3 files changed, 106 insertions, 0 deletions

diff --git a/doc/lighting.md b/doc/lighting.md
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+# Lighting
+
+## Forward
+
+```
+for each triangle:
+    for each pixel:
+        for each light:
+            shade(pixel, light)
+```
+
+- Overdraw penalty.
+- Client must specify all lights (for the object) up front.
+
+## Deferred
+
+### Forward Pass
+
+The forward pass generates:
+- Depth
+- Texture ID
+- Texture coordinates
+
+Sampling of textures is deferred to avoid overdraw penalty.
+
+### Pixel-centric Shading
+
+```
+for each pixel:
+    for each light:
+        shade(pixel, light)
+```
+
+- Need a pixel-in-volume test.
+- Inefficient if most pixels are not affected by a light.
+  - Ok:  ambient, directional.
+  - Bad: point, area.
+
+### Light-centric Shading
+
+```
+for each light:
+    volume <- project light volume
+    for each pixel in volume:
+        shade(pixel, light)
+```
+
+- Need to project the light volume.
+- Shades only the pixels that are covered by the volume.
+- For ambient and directional, the volume is all space.
+
+## Clustered
+
+### Cluster Generation
+
+```
+for each light:
+    volume <- project light volume to NDC
+    for each cluster:
+        test(cluster, volume)
+```
+
+- Need a volume-AABB test (the cluster is an AABB in NDC space.)
+- Lighting then proceeds as in deferred.
diff --git a/doc/pipeline.txt b/doc/pipeline.txt
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+@startuml
+:G-buffer;
+fork
+  :Depth;
+fork again
+  :Normal;
+fork again
+  :Tex coords;
+fork again
+  :Tex ID;
+end fork
+:Lighting;
+:Tone map;
+:Gamma correct;
+@enduml
diff --git a/doc/triangle-pipeline.txt b/doc/triangle-pipeline.txt
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+++ b/doc/triangle-pipeline.txt
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+@startuml
+:Triangles;
+:Vertices;
+if (Vertex cache?) then (hit)
+  :Load vertex;
+else (miss)
+  :Transform & Store vertex;
+endif
+:Transformed triangle (clip space);
+:Clip;
+:2D triangles;
+:Backface cull;
+:Rasterize;
+:Pixels;
+if (Depth test?) then (pass)
+  if (Alpha mask?) then (opaque)
+    :Write pixel;
+  else (transparent)
+    :Discard;
+    stop
+  endif
+else (fail)
+  :Discard;
+  stop
+endif
+stop
+@enduml