Convert fake origins code to tangent space

1 files changed, 54 insertions, 5 deletions

diff --git a/fog.cginc b/fog.cginc
index 7f34795..6e471e9 100644
--- a/fog.cginc
+++ b/fog.cginc
@@ -9,6 +9,7 @@
 #if defined(_RAYMARCHED_FOG)
 
 struct FogParams {
+    float3 color;
     float steps;
     float density;
     float y_cutoff;
@@ -24,8 +25,47 @@ struct FogParams {
     float height_density_start;
     float height_density_half_life;
 #endif
+#if defined(_CUSTOM30_FOG_HEIGHT_DENSITY_MINIMUM)
+    float height_density_minimum;
+#endif
+#if defined(_RAYMARCHED_FOG_EMITTER_TEXTURE)
+    texture2D emitter_texture;
+    float4 emitter_texture_texelsize;
+    float3 emitter_world_pos;
+    float3 emitter_normal;
+    float3 emitter_tangent;
+    float3 emitter_normal_x_tangent;
+    float2 emitter_scale;  // [tangent scale in meters, bitangent scale in meters]
+    float2 emitter_scale_rcp;
+#endif
 };
 
+#if defined(_RAYMARCHED_FOG_EMITTER_TEXTURE)
+// Returns weighted color
+float3 getEmitterData(FogParams p, float3 pp)
+{
+  // Using identity a_parallel_to_b = (dot(a, b) / dot(b, b)) * b
+  //   float3 along_tangent = dot(p - em_loc, em_tangent) * em_tangent;
+  //   float3 along_normal_x_tangent = dot(p - em_loc, em_normal_x_tangent) *
+  //       em_normal_x_tangent;
+  // Given that em_tangent and em_normal_x_tangent are normalized, and the fact
+  // that we really want uvs, we can simplify this:
+  float2 uv = float2(dot(pp - p.emitter_world_pos, p.emitter_normal_x_tangent), dot(pp - p.emitter_world_pos, p.emitter_tangent));
+  uv *= p.emitter_scale_rcp;
+  uv *= 0.5;
+  uv += 0.5;
+
+  bool in_range = uv.x < 1 && uv.y < 1 && uv.x > 0 && uv.y > 0;
+  [branch]
+  if (!in_range) {
+    return p.color;
+  }
+
+  float4 c = p.emitter_texture.SampleLevel(linear_clamp_s, uv, 0);
+  return lerp(p.color, c.rgb, c.a);
+}
+#endif
+
 struct FogResult {
     float4 color;
     float depth;
@@ -45,7 +85,6 @@ FogResult raymarched_fog(v2f i, FogParams p)
 
   float linearZ =
     GetLinearZFromZDepth_WorksWithMirrors(zDepthFromMap, screen_uv);
-  linearZ = min(1E3, linearZ);
 
   // Get intersection with plane at elevation y.
   float plane_y = p.y_cutoff;
@@ -57,6 +96,7 @@ FogResult raymarched_fog(v2f i, FogParams p)
     }
   }
   linearZ = min(linearZ, distance_to_y);
+  linearZ = min(linearZ, 1200);
   linearZ -= ro_epsilon;
 
   float dither = p.dithering_noise.SampleLevel(point_repeat_s,
@@ -69,7 +109,7 @@ FogResult raymarched_fog(v2f i, FogParams p)
 
   float step_size = linearZ / p.steps;
   float3 pp = ro;
-  float d = 0;
+  float4 color = 0;
   [loop]
   for (uint ii = 0; ii < p.steps; ++ii) {
     pp += step_size * rd;
@@ -97,18 +137,27 @@ FogResult raymarched_fog(v2f i, FogParams p)
     //   y=9 -> density = 1/8
     float exponent = height_clamped / p.height_density_half_life;
     float factor = pow(2, -exponent);
+#if defined(_CUSTOM30_FOG_HEIGHT_DENSITY_MINIMUM)
+    factor = max(factor, p.height_density_minimum);
+#endif
     cur_d *= factor;
 #endif
 
     cur_d = saturate(cur_d);
-    d = d + (1 - d) * cur_d;
+
+#if defined(_RAYMARCHED_FOG_EMITTER_TEXTURE)
+    float4 cur_c = float4(getEmitterData(p, pp) * cur_d, cur_d);
+#else
+    float4 cur_c = float4(p.color * cur_d, cur_d);
+#endif
+    color += (1.0f - color.a) * cur_c;
   }
 
   FogResult r;
-  r.color.rgb = _Raymarched_Fog_Color;
+  r.color = color;
   //r.color.rgb = saturate(log(linearZ) / 5.0);
   //r.color.rgb = float3(screen_uv, 0);
-  r.color.a = d;
+  //r.color.a = d;
   r.depth = 0.0001;  // Very small depth value to render in front
   return r;
 }