Real-Time Shading Using Programmable Graphics Hardware

Introduction, Setup and Examples

Wan-Chun MaNational Taiwan University

Course Infomation Instructor

Wan-Chun Ma, Alex Dept. of Computer Science and Information Engineering, Nati

onal Taiwan University http://graphics.csie.ntu.edu.tw/~firebird

Course 4/28, 5/5, 5/12, 5/14 Suggested readings

R. Fernando and M. J. Kilgard. The Cg Tutorial: The Definitive Guide to Programmable Real-Time Graphics, Addison-Wesley, 2003 (beginners only!)

R. J. Rost. OpenGL Shading Language, Addison-Wesley, 2004 http://graphics.csie.ntu.edu.tw/~firebird/dokuwiki/doku.php?

id=tech:courses:dci_rts:home

The Student... The student should be familiar with

C/C++ programmingGraphics basics

Transformations in 3D (translation, rotation, modelview, projection)

Rasterization Texturing

OpenGL GLUT, GLUI Use texturing in OpenGL

Today’s Schedule Introduction Setup of Programming Environment Real-Time Shading Examples

Introduction

Evolution of GPUs

Virtual FighterSEGA

Dead or Alive 3Temco

Dawn DemoNVIDIA

NV1 Xbox (NV2A) GeForce FX (NV30)

50K triangles/sec1M pixel ops/sec1M transistors

100M triangles/sec1G pixel ops/sec20M transistors

200M triangles/sec2G pixel ops/sec120M transistors

1995 2001 2003

The 5 Generations of GPU 1st generation (up to 1998)

NVIDIA TNT2, ATI Rage, 3dfx Voodoo3 Lack of transform vertices of 3D objects. Vertex

transformation are done by CPU Limited math operations for combining textures to

compute the color of pixels

2nd generation (1999-2000) NVIDIA GeForce 256, GeForce 2, ATI Radeon 7500 GPU has the ability to do transformation and lighting. Bot

h OpenGL and DirectX 7 support vertex transformation by hardware

Configurable (in driver level) but not programmable

The 5 Generations of GPU 3rd generation (2001)

NVIDIA GeForce 3, GeForce 4 Ti, Xbox, ATI Radeon 8500 Vertex programmability: DirectX 8 vertex shader and OpenG

L ARB vertex program Pixel-level configurable

4th generation (2002) NVIDIA GeForce FX, ATI Radeon 9700 Vertex and pixel programmability High-level shading language (NVIDIA Cg, Microsoft HLSL, Ope

nGL GLSL)

5th generation (2004) NVIDIA GeForce 6, ATI Radeon X Infinite length shader program Dynamic flow control

GPU Model (Old) Fixed function pipeline

GPU Model (Current) Programmability!

GPU Process

VertexProcessin

g

FragmentProcessing

Programming GPU However, programming in assembly

is painfulDP3 R0, c[11].xyzx, c[11].xyzx;RSQ R0, R0.x;MUL R0, R0.x, c[11].xyzx;MOV R1, c[3];MUL R1, R1.x, c[0].xyzx;DP3 R2, R1.xyzx, R1.xyzx;RSQ R2, R2.x;MUL R1, R2.x, R1.xyzx;ADD R2, R0.xyzx, R1.xyzx;DP3 R3, R2.xyzx, R2.xyzx;RSQ R3, R3.x;MUL R2, R3.x, R2.xyzx;DP3 R2, R1.xyzx, R2.xyzx;MAX R2, c[3].z, R2.x;MOV R2.z, c[3].y;MOV R2.w, c[3].y;LIT R2, R2;

DX8 shader instructions Basic: mov, add, mul, mad, rsq… Vector operation: dp3, dp4… Miscellaneous: lit, exp, log, min, max, te

x…

Oh my god!

