After working on PBR for a while i noticed so major performance problems, initially i assumed it to be part of how i was implementing IBL but after checking the implementation with other engines i found that it is not a problem with the the technique. I came to the conclusion it is either an issue with Urho3D’s or i was implementing it into the wrong area of the shader for the desired affect. Any help with the problem would greatly.
Entry to the IBL is at the bottom of the code
Lighting.hlsl
[code] float radicalInverse_VdC(uint bits)
{
bits = (bits << 16u) | (bits >> 16u);
bits = ((bits & 0x55555555u) << 1u) | ((bits & 0xAAAAAAAAu) >> 1u);
bits = ((bits & 0x33333333u) << 2u) | ((bits & 0xCCCCCCCCu) >> 2u);
bits = ((bits & 0x0F0F0F0Fu) << 4u) | ((bits & 0xF0F0F0F0u) >> 4u);
bits = ((bits & 0x00FF00FFu) << 8u) | ((bits & 0xFF00FF00u) >> 8u);
return float(bits) * 2.3283064365386963e-10; // / 0x100000000
}
float2 Hammersley(uint i, uint n)
{
return float2((float)i / (float)n, radicalInverse_VdC(i));
}
float3 ImportanceSampleGGX(float2 Xi, float Roughness, float3 N)
{
float a = Roughness * Roughness;
float Phi = 2 * 3.14159 * Xi.x;
float CosTheta = sqrt((1 - Xi.y) / (1 + (a*a - 1) * Xi.y));
float SinTheta = sqrt(1 - CosTheta * CosTheta);
float3 H = 0;
H.x = SinTheta * cos(Phi);
H.y = SinTheta * sin(Phi);
H.z = CosTheta;
float3 UpVector = abs(N.z) < 0.999 ? float3(0, 0, 1) : float3(1, 0, 0);
float3 TangentX = normalize(cross(UpVector, N));
float3 TangentY = cross(N, TangentX);
// Tangent to world space
return TangentX * H.x + TangentY * H.y + N * H.z;
}
float GGX(float nDotV, float a)
{
float aa = a*a;
float oneMinusAa = 1 - aa;
float nDotV2 = 2 * nDotV;
float root = aa + oneMinusAa * nDotV * nDotV;
return nDotV2 / (nDotV + sqrt(root));
}
float G_Smith(float a, float nDotV, float nDotL)
{
return GGX(nDotL, a * a) * GGX(nDotV, a * a);
}
float3 PrefilterEnvMap(float Roughness, float3 R)
{
float3 N = R;
float3 V = R;
float3 PrefilteredColor = 0;
const uint NumSamples = 1;
float TotalWeight = 0.0000001f;
for (uint i = 0; i < NumSamples; i++)
{
float2 Xi = Hammersley(i * 2 + 0, NumSamples);
float3 H = ImportanceSampleGGX(Xi, Roughness, N);
float3 L = 2 * dot(V, H) * H - V;
float NoL = saturate(dot(N, L));
if (NoL > 0)
{
PrefilteredColor += SampleCubeLOD(ZoneCubeMap, float4(L, 0)).rgb * NoL;
TotalWeight += NoL;
}
}
return PrefilteredColor / TotalWeight;
}
float3 ApproximateSpecularIBL(float3 SpecularColor, float Roughness, float3 N, float3 V)
{
/* float NoV = saturate(dot(N, V));*/
float3 R = 2 * dot(V, N) * N - V;
float3 PrefilteredColor = PrefilterEnvMap(Roughness, R);
//float2 envBRDF = IntegrateBRDF(Roughness, NoV);
return PrefilteredColor * (SpecularColor);
}[/code]
LitSolid.hlsl
[code] #elif defined(DEFERRED)
// Fill deferred G-buffer
float specIntensity = specColor.g;
float specPower = cMatSpecColor.a / 255.0;
float3 finalColor = iVertexLight * diffColor.rgb;
#ifdef AO
#ifdef IBL
const float aoFactor = Sample2D(EmissiveMap, iTexCoord).r;
#else
// If using AO, the vertex light ambient is black, calculate occluded ambient here
finalColor += Sample2D(EmissiveMap, iTexCoord2).rgb * cAmbientColor * diffColor.rgb;
#endif
#endif
#if defined(PBR) && defined(IBL)
const float3 toCamera = normalize(iWorldPos.xyz - cCameraPosPS);
const float3 reflection = normalize(reflect(toCamera, normal));
float3 cubeColor = iVertexLight.rgb;
float3 iblColor = ApproximateSpecularIBL( specColor, normal, -toCamera);
float horizonOcclusion = 1.3;
float horizon = saturate(1 + horizonOcclusion * dot(reflection, normal));
horizon *= horizon;
#ifdef AO
finalColor += LinearFromSRGB(iblColor * aoFactor * horizon * cubeColor);
#else
finalColor += LinearFromSRGB(iblColor * horizon * cubeColor);
#endif
#endif[/code]
