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#version 330 core
in vec3 Normal;
in vec3 FragPos;
in vec2 UV;
out vec4 FragColor;
uniform vec3 lightPos;
uniform vec3 lightColor;
uniform vec3 objectColor;
uniform vec3 viewPos;
uniform sampler2D irradianceTexture;
uniform int screenWidth;
uniform int screenHeight;
uniform int renderState;
uniform vec2 samplePositions[13];
uniform vec3 sampleWeights[13];
uniform float transmittanceScale;
void main()
{
// light the model
vec3 norm = normalize(Normal);
vec3 lightDir = normalize(lightPos - FragPos);
float diff = max(dot(norm, lightDir), 0.0);
vec3 diffuse = diff * lightColor;
float ambientStrength = 0.1;
vec3 ambient = ambientStrength * lightColor;
float specularStrength = 0.5;
vec3 viewDir = normalize(viewPos - FragPos);
vec3 reflectDir = reflect(-lightDir, norm);
float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32);
vec3 specular = specularStrength * spec * lightColor;
vec3 result = vec3((ambient + diffuse + specular) * objectColor);
// sample irradiance as distance to light combined with angle to the light
// with a Gaussian kernel
vec3 result2 = vec3(0, 0, 0);
for (int i = 0; i < 13; i++) {
vec2 sampleCoords = UV + samplePositions[i] * vec2(1.0/screenWidth, 1.0/screenHeight);
//vec4 sample = texture(irradianceTexture, sampleCoords)
// * texture(shadowmapTexture, sampleCoords);
vec3 sample = vec3(texture(irradianceTexture, sampleCoords)) * diff;
vec3 weight = sampleWeights[i];
result2 += sample * weight;
}
// multiply to apply irradiance, sqrt to get values between 0 and 1
result = sqrt(result * result2);
// sample texture to get distance from light
vec4 t = texture(irradianceTexture, UV);
float BacksideIrradiance = t.r; //*100 + t.g + t.b/100;
// and calculate world pos
vec3 Backside = (lightPos + (normalize(FragPos - lightPos) * BacksideIrradiance));
// add translucency by amplifying color inverse to the thickness
// (1 - diff) is part of the irradiance term,
// if the light hits the object straight at 90°
// most light is received
float distanceToBackside = length(FragPos - Backside);
if (distanceToBackside != 0)
result += objectColor * exp(2 / pow(distanceToBackside, 0.6)) * transmittanceScale * (1 - diff);
FragColor = vec4(result, 1);
}
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