Programming GPU The need of high level shading

languageCompile

DP3 R0, c[11].xyzx, c[11].xyzx;RSQ R0, R0.x;MUL R0, R0.x, c[11].xyzx;MOV R1, c[3];MUL R1, R1.x, c[0].xyzx;DP3 R2, R1.xyzx, R1.xyzx;RSQ R2, R2.x;MUL R1, R2.x, R1.xyzx;ADD R2, R0.xyzx, R1.xyzx;DP3 R3, R2.xyzx, R2.xyzx;RSQ R3, R3.x;MUL R2, R3.x, R2.xyzx;DP3 R2, R1.xyzx, R2.xyzx;MAX R2, c[3].z, R2.x;MOV R2.z, c[3].y;MOV R2.w, c[3].y;LIT R2, R2;

// A Phong model shaderCOLOR c = k_a + k_d * dot(N, L) + k_s * pow(max(0, dot(N, H)), k_exp);

High level shading language Easier to read and modify Cross-platform Code reuse

Cg: A Shading Language Cg is a high level language from NVIDIA for pro

gramming GPUs, developed in close collaboration with Microsoft

Cg stands for “C for Graphics”

Cg enables a dramatic productivity increase for graphics development developers of: Games CAD tools Scientific visualizations

Cg: A C-like Language Syntax, operators, functions from C Conditionals and flow control (for, if) Particularly suitable for GPUs:

Express data flow of pipeline/stream architecture of GPUs (e.g. vertex-to-pixel)

Vector and matrix operations Support hardware data types for maximum performance Exposes GPU functions for convenience and speed:

Intrinsic: (mul, dot, sqrt, exp, pow) Built-in: extremely useful and GPU optimized math, utility and g

eometric functions (noise, ddx, ddy, reflect) Compiler uses hardware profiles to subset Cg as requi

red for particular hardware feature sets

Cg Workflow Architecture

Cg WorkflowShader Development Application

Cg program source code

// Diffuse lightingfloat d = dot(normalize(N), normalize(L));if (d < 0) d = 0;c = d*tex2D(texture, T)*diffuse;

1. Load/bind program

2. Specify program parameter

3. Specify vertex inputs

4. Render

Cg Compiler

Shader program assembly code

DP3 r0.x, f[TEX0], f[TEX0];RSQ r0.x, r0.x;MUL r0, r0.x, f[TEX0];DP3 r1.x, f[TEX1], f[TEX1];RSQ r1.x, r1.x;MUL r1, r1.x, f[TEX1];DP3 r0, r0, r1;MAX r0.x, r0.x, 1.0;MUL r0, r0.x, DIFFUSE;TEX r1, f[TEX1], 0, 2D;MUL r0, r0, r1;

Shader Compiler

Shader binary0000h: 54 68 69 73 20 69 73 20 65 2D 54 65 58 2C 20 560010h: 65 72 73 69 6F 6E 20 33 2E 31 34 31 35 39 32 2D0020h: 32 2E 31 20 28 4D 69 4B 54 65 58 20 32 2E 34 290030h: 20 28 70 72 65 6C 6F 61 64 65 64 20 66 6F 72 6D0040h: 61 74 3D 6C 61 74 65 78 20 32 30 30 34 2E 36 2E

What Cg can do? Real-time visual effects

What Cg can do? Lots of effects…

Coffee Break Next section: Setup of Programming

Environment

Setup of Programming Environment

Requirement Hardware

The computer should be equipped with programmable graphics hardware

NVIDIA FX, NVIDIA 6, ATI 9x00, ATI X series

SoftwareMicrosoft Visual Studio .NET 2003GLUT, GLUI...

Installation Cg Toolkit 1.3 (10MB)

http://developer.nvidia.com/object/cg_toolkit.html

Check the “Cg Installer for Windows”

NVIDIA SDK 9.0 (340MB, not required) http://developer.nvidia.com/object/sdk_home.ht

ml

FX Composer 1.6 (60MB, not required) http://developer.nvidia.com/object/fx_composer_

home.html Check the “FX Composer 1.6 Installer”

Installation If default installation locations are

used, all the packages are installed in the folder of C:\Program Files\NVIDIA Corporation\

C:\Program Files\NVIDIA Corporation\Cg\NVIDIA FX Composer\SDK 9.0\

My Stuff Several useful codes I collect

http://graphics.csie.ntu.edu.tw/~firebird/download/dci_rts/class.zip

Download it and unpack it into a folder, sayD:\My Projects\Class\Any folder is ok, but remember where

you put it

VC++ Directories Execute visual studio

Tools, Options, Projects, VC++ DirectoriesShow the directories for: Include files

