Ready for review

[shrekshao]

@pjcozzi @likangning93

• Finished the core features. Still need to add texture shading, do clean up, and write INSTRUCTION.md. and get a working gltf sponza
• Basic work flow
  • optional depth prepass
  • lightCulling, write the tileLight buffer. threads in a tile share a light array, each element indicating if light[idx] overlap with current tile. Each thread handles one light.
  • lightAccumulation, naive Forward with testing light visible or not
• Students will focus on writing shaders doing light culling and accumulation. Once they fully understand the content and how webgl works (this might take longer than writing code), the workload should be pretty light. Main files for the assignment (one you want to review):
  • glsl/lightCulling.frag.glsl
  • glsl/lightAccumulation.frag.glsl
  • glsl/tileLightDebug.frag.glsl
  • glsl/forward.frag.glsl (this is naive forward pipeline, can be used as a warmup for glsl)
• The tile based Forward+ currently has a improvement about 5 fps with 220 lights compared to Forward shading (still use a texture to read light info) in the duck scene.
• With tile min max depth culling, it performances worse. This doesn't go as expected.
• Extra credit ideas:
  • better frsutum culling method http://www.iquilezles.org/www/articles/frustumcorrect/frustumcorrect.htm
  • fully utilize the tileLightsTexture rgba channel to allow more lights in a scene
  • better idea to parallelize threads
  • performance analysis
  • num of lights
  • tile size
  • with/without frustum near far dpeth/tile min max depth culling
  • use profiler to find bottleneck functions
  • compared to forward shading
  • compared to deferred shading (students pair with those choosing a different one. Although not a complete fair comparison)

I think it's totally reasonable to discard this one if shipping the content in lecture is difficult. And also time is quite limited now. I can save it for myself and next year.

[shrekshao]

FYI, a performance comparison. Very coarse, not strictly controlling variables (e.g. deferred had a different setup for passing light info and quite a lot optimization, scene and camera are not exactly the same) .

• num of lights = 120
• light radius = 4.0
• sponza model

shader	FPS
forward	13
forward plus	23
forward plus with depth culling	17
deferred	5
deferred with scissor	33
deferred with sphere proxy	45

[shrekshao]

INSTRUCTION.md ready for review. Delete implementation for assignment ready.