vk: rt: slightly cleanup bounce loop shader code

ref/vk/shaders/bounce.comp

@@ -65,7 +65,8 @@ bool getHit(vec3 origin, vec3 direction, inout RayPayloadPrimary payload) {
  //| gl_RayFlagsTerminateOnFirstHitEXT
  //| gl_RayFlagsSkipClosestHitShaderEXT
  ;
- const float L = 10000.; // TODO Why 10k?
+
+ const float L = 10000.; // TODO Why 10k? Use the real max distance, as in ray_primary.comp
  rayQueryInitializeEXT(rq, tlas, flags, GEOMETRY_BIT_OPAQUE | GEOMETRY_BIT_ALPHA_TEST, origin, 0., direction, L);
  while (rayQueryProceedEXT(rq)) {
  if (0 != (rayQueryGetRayFlagsEXT(rq) & gl_RayFlagsOpaqueEXT))
@@ -89,11 +90,19 @@ bool getHit(vec3 origin, vec3 direction, inout RayPayloadPrimary payload) {
  }
  }
 
- if (rayQueryGetIntersectionTypeEXT(rq, true) != gl_RayQueryCommittedIntersectionTriangleEXT)
+ if (rayQueryGetIntersectionTypeEXT(rq, true) != gl_RayQueryCommittedIntersectionTriangleEXT) {
+ payload.hit_t.w = L;
+ payload.emissive.rgb = sampleSkybox(direction);
  return false;
+ }
 
  primaryRayHit(rq, payload);
- //L = rayQueryGetIntersectionTEXT(rq, true);
+ const bool hit_skybox = payload.hit_t.w < 0.;
+ if (hit_skybox) {
+ payload.hit_t.w *= -1;
+ return false;
+ }
+
  return true;
 }
 const int INDIRECT_SCALE = 2;
@@ -104,21 +113,20 @@ struct MaterialEx {
  //TODO float alpha;
 };
 
-int max_bounces = 1;
-
+const int kMaxBounces = 1;
 const vec3 kThrougputExtinctionThreshold = vec3(1e-3);
+const float kRayNormalOffsetFudge = .01;
 
 ivec2 pix;
 void computeBounces(MaterialEx mat, vec3 pos, vec3 direction, inout vec3 diffuse, inout vec3 specular) {
- const float ray_normal_fudge = .01;
  vec3 throughput = vec3(1.);
- vec3 bounce_direction;
 
- //const int max_bounces = 2;
  // TODO split into two distinct passes, see #734
  int first_brdf_type = BRDF_TYPE_NONE;
 
- for (int i = 0; i < max_bounces; ++i) {
+ for (int i = 0; i < kMaxBounces; ++i) {
+ vec3 bounce_direction;
+
  // TODO blue noise
  const vec2 rnd = vec2(rand01(), rand01());
  const int brdf_type = brdfGetSample(rnd, mat.prop, -direction, mat.geometry_normal, mat.shading_normal/* TODO, mat.base_color_a.a*/, bounce_direction, throughput);
@@ -145,7 +153,7 @@ void computeBounces(MaterialEx mat, vec3 pos, vec3 direction, inout vec3 diffuse
  }
 */
 
- if (all(lessThan(throughput,kThrougputExtinctionThreshold)))
+ if (all(lessThan(throughput, kThrougputExtinctionThreshold)))
  return;
 
  if (first_brdf_type == BRDF_TYPE_NONE)
@@ -158,16 +166,16 @@ void computeBounces(MaterialEx mat, vec3 pos, vec3 direction, inout vec3 diffuse
  payload.normals_gs = vec4(0.);
 
