open gl (ebook) shader programming - cgfx opengl 2.0.pdf

8/11/2019 Open Gl (Ebook) Shader Programming - Cgfx Opengl 2.0.pdf

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Shader ProgrammingCgFX, OpenGL 2.0

Michael Haller

2003


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Outline

What is CgFX? CgFX runtime

Production pipeline with CgFX

CgFX Tools set

OpenGL 2.0


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What is CgFX?

CgFX (C for Graphics Effekt File)

Supports Microsoft .fx files Cg plus:

Multi-pass

Hardware fallbacks (techniques)

Complete Hardware states

Tweakables

MS .fx (HLSL) plus:

DirectX8 and OpenGL

MAC and Linux


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CgFX overview


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Game Image

Application (game, renderer, )

Typical Production Pipeline

DCC tool (Maya, Max, Soft Image, )

Digital Content Creation

Scene exporter plug-in

Scene manager

App Scene Managerhard-coded to choose

at run-time

the appropriate ASM

shaders + state

for the hardware

Artists create models,

textures, maps, in

DCC tool of choice

ASMShaders

(HW1)

Programmers

write

assembly for

different

hardware

ASM

Shaders

(HW2)

Not the same!

DCC Image

Models, Textures, Maps,


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DCC tool (Maya, Max, Soft Image, )

Scene exporter plug-in

FX material plug-in

Application (game, renderer, )

FX runtime

Scene manager

CgFX Production Pipeline

For any FX, App SceneManager chooses

at run-time

the appropriate

technique

for the hardware

Artists assign

FX files

to scene objects

and tweak parameters

for each objectin real-time

FX

files

Programmers

and/or artists

wri te FX

effects

Models, Textures, Maps,FX effects + parameters

Same Image


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CgFX Example File - Structure

Global declarations

Tweakable declarations

Vertex shaders

Fragment shaders Techniques to encapsulate shaders


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Techniques

effect myEffectName {technique PixelShaderVersion

{};

technique FixedFunctionVersion{};

technique LowDetailVersion

{};

};


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Passes

Each technique contains one or more passes

Each pass may contain a vertex program, afragment program, or both. E.g.

Pass 0: Fixed-function pixel processing to output the

ambient color. Pass 1: ps_1_1 fragment program Pass 2: ps_2_0 fragment program

Typically, all passes of a technique use Cg or

assembly programs.


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Render States

pass firstPass {

DepthWriteEnable = true;

AlphaBlendEnable = false;MinFilter[ 0 ] = Linear;

MagFilter[ 0 ] = Linear;

MipFilter[ 0 ] = Linear;

// Pixel shader written in assembly

PixelShader = asm {

ps.1.1

tex t0;

mov r0, t0;

};

};


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Variables and Semantics

Global and per-technique Cg-style variables(passed as uniform parameters):

These variables can contain a user-definedsemantic, which helps applications provide the

correct data to the shader:

bool AlphaBlending = false;

float bumpHeight = 0.5f;

float4x4 myViewMatrix : ViewMatrix;

texture2D someTexture : DiffuseMap;


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Annotations

Additionally, each variable can have an optional annotation.

An annotation describes a user interface element formanipulating uniform variables:

float bumpHeight

= 0.5f;


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My first fx example (Blinn)

struct appdata {

float4 vPosition : POSITION;

float4 vNormal : NORMAL;

float4 vTexCoords : TEXCOORD0;

};

struct vpconn {

float4 vTexCoord0 : TEXCOORD0;

float4 vDiffuse : COLOR0;float4 vPosition : POSITION;

float4 vSpecular : COLOR1;

};


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My first fx example (Blinn) II

// un-tweakables

float4x4 worldView : WorldView;

float4x4 worldViewIT: WorldViewIT;

float4x4 worldViewProjection : WorldViewProjection;

[...]

