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Encapsulation of shader in game engine & problem with PIX in DX SDK


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#1 monkeyboi   Members   -  Reputation: 188

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Posted 09 September 2012 - 09:42 AM

Hi, I have been researching how to encapsulate shader functions in a game engine that could run on diferent platforms with minimum limitation. It seems CG is the best choice among all due to its high portability and easily to be transfered into HLSL or GLSL. Here either GLSL or HLSL is in assembly language which is really inconvenient for programmer to read and debug. So my though is implement interfaces for high level language in the game engine as well. The biggeast benefit is it is more intuitional while using PIX to debug my shader. However I got 2 questions here to be solved:
1. A robust structure of renderer that could compile shaders in both assembly language and high level language
2. Variables setting. In assembly language the variables setting is actually through setting different registers, On contrast in HLSL for example it is through pair of interfaces like GetParameterByName and SetMatrix. Is there any compromised method? Otherwise I have to implement another set of functions that specifically for HLSL,which seems quite clumsy.

I also encounter some problems while I am using PIX to debug my program. I choose the second option to start experient that is a single-frame capture of DIrect3D whenever F12 is pressed. However each time I press F12, PIX will stop working so I include debug output messages and restart experiement. Then I got

Created PIXRun file at: C:\Users\Jerry\AppData\Local\Temp\PIX74D8.tmp
An unhandled exception occurred.
Closing Run File

C:\Users\Jerry\AppData\ is a hiden file. And I don't know how to change this directory. So I reckon the problem is something relevant to permission. Not sure here.

Any help will be appreciated

Many thanks

Jerry

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#2 Hodgman   Moderators   -  Reputation: 27761

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Posted 09 September 2012 - 09:50 AM

In assembly language the variables setting is actually through setting different registers, On contrast in HLSL for example it is through pair of interfaces like GetParameterByName and SetMatrix.

Those 2 functions aren't related to HLSL, they're part of the "Effect framework" (.fx file format), which is a wrapper around HLSL. The Cg equivalent is CgFX.
If you don't use the "Effect framework", then all of your HLSL variables still correspond to specific registers, the same as you're used to with your assembly shaders.

It seems CG is the best choice among all due to its high portability and easily to be transfered into HLSL or GLSL

HLSL and Cg are almost exactly the same, so much so that I write my shaders once, and I compile them as HLSL for D3D and compile the same file as Cg for OpenGL Posted Image

A robust structure of renderer that could compile shaders in both assembly language and high level language

Is this required? Assembly shaders have been phased out in D3D (from DX10 onwards, you have to use HLSL). Anyway, as above in D3D, compiled HLSL shaders act the same as asm shaders.

Edited by Hodgman, 09 September 2012 - 09:51 AM.


#3 monkeyboi   Members   -  Reputation: 188

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Posted 09 September 2012 - 04:51 PM

Hi Hodgman, thanks you so much for the expanation.

So, a compiled shader is the shader in assambly language, isn't it? I use cgc to compile a cg file as HLSL orGLSL, Both of the outputs are in assambly language. And this compilation can be done using D3DXCompileShaderFromFile function in D3D, is this right?

So for setting variables, I can use SetVertexShaderConstantF (SetPixelShaderConstantF) or GetConstantByName and SetFloat (or other pairs). But the later one assumes I compile the shader in my program since I need the constant table to call setting functions?

Is this required? Assembly shaders have been phased out in D3D (from DX10 onwards, you have to use HLSL). Anyway, as above in D3D, compiled HLSL shaders act the same as asm shaders.

.

Because effect frame can involves as many passes as I want. So I am quite interested in how to encapsulate both FX and CGFX in one game engine, especially how to effectively set variables. Any references?

Best regards

Jerry




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