improve albedo heuristics and ambient color

#510

game/graphics/sky/sky.cpp

@@ -246,7 +246,7 @@ void Sky::updateLight(const int64_t now) {
 
   Vec3 direct;
   direct  = Vec3(1.0f)   * DirectSunLux;
-  ambient = groundAlbedo * DirectSunLux * aDirect * sunOcclude * 0.05f;// * scale;
+  ambient = groundAlbedo * DirectSunLux * aDirect * sunOcclude * 0.03f;// * scale;
 
   sun.setColor(direct*sunMul);
   ambient = ambient*ambMul;

shader/common.glsl

@@ -20,7 +20,8 @@ const float Fd_LambertInv = (M_PI);
 /* Color value is multiplied to achive adequate albedo and correctness in GI.
  * Need to scale it back, when material receives direct light.
  */
-const float GColorScale   = (1.0/M_PI);
+const float GColorScaleInv = (6);
+const float GColorScale    = (1.0/GColorScaleInv);
 
 float linearDepth(float d, vec3 clipInfo) {
   // z_n * z_f,  z_n - z_f, z_f

shader/lighting/ambient_light.frag

@@ -83,4 +83,5 @@ void main() {
 
   outColor = vec4(color, 1);
   // outColor = vec4(vec3(1-ao), 0);
+  // outColor = vec4(linear, 0);
   }

shader/lighting/irradiance.comp

@@ -27,7 +27,7 @@ void storeSample(vec3 dir, vec3 val) {
 
 vec3 resolveMiss(const vec3 rayOrigin, const vec3 rayDirection) {
   // PERF: need to preload sky lut early in shader
-  return textureSkyLUT(skyLUT, vec3(0,RPlanet,0), rayDirection, scene.sunDir) * scene.GSunIntensity;
+  return textureSkyLUT(skyLUT, vec3(0,RPlanet,0), rayDirection, scene.sunDir) * scene.GSunIntensity * GColorScale;
   }
 
 void gather() {

shader/lighting/light.frag

@@ -87,7 +87,7 @@ void main(void) {
   const vec3 d      = texelFetch(gbufDiffuse, ivec2(gl_FragCoord.xy), 0).xyz;
   const vec3 linear = textureLinear(d.rgb);
 
-  vec3 color = linear*color*Fd_Lambert*light*0.2;
+  vec3 color = linear*color*light*Fd_Lambert*GColorScale*0.5;
   //color *= scene.exposure;
 
   outColor = vec4(color,0.0);

shader/lighting/rt/probe_lighting.comp

@@ -17,7 +17,7 @@ const  uint samplesTotal = gl_WorkGroupSize.x*samplesCount;
 shared vec4 samples[gl_WorkGroupSize.x][3][2]; // 6 Kb
 shared uint shProbeId;
 
-layout(binding = 0, std140) readonly buffer UboScene {
+layout(binding = 0, std140) readonly buffer UboScene { // ubo is broken on NVidia?
   SceneDesc scene;
   };
 layout(binding = 1) uniform writeonly image2D probesLighting;
@@ -68,7 +68,9 @@ void storeSample(vec3 dir, vec4 val) {
     }
   }
 
-vec3 resolveHit(const vec3 rayOrigin, const vec3 rayDirection, float rayT, vec3 albedo, vec3 normal, bool opaque, float shMap) {
+vec3 resolveHit(const vec3 rayOrigin, const vec3 rayDirection, float rayT, vec3 normal, bool opaque, float shMap) {
+  // return 1.0 * scene.ambient;
+
   float dt = dot(normal, scene.sunDir);
   if(!opaque) {
     // atificial lit on vegetation, as RT can't capture small bright light leaks from the trees
@@ -78,9 +80,9 @@ vec3 resolveHit(const vec3 rayOrigin, const vec3 rayDirection, float rayT, vec3
 
   const float lambert = max(0, dt); //max(opaque ? 0 : 0.2, dt);
   const float shadow  = max(0, shMap);
-  const vec3  lcolor  = scene.sunColor * Fd_Lambert * lambert * shadow;
+  const vec3  lcolor  = scene.sunColor * Fd_Lambert * lambert * shadow * GColorScale;
 