  vec3 contribution = vec3(0.);
- pos += mat.geometry_normal * ray_normal_fudge;
+ pos += mat.geometry_normal * kRayNormalOffsetFudge;
+
+ vec3 hit_color = vec3(0.);
  const bool did_hit = getHit(pos, bounce_direction, payload);
- bool hit_skybox = false;
+ MaterialProperties hit_material;
+ const vec3 hit_pos = payload.hit_t.xyz;
+ const vec3 hit_shading_normal = normalDecode(payload.normals_gs.zw);
  if (did_hit) {
- const vec3 hit_pos = payload.hit_t.xyz;
- const vec3 hit_shading_normal = normalDecode(payload.normals_gs.zw);
-
  vec3 ldiffuse = vec3(0.);
  vec3 lspecular = vec3(0.);
- MaterialProperties hit_material;
  hit_material.base_color = payload.base_color_a.rgb;
  hit_material.metalness = payload.material_rmxx.g;
  hit_material.roughness = payload.material_rmxx.r;
@@ -197,46 +205,34 @@ void computeBounces(MaterialEx mat, vec3 pos, vec3 direction, inout vec3 diffuse
  lspecular = vec3(0.);
  }
 
- const vec3 background = mixFinalColor(payload.base_color_a.rgb, ldiffuse, lspecular, hit_material.metalness);
- // OLD
- //vec3 background = payload.base_color_a.rgb * ldiffuse;
- //background += lspecular * mix(vec3(1.), payload.base_color_a.rgb, hit_material.metalness);
-
- const vec4 blend = traceLegacyBlending(pos, bounce_direction, payload.hit_t.w);
- contribution = throughput*(SRGBtoLINEAR(blend.rgb) + background * blend.a);
-
- // FIXME check this very early before doing any lighting stuff
- hit_skybox = payload.hit_t.w < 0.;
- if (hit_skybox)
- /* FIXME: also if last bounce (i.e. w/o direct light sampling) or */
- contribution += throughput * payload.emissive.rgb;
-
- // Prepare next bounce state
- pos = hit_pos;
- direction = bounce_direction;
- mat.prop = hit_material;
- mat.geometry_normal = normalDecode(payload.normals_gs.xy);
- mat.shading_normal = hit_shading_normal;
-
- if (brdf_type == BRDF_TYPE_DIFFUSE) {
- const vec3 diffuse_color = mix(payload.base_color_a.rgb, vec3(0.), payload.material_rmxx.g);
- throughput *= diffuse_color;
- }
- } else {
- // FIXME this no-hit path should still do traceLegacyBlending()
- contribution = throughput * sampleSkybox(bounce_direction);
- hit_skybox = true;
- } // not hit
+ hit_color = mixFinalColor(payload.base_color_a.rgb, ldiffuse, lspecular, hit_material.metalness);
+ } /* if (did_hit) */ else {
+ // not hit -- hit sky
+ hit_color = payload.emissive.rgb;
+ }
+
+ const vec4 blend = traceLegacyBlending(pos, bounce_direction, payload.hit_t.w);
+ contribution = throughput * (SRGBtoLINEAR(blend.rgb) + hit_color * blend.a);
 
  if (first_brdf_type == BRDF_TYPE_DIFFUSE)
  diffuse += contribution;
  else
  specular += contribution;
 
- if (hit_skybox) {
+ if (!did_hit)
  break;
- }
 
+ // Prepare next bounce state
+ pos = hit_pos;
+ direction = bounce_direction;
+ mat.prop = hit_material;
+ mat.geometry_normal = normalDecode(payload.normals_gs.xy);
+ mat.shading_normal = hit_shading_normal;
+
+ if (brdf_type == BRDF_TYPE_DIFFUSE) {
+ const vec3 diffuse_color = mix(payload.base_color_a.rgb, vec3(0.), payload.material_rmxx.g);
+ throughput *= diffuse_color;
+ }
  } // for bounces
 }
 
@@ -274,8 +270,6 @@ void main() {
  mat.geometry_normal = geometry_normal;
  mat.shading_normal = shading_normal;
 
- //max_bounces = (pix.x > res.x / 2.) ? 2 : 1;
-
  computeBounces(mat, pos_t.xyz, direction, diffuse, specular);
  }