowIdx >= 0 )
att *= sampleCubemap( shadowCubes[light.shadowIdx], light.shadowControls, light.shadowView, light.position.xyz, pos, vec2(1.0, light.shadowControls.z) );
#endif
}
float shadow = customMaterialShadow( -light.direction.xyz, pos );
opAmbient = att * light.ambient.xyz;
opDiffuse = att * shadow * light.diffuse.xyz;
opSpecular = att * shadow * light.specular.xyz;
}
#include "sampleArea.glsllib"
#endif
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