Getting fancy with texture mapping (Part 2) CS559 Spring Apr 2017

Transcription

1 Getting fancy with texture mapping (Part 2) CS559 Spring Apr 2017

2 Review Skyboxes as backdrops Credits : Flipmode 3D

3 Review Reflection maps Credits : NVidia

4 Review Decal textures Credits : andreucabre.com

5 Review Normal maps

6 Two-pass effects

7 Applica'on Program The full fixed-function pipeline (1992) Graphics Driver Command Buffer (Triangle Queue) Vertex Queue Vertex Processing (TCL) Vertex Cache Assembly Triangle Processing Rasterize Pixel Queue Pixel Processing Pixel Tests Vertex shading Geometry Shading Pixel Shading Texture Memory Render to texture Frame Buffer [Baseline] [RTT example]

8 Render-to-texture jsbin.com/quxudovesu/edit Framebuffer objects A destination buffer for offscreen rendering Separate rendering pass per framebuffer (including on-screen) Prior passes available to the shaders (just use the results as textures)

9 Render-to-texture jsbin.com/quxudovesu/edit.js start(){ initshaders(); senddata(); inittextures(); draw() }

10 Render-to-texture jsbin.com/quxudovesu/edit.js start(){ initshaders(); senddata(); inittextures(); draw() }

11 Render-to-texture jsbin.com/quxudovesu/edit.js start(){ initshaders(); senddata(); inittextures(); draw() }

12 Render-to-texture jsbin.com/quxudovesu/edit.js start(){ initshaders(); senddata(); inittextures(); draw() }

13 Render-to-texture jsbin.com/quxudovesu/edit.js start(){ initshaders(); senddata(); inittextures(); draw() }

14 Render-to-texture jsbin.com/quxudovesu/edit.js start(){ initshaders(); senddata(); inittextures(); draw() }

15 Render-to-texture jsbin.com/quxudovesu/edit.js start(){ initshaders(); senddata(); inittextures(); draw() }

16 Render-to-texture jsbin.com/quxudovesu/edit.js start(){ initshaders(); senddata(); inittextures(); draw() }

17 Render-to-texture jsbin.com/quxudovesu/edit.js start(){ initshaders(); senddata(); inittextures(); draw() }

18 Render-to-texture jsbin.com/quxudovesu/edit.js start(){ initshaders(); senddata(); inittextures(); draw() }

19 Render-to-texture jsbin.com/quxudovesu/edit.js start(){ initshaders(); senddata(); inittextures(); draw() }

20 Render-to-texture jsbin.com/quxudovesu/edit.js start(){ initshaders(); senddata(); inittextures(); draw() }

21 Render-to-texture jsbin.com/quxudovesu/edit.js start(){ initshaders(); senddata(); inittextures(); draw() }

22 Render-to-texture jsbin.com/quxudovesu/edit In real use you may have to Use different shaders per pass Use depth buffer Selectively draw objects (and many other adjustments, depending on the algorithm implemented via RTT)

23 Shadow mapping

24 Shadow mapping Why shadows? Enrich lighting Provide significant cues on scene (order, depth )

25 Shadow mapping Intuition: Locations that are lit are visible from the light source s viewpoint

26 Shadow mapping First step: Place camera at light s location Render & store depth image (shadow map)

27 Shadow mapping Second step: Render from camera s position (Per fragment) compare distance to light with shadow map value

28 Shadow mapping Second step: Shadow map value larger -> Fragment shadowed Shadow map value less/equal -> Fragment lit

29 Shadow mapping Issues : Field of view

30 Shadow mapping Issues : Field of view Remedy render 6 shadow maps in a cube

31 Shadow mapping Issues : Z-fighting

32 Shadow mapping Issues : Z-fighting

33 Shadow mapping Issues : Z-fighting Solution : Bias (be careful how much!)

34 Shadow mapping Additional issues: Sampling (resolution of shadow map) Thin objects Multiple light sources Other methods exist (e.g. shadow volumes) (but may require CPU intervention)

35 Dynamic environment maps First pass : Render scene into the 6 faces of the environment cubemap Second pass : Normal environment mapping with rendered texture [Example] [Example]

36 Projector textures Project texture coordinates on scene, to use with secondary texture Need to worry about sampling issues all over again (no direct mipmap help)

37 Ambient occlusion Darken ambient lighting component near folds

38 Ambient occlusion Can be very expensive (and very cool) Screen-space approximation : Uses depth field, estimates occlusion factor