Added absorption

Author: knightcrawler25

src/Main.cpp

@@ -336,9 +336,9 @@ void MainLoop(void* arg)
             // Material Properties
             Vec3 *albedo   = &scene->materials[scene->meshInstances[selectedInstance].materialID].albedo;
             Vec3 *emission = &scene->materials[scene->meshInstances[selectedInstance].materialID].emission;
+            Vec3 *extinction = &scene->materials[scene->meshInstances[selectedInstance].materialID].extinction;
 
             objectPropChanged |= ImGui::ColorEdit3("Albedo", (float*)albedo, 0);
-            //objectPropChanged |= ImGui::ColorEdit3("Emission", (float*)emission, 0);
             objectPropChanged |= ImGui::SliderFloat("Metallic",  &scene->materials[scene->meshInstances[selectedInstance].materialID].metallic, 0.001f, 1.0f);
             objectPropChanged |= ImGui::SliderFloat("Roughness", &scene->materials[scene->meshInstances[selectedInstance].materialID].roughness, 0.001f, 1.0f);
             objectPropChanged |= ImGui::SliderFloat("Specular", &scene->materials[scene->meshInstances[selectedInstance].materialID].specular, 0.001f, 1.0f);
@@ -351,6 +351,7 @@ void MainLoop(void* arg)
             objectPropChanged |= ImGui::SliderFloat("ClearcoatGloss", &scene->materials[scene->meshInstances[selectedInstance].materialID].clearcoatGloss, 0.001f, 1.0f);
             objectPropChanged |= ImGui::SliderFloat("Transmission", &scene->materials[scene->meshInstances[selectedInstance].materialID].transmission, 0.001f, 1.0f);
             objectPropChanged |= ImGui::SliderFloat("Ior", &scene->materials[scene->meshInstances[selectedInstance].materialID].ior, 1.0f, 2.0f);
+            objectPropChanged |= ImGui::ColorEdit3("Extinction", (float*)extinction, 0);
 
             // Transforms Properties
             ImGui::Separator();

src/core/Material.h

@@ -57,13 +57,11 @@ namespace GLSLPT
 
             transmission  = 0.0f;
             ior           = 1.45f;
-            unused1       = 0.0f;
-            unused2       = 0.0f;
+            extinction    = Vec3(0.0f, 0.0f, 0.0f);
 
             albedoTexID             = -1.0f;
             metallicRoughnessTexID  = -1.0f;
             normalmapTexID          = -1.0f;
-            unused3                 =  0.0f;
         };
 
         Vec3 albedo;
@@ -84,12 +82,10 @@ namespace GLSLPT
 
         float transmission;
         float ior;
-        float unused1;
-        float unused2;
+        Vec3 extinction;
 
         float albedoTexID;
         float metallicRoughnessTexID;
         float normalmapTexID;
-        float unused3;
     };
 }

src/loaders/Loader.cpp

@@ -111,7 +111,7 @@ namespace GLSLPT
                     sscanf(line, " clearcoatGloss %f", &material.clearcoatGloss);
                     sscanf(line, " transmission %f", &material.transmission);
                     sscanf(line, " ior %f", &material.ior);
-
+                    sscanf(line, " extinction %f %f %f", &material.extinction.x, &material.extinction.y, &material.extinction.z);
                     sscanf(line, " albedoTexture %s", albedoTexName);
                     sscanf(line, " metallicRoughnessTexture %s", metallicRoughnessTexName);
                     sscanf(line, " normalTexture %s", normalTexName);

src/shaders/common/disney.glsl

@@ -150,8 +150,14 @@ vec3 DisneyEval(in Ray ray, inout State state, in vec3 bsdfDir)
     // TODO: Fix bsdf for microfacet transmission
     if (state.mat.transmission > 0.0)
     {
+        vec3 transmittance = vec3(1.0);
+        vec3 extinction = log(state.mat.extinction);
+
+        if (dot(state.normal, state.ffnormal) < 0.0)
+            transmittance = exp(extinction * state.hitDist);
+
         if (dot(N, L) <= 0.0)
-            bsdf = state.mat.albedo / abs(NDotL);
+            bsdf = state.mat.albedo * transmittance / abs(NDotL);
         else
         {
             float a = max(0.001, state.mat.roughness);

src/shaders/common/globals.glsl

@@ -59,7 +59,8 @@ struct Material
     float clearcoatGloss; 
     float transmission; 
     float ior; 
-    vec4 texIDs;
+    vec3 extinction;
+    vec3 texIDs;
 };
 
 struct Camera 

src/shaders/common/pathtrace.glsl

@@ -72,7 +72,7 @@ void GetMaterialsAndTextures(inout State state, in Ray r)
     vec4 param3 = texelFetch(materialsTex, ivec2(index * 6 + 2, 0), 0);
     vec4 param4 = texelFetch(materialsTex, ivec2(index * 6 + 3, 0), 0);
     vec4 param5 = texelFetch(materialsTex, ivec2(index * 6 + 4, 0), 0);
-    mat.texIDs  = texelFetch(materialsTex, ivec2(index * 6 + 5, 0), 0);
+    vec4 param6 = texelFetch(materialsTex, ivec2(index * 6 + 5, 0), 0);
 
     mat.albedo         = param1.xyz;
     mat.specular       = param1.w;
@@ -93,6 +93,9 @@ void GetMaterialsAndTextures(inout State state, in Ray r)
     mat.transmission   = param5.x;
     mat.ior            = param5.y;
 
+    mat.extinction     = vec3(param5.zw, param6.x);
+    mat.texIDs         = vec3(param6.yzw);
+
     vec2 texUV = state.texCoord;
     texUV.y = 1.0 - texUV.y;