glm::vec3 VKTS_APIENTRY renderLambert(const IImageDataSP& cubeMap, const VkFilter filter, const uint32_t mipLevel, const glm::vec2& randomPoint, const glm::mat3& basis)
{
if (!cubeMap.get() || cubeMap->getArrayLayers() != 6)
{
return glm::vec3(0.0f, 0.0f, 0.0f);
}
glm::vec3 LtangentSpace = renderGetCosineWeightedVector(randomPoint);
// Transform light ray to world space.
glm::vec3 L = basis * LtangentSpace;
return glm::vec3(cubeMap->getSampleCubeMap(L.x, L.y, L.z, filter, mipLevel));
}
glm::vec3 VKTS_APIENTRY renderCookTorrance(const IImageDataSP& cubeMap, const VkFilter filter, const uint32_t mipLevel, const glm::vec2& randomPoint, const glm::mat3& basis, const glm::vec3& N, const glm::vec3& V, const float roughness)
{
if (!cubeMap.get() || cubeMap->getArrayLayers() != 6)
{
return glm::vec3(0.0f, 0.0f, 0.0f);
}
glm::vec3 HtangentSpace = renderGetGGXWeightedVector(randomPoint, roughness);
// Transform H to world space.
glm::vec3 H = basis * HtangentSpace;
// Note: reflect takes incident vector.
glm::vec3 L = glm::reflect(-V, H);
return glm::vec3(cubeMap->getSampleCubeMap(L.x, L.y, L.z, filter, mipLevel));
}
glm::vec3 VKTS_APIENTRY renderOrenNayar(const IImageDataSP& cubeMap, const VkFilter filter, const uint32_t mipLevel, const glm::vec2& randomPoint, const glm::mat3& basis, const glm::vec3& N, const glm::vec3& V, const float roughness)
{
if (!cubeMap.get() || cubeMap->getArrayLayers() != 6)
{
return glm::vec3(0.0f, 0.0f, 0.0f);
}
glm::vec3 LtangentSpace = renderGetCosineWeightedVector(randomPoint);
// Transform light ray to world space.
glm::vec3 L = basis * LtangentSpace;
float NdotL = glm::dot(N, L);
float NdotV = glm::dot(N, V);
float angleVN = acosf(NdotV);
float angleLN = acosf(NdotL);
float alpha = glm::max(angleVN, angleLN);
float beta = glm::min(angleVN, angleLN);
float gamma = glm::dot(V - N * NdotV, L - N * NdotL);
float roughnessSquared = roughness * roughness;
float A = 1.0f - 0.5f * (roughnessSquared / (roughnessSquared + 0.57f));
float B = 0.45f * (roughnessSquared / (roughnessSquared + 0.09f));
float C = sinf(alpha) * tanf(beta);
float Lr = glm::max(0.0f, NdotL) * (A + B * glm::max(0.0f, gamma) * C);
return glm::vec3(cubeMap->getSampleCubeMap(L.x, L.y, L.z, filter, mipLevel)) * Lr;
}