-  return albedo*lcolor;
+  return lcolor;
   //return scene.sunColor * scene.ambient;
   }
 
@@ -90,7 +92,7 @@ vec3 resolveMiss(const vec3 rayOrigin, const vec3 rayDirection) {
   }
 
 vec3 resolveSecondBounce(vec3 pos, vec3 norm, uint selfProbeId) {
-  return 4.0 * scene.ambient * Fd_LambertInv;
+  return scene.ambient;
 
   // doesn't look coherent yet - need to keep offscreen data for long term
   const ivec3 gridPos = ivec3(round(pos/(probeGridStep*1)));
@@ -140,20 +142,24 @@ vec4 processSample(const vec3 rayOrigin, const vec3 rayDirection, uint probeId,
   const bool opaque  = (bits & 0x1)!=0;
   const bool semiSky = (bits & 0x8)!=0;
 
-  const vec3  albedo  = textureLinear(diff.rgb) * Fd_Lambert;
+  const vec3  albedo  = textureLinear(diff.rgb);
   const vec3  norm    = normalize(nr.xyz*2.0-vec3(1));
 
   const float rayT    = rt * probeRayDistance;
   const vec3  pos     = rayOrigin + rayT*rayDirection;
 
-  const vec3  bounce2 = resolveSecondBounce(pos, -rayDirection, probeId);
-
   // TODO: rt-shadow lighting ?
   vec4  shCoord = scene.viewShadow[1]*vec4(pos,1);
   float shadow  = shadowFactor(shCoord);
 
-  vec3 hit = resolveHit(rayOrigin, rayDirection, rayT, albedo, norm, opaque, shadow);
-  hit += albedo*bounce2;
+  vec3 hit = vec3(0);
+  hit += albedo * resolveHit(rayOrigin, rayDirection, rayT, norm, opaque, shadow);
+  hit += albedo * resolveSecondBounce(pos, -rayDirection, probeId);
+  // hit += albedo * resolveHit(rayOrigin, rayDirection, rayT, norm, opaque, shadow);
+  // hit += albedo * resolveSecondBounce(pos, -rayDirection, probeId) / max(1.0 - albedo, 0.1);
+
+  // hit = resolveSecondBounce(pos, -rayDirection, probeId);
+
   if(semiSky) {
     // avoid pitch-black lighting in forrest
     hit = (hit*0.25 + resolveMiss(rayOrigin, rayDirection)*0.75);

shader/lighting/sky_exposure.comp

@@ -111,7 +111,7 @@ void main() {
     const vec3 sunColor = scene.sunColor * tr * clouds;
     const vec3 ambient  = scene.ambient  * tr;//  * clouds;
 
-    vec3  light = sunColor*GColorScale*1.5 + ambient + skyIrradiance();
+    vec3  light = sunColor*Fd_Lambert*1.5 + ambient + skyIrradiance();
     float lum   = (vmax+vmin) * 0.5 * scene.GSunIntensity;
     //lum = dot(light, vec3(1.0/3.0));
     lum = dot(light, vec3(0.2125, 0.7154, 0.0721))*0.6 + lum*0.4;

shader/lighting/tonemapping.frag

@@ -113,7 +113,7 @@ void main() {
 
   vec3  color      = textureLod(textureD, uv, 0).rgb;
   {
-    // outColor = vec4(color, 1.0);
+    // outColor = vec4(srgbEncode(color), 1);
     // return;
   }
 

shader/lighting/tonemapping.glsl

@@ -46,7 +46,7 @@ vec3 textureLinear(vec3 rgb) {
   // return vec3(0.33, 0.34, 0.18); // leaves
   // return vec3(0.9);
   // return acesTonemapInv(linear*0.8);
-  return acesTonemapInv(linear*0.78+0.001)*Fd_LambertInv; // adjusted to have 'realistic' albedo values
+  return acesTonemapInv(linear*0.78+0.001)*GColorScaleInv; // adjusted to have 'realistic' albedo values
 #endif
   }