D:\My Project\Class (remember My Stuff?) C:\Program Files\NVIDIA Corporation\Cg\include

Library files C:\Program Files\NVIDIA Corporation\Cg\lib

Ready to Go A small engine

http://graphics.csie.ntu.edu.tw/~firebird/download/dci_rts/env.zip

I will use this engine for shader development during these courses

The first examplehttp://graphics.csie.ntu.edu.tw/~firebird/do

wnload/dci_rts/ex01.zip

Compilation cgc –profile profiles filename

profiles: graphics hardware profiles Vertex: arbvp1, vp20, vp30, vp40... Fragment: arbfp1, fp20, fp30, fp40...

filename: filename of the shader

Examplescgc –profile vp30 test_vtx.cxxcgc –profile fp30 test_frg.cxx

Debugging Debugging is very hard (it is GPU, not

CPU) However, you may still use

intermediate visualization to debug your programOutput intermediate data (e.g. position,

normal, textures…) as color

Coffee Break Next section: Real-time Shading

Examples

Real-Time Shading Examples

Progression Games push hardware, hardware

advances games

Effects in Games

Shadows

Level of detail

Reflection

Shading

Smoke

Effects in Games

Bump mapping

Light mapping

Per-pixel lighting

Multi-texturing

Multi-pass Rendering The rendering pass is not fixed

anymore. A single rendering pass may consists of many functional programs

Multi-pass Rendering Each different program (effect) is

handled individually, and finally summed up to become rendering result

Cg Samples Check out the effect samples in

NVIDIA SDK Browser

The First Cg Example A Phong model shader with color textur

e

ShadersVertex: ex1_vtx.cxxFragment: ex1_frg.cxx

TextureDiffuse: wood.bmp

Vertex Shader

struct v2f{float4 P2D : POSITION; // projected 2D positionfloat4 C : COLOR0; // colorfloat4 T : TEXCOORD0; // texture coordfloat3 P3D : TEXCOORD1; // vertex 3D positionfloat3 N : TEXCOORD2; // normalfloat3 G : TEXCOORD3; // tangentfloat3 B : TEXCOORD4; // binormal};

Vertex-to-fragment data structure

Vertex Shader Main (application-to-vertex)

argumentsv2f main(float4 C : COLOR,float4 P : POSITION,float4 N : NORMAL,float4 T : TEXCOORD0,uniform float4x4 ModelViewProj,uniform float4x4 ModelView,uniform float4x4 ModelViewIT)

Vertex Shader Main body

{v2f OUT;OUT.P2D = mul(ModelViewProj, P);OUT.P3D = P.xyz;OUT.T = T;OUT.N = normalize(N.xyz); // normalOUT.G = normalize(2.0*C.xyz - 1.0); // tangentOUT.B = normalize(cross(OUT.G, OUT.N));return OUT;}

Fragment Shader Fragment-to-screen data structure

struct f2s{float4 C : COLOR0;};

Fragment Shader Main (vertex-to-fragment) arguments

f2s main(v2f IN,uniform sampler2D tex01, // texture 01uniform float3 L,uniform float3 V)

Fragment Shader Main body

{f2s OUT; OUT.rgb = 0;L = normalize(L); V = normalize(V);float3 H = normalize(L+V);float diff = dot(normalize(IN.N), L);if(diff > 0){

float spec = 2*pow(dot(IN.N, H), 128);OUT.C.rgb = diff*tex2D(tex01, IN.T.xy) + spec;

}return OUT;}

Result

Try This... Output red color for all fragments

{f2s OUT; OUT.rgb = 0;// L = normalize(L); V = normalize(V);// float3 H = normalize(L+V);// float diff = dot(normalize(IN.N), L);// if(diff > 0)// {

// float spec = 2*pow(dot(IN.N, H), 128);OUT.C.rgb = float3(1.0, 0.0, 0.0);

// }return OUT;}

Try This... Visualize normal vectors

{f2s OUT; OUT.rgb = 0;// L = normalize(L); V = normalize(V);// float3 H = normalize(L+V);// float diff = dot(normalize(IN.N), L);// if(diff > 0)// {

// float spec = 2*pow(dot(IN.N, H), 128);OUT.C.rgb = (IN.N+1)/2;

// }return OUT;}

End