// tweakables

float4 diffuse : DIFFUSE

= { 0.1f, 0.1f, 0.5f, 1.0f };

[...]

float4 lightPos : Position

= {100.0f, 100.0f, 100.0f, 0.0f};


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My first fx example (Blinn) III

vpconn vs_blinnShading(appdata IN,

uniform float4x4 ModelViewProj,

uniform float4x4 ModelView,uniform float4x4 ModelViewIT,

uniform float4x4 ViewIT,

uniform float4x4 View,

uniform float4 lightPos,

uniform float4 diffuse,uniform float4 specular,

uniform float4 ambient) {

vpconn OUT;

[]

OUT.vDiffuse = diff_term;

OUT.vPosition = mul(ModelViewProj,IN.vPosition);

return OUT;

}


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My first fx example (Blinn) IV

technique Blinn {

pass p0 {

Zenable = true;

ZWriteEnable = true;

CullMode = None;

VertexShader = compile vs_1_1 vs_blinnShading(

worldViewProjection, worldView,

worldViewIT, viewIT, view,

lightPos, diffuse,

specular, ambient);

}

}


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Results (Blinn) I


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Results (Blinn) II


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Production Pipeline with CgFX


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CgFX Tools Set

Integrated authoring in DCC apps:

3ds MAX 5.1

MAYA 4.5

XSI (CgFX Coming soon...) NVB Exporter

CgFX Viewer

OpenGL ARB, DirectX8, DirectX9


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3D Studio Max 5.1

stdmaterial CgFX

Ability to select MAX scene lights and connect them to.fx parameters

On the fly editing of shaders and auto-update of .fxGUI

MAXSCRIPT support

Source Code


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Integration in 3D Studio Max


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CgFX Viewport

Manager

Intuitive artist

controls(sliders, color pickers, etc.)

Supports .fxfile format

Multiple

Techniques

for fallbacks

Dynamic, shader-

specific GUI


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Customizable Parameters are

specific to each effectBitmaps can be

swapped

Color and numericvalues can be

changed

Shader

changed by

selecting anew fx file


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NVB Exporter for 3ds max

Based on Pierre Terdimans 3ds max exporter

http://www.codercorner.com/Flexporter.htm Exports Scene data

Mesh, materials, lights, camera, skinning, etc...

Exports CgFX materials ICgFXDataBridge interface

Source code


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CgFX Viewer

Scene graph GUI

.fx parameters edition Error reporting for easy

.fx

file problemidentification

Runs OpenGL, DirectX8,DirectX9

Switch between devices

at any point


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The CgFX Viewer can be used as a production resource

and a code example for implementing CgFX

Main Application

Window

Connection

Editor

Window

CgFX Viewer II


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How Does CgFX relate to Cg?

CgFX describes an entire effect Cg

implements a particular function required byan effect

CgFX describes all the parameters (and their

meaning or semantics) that the app has toprovide automatic parameter discovery

CgFX can describe complex multi-pass effects

CgFX can handle multiple techniques


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Hardware Shader Workflow

Designing Shaders and

Using Existing Shaders

Artist-Configurable

Parameters

Editing Shader

Parameters

Exporting Shader

Parameters to Game

Engine


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Small Efficient Shaders

Multiple, narrowly-targeted shaders are more

efficient/faster than large all-purpose shaders

Several

shaders may

share similarfeatures and

lighting

models


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OpenGL: Where do you want to go today?


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OpenGL 2.0 Goals

Reduce the need for existing and future

extensions to OpenGL by replacing complexitywith programmability.

Backward compatibility to OpenGL 1.x

Address the needs of dynamic mediaauthoring and playback applications neededby OpenML.


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Status of Shading Language

Extensions to support the OpenGL Shading Language

Language approved as ARB extensions in June 2003

Language and extensions expected to be rolled intoOpenGL in 6 rolled into OpenGL in 6-12 months 12

months That version of OpenGL will be called OpenGL 2.0 It will still be backwards compatible with 1.0-1.5

3Dlabs is shipping a preliminary implementation


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Overview

h k !


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hanks!

open gl (ebook) shader programming - cgfx opengl 2.0.pdf

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