Virtual Camera 1 Real-Time Rendering

Transcription

1 02501 E10 Virtual Camera 1 Real-Time Rendering J. Andreas Bærentzen

2 A Really Short History of Real-Time Graphics PerformerTown Doom Second Life

3 State of the Art CryEngine 3

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5 Hvad sker i et grafikkort? hjørner trekant rasteriseret interpolerede farver Vertex programmer: belysning og transformation Samling af primitiver Primitiv programmer Rasterisering Pixel shadere: texture mapping interpolation af farver

6 Bare lige for at illustrere...

7 Betydningen af texturer Her kigger I på ca. 5 polygoner

8 Små revolutioner i grafikkort-land 1. Fra en dum framebuffer til en lynhurtig maskine til at tegne trekanter med tekstur. 2. Fra en konfigurerbar til en programmerbar trekantsmaskine. halvfemserne til ca Fra en maskine der processerer til en maskine der skaber. lige nu

9 State of the Art: NVIDIA GTX 295 Two G200b GPUs (2x1400 million transistors) Process: 55 nm Clocks (MHz): 576 (core), 1242 (shader), 2000 (mem) 480 Scalar Shader Processors. Memory: 2 x 896 MB 224 GB/s memory bandwidth. 92.2/32.2 billion texels/pixels per second. DirectX 10.1 (OpenGL 2.1?!)

10 State of the Art: NVIDIA GTX 295 Two G200b GPUs (2x1400 million transistors) Process: 55 nm Clocks (MHz): 576 (core), 1242 (shader), 2000 (mem) 480 Scalar Shader Processors. Memory: 2 x 896 MB Outdated 224 GB/s memory bandwidth. 92.2/32.2 billion texels/pixels per second. DirectX 10.1 (OpenGL 2.1?!)

11 State of the Art: NVIDIA GTX 480 Single chip: 3 Billion processors Process: 40 nm Clocks (MHz): 700 (core), 1401 (shader), 3696 (mem) 480 Scalar Shader Processors. Memory: 1536 MB GB/s memory bandwidth. 42/33.6 billion texels/pixels per second. DirectX 11 (OpenGL 4.1)

12 The geometry part of the pipeline Object World Eye Model View Projection Clip W divide Normalized device Viewport Window

13 Modelling Transformat ions All modelling transformations are composed of translation, rotation, and scaling. T = Order does matter t x t y t z R = R S = s x s y s z aling factors along each a

14 Transformation Order SRT RST TSR It is possible, even easy to create a hierarchical object by combining transformations

15 View Transform Computing the view transform: V = c x x c x y c x z 0 c y x c y y c y z 0 c z x c z y c z z e x e y e z OpenGL API there is only a single modelview t

16 Projection Types orthogonal perspective oblique rarely used

17 What does Perspective do? X (1,1) α Z (-1,-1) P = A cot α cot α n+f 0 0 n f nf n f

18 Linear Interpolation p 0 p 0 q q p 1 p 2 p 1 p 2 [b 0,b 1,b 2 ] T = 1 A(p 0, p 1, p 2 ) [A(q, p 1, p 2 ),A(p 0, q, p 2 ),A(p 0, p 1, q)] T f q = b 0 f 0 + b 1 f 1 + b 2 f 2

19 Perspective Correct Interpolation This is what happens if we simply use linear interpolation f q = b 0 f 0 + b 1 f 1 + b 2 f 2

20 Perspective Correct Interpolation This is what happens if we use perspective correct linear interpolation f q = b 0 f 0 f w 0 + b 1 f 1 w 1 + b 2 2 w b 0 w 0 + b 1 w 1 + b 2 w 2

21 Depth Buffering Depth fighting The result of switching depth buffering off

22 X Shading h Z Local light contributions L a = k a I a ght L d in = the k d cos(θ)i en d = k d (n l)i d L s = k s (h n) p I s where h = v + l v + l s, alternative, d Putting it all together L = L a + L d + L s = k a I a + k d (n l)i d + k s (h n) p I s

23 Programmable Shading DEMO