图形学笔记 -- 高级 D3D10 着色器创作

偶然发现 D3D10 对频谱可视化支持的很好。惊讶。

HLSL10 Workshop.ppt Advanced D3D10 Shader Authoring

Overview

• Review of Direct3D 10 and HLSL 4.0
• The power of the programmable pipeline
• Guided exercises: Visualizer

Some New D3D10 Features

• Completely re-architected from D3D9 for configurability and performance
• Geometry Shader
• Fixed-function lighting and transformation now programmable in HLSL 4.0
• Configurable pipeline
  • Flexible shader signatures
  • System-generated values

High Level Shader Language

• HLSL is a highly effective language for writing shaders
• Syntax is similar to ‘C’
  • Preprocessor defines (#define, #ifdef, etc)
  • Basic types (float, int, uint, bool, etc)
  • Operators, variables, functions
• Has some important differences
  • Builtin variables (float4, matrix, etc)
  • Intrinsic functions (mul, normalize, etc)

Overview of the Pipeline

Vertex Shader 4.0

• Input
  • Vertices
  • Shader Constants
  • System Variables ( VertexID )
• Output
  • It’s up to you now
  • Color, Texture Coordinates, etc

System-generated Values

• Values usable in shaders generated by the D3D10 runtime
• Act exactly like semantics, just tag your variable and off you go
• SV_VertexID
  • Provided to the VS
• SV_InstanceID
  • Provided to the VS
• SV_PrimitiveID
  • Provided to the GS (or PS if there is no GS)

Geometry Shader 4.0

• Input
  • Per-primitive data (3 verts for a tri)
  • System variables ( PrimitiveID )
• Output
  • Points, lines, triangles
  • Render target index, clip distances
  • Stream data to a buffer on the GPU
    • aka stream out

Geometry Shader Restrictions

• Cannot output more than 4096 bytes of information for each input primitive
  • Performance is not guaranteed when amplifying at this level

Pixel Shader 4.0

• Input
  • Interpolated data from vertex shader
• Output
  • Pixel color (with alpha)
  • Optional: depth

What This Means: Configurability

• The real power of Direct3D 10 is that there are many ways to accomplish any one task
• More and more tasks can be pushed onto the GPU
• Performance/quality tradeoff can be made on your terms

Guided Exercises: Visualizer

• DirectX 10 - exploitive effects in an audio visualizer
• Roughly based on the GPUSpectrogram sample in available in the DirectX SDK
• A framework to try out HLSL 4.0 plus to show:
  • InstanceIDs
  • Integer offset samplers
  • Geometry amplification
• Debugging using PIX

Guided Exercises - General Directions

• Each effect file guides you through the exercises.
• Breakdancin’ Bob shows up in the comments where there is something to learn or something to do.
• Use Visual Studio to edit the effect and cpp files and to build.
• If you get stuck or need help, raise your hand. A proctor will assist you.

The Basic Idea

• GPUSpectrogram uses the GPU to analyze the raw audio data and evaluate the levels of various frequency ranges

• To check this code out and see the new integer instruction set in action, check out the GPUSpectrogram sample or GPUSpectrogram.fx included in the workshop

Using Spectrogram Data

• We’ll be using shaders to take this data and make a visualizer
  • Dancing bars with extra effects
• These techniques directly apply to game scenarios
  • The configurability of the pipeline makes the possibilities endless

Exercise 1: Drawing the Bars

• Please open Exercise01.sln
• Hint: Bob’s hiding in Exercise01.fx
• Solution:

input.Pos.y *= abs(spectrogram.r)*fScale*g_fScale;

Exercise 2: Performance

We’ll be using PIX to do performance analysis

1. Build Exercise02.sln
2. Open PIX (Start->PIX for Windows)
3. File -> New Experiment
4. Navigate to your built exercise
5. Select “A replayable Direct3D call stream, saved to file:”
6. Enter a file name ending in “.PIXrun”
7. Click “Start Experiment”

• When you exit the application, you’ll have a log of every D3D command that was executed
• We’ve created a perf event called “Draw Bars” that will help you find the actual draw calls for the bars.
• There is a small problem in how it’s rendering that’s causing a loss in performance…
• You might want to look in Exercise02.cpp
• Solution:

pd3dDevice->DrawIndexedInstanced( (UINT)pSubset->IndexCount, g_iNumInstances, 0, (UINT)pSubset->VertexStart, 0 );

Exercise 2: Debugging

Exercise 3: Geometry Amplification

• Please open Exercise3.sln
• Hint: Bob’s hiding in Exercise3.fx
• Solution:

TriStream.Append( output );

Exercise 4: More Performance

• We’ll be using PIX to see how we can tweak rendering parameters to maximize performance
• We’ve made a custom set of variables you can track in PIX so you can see the values of the sliders
• We’ll be seeing how changing these values changes framerate

1. Build Exercise04.sln
2. Open PIX (Start->PIX for Windows)
3. File -> New Experiment
4. Navigate to your built exercise
5. Click “More Options”
6. For CounterSet, select “(Custom)”
7. Add all counters under the “Pluging Counters”
8. Click “OK”
9. Click “Start Experiment”

Exercise 4: More Debugging

• You can assign colored lines to each of the slider values along the bottom of the chat
• You can also set the framerate as a graphed line
• You can see the framerate has a direct correlation to many of these sliders (some more than others)

Exercise 5: Floor Effect

• Please open Exercise05.sln
• Hint: Bob’s hiding in Exercise05.fx
• Solution:

tex.x += sin( input.Tex.y*40 )*0.001;
tex.y += sin( input.Tex.y*60 )*0.001;

Exercise 6: Screen Effects

• Please open Exercise06.sln
• Hint: Bob’s hiding in Exercise06.fx

• Solution (One of many!):

float2 tex = input.Tex.xy*2 - 1;
float texMag = length( tex );
tex /= texMag;
float shift = sin(texMag*50.0-g_fTime*3)*g_fElapsedTime*0.3;
float2 offset = float2(tex.y*shift, -tex.x*shift );
tex *= texMag;
tex += offset;
tex = tex/2 + 0.5;
float4 color = BoxFilter( g_samLinearClamp, tex, 3 );
return color * 0.80;

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