Comments on: Compiling HLSL into GLSL in 2010 http://aras-p.info/blog/2010/05/21/compiling-hlsl-into-glsl-in-2010/ Random thoughts of a triangle pusher Thu, 09 Feb 2012 07:56:51 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Lettiq http://aras-p.info/blog/2010/05/21/compiling-hlsl-into-glsl-in-2010/comment-page-1/#comment-33307 Lettiq Tue, 08 Jun 2010 22:44:39 +0000 http://aras-p.info/blog/?p=523#comment-33307 I was able to do exactly what you're trying to achieve. For my home project I have a number of cookers, each of them for a single platform (similar to yours, except I prefer GLSL over ARB). During a processing time (can be offline) the cooker loads a HLSL shader using Cg, process it and submit to a library that saves shaders in a unified file taking care of endianess and stuff. I've been using FX file format for my shaders, mostly as it is simple to manage and good enough to convert to various platforms (using given API or Cg). So, the GLSL cooker uses cgCreateEffectFromFile then iterates thru its techniques, passes and parameters getting all the important data to speed up loading time and finally get the shaders code using cgGetProgramString. The GLSL code looks a little weird but it works. However I am still fighting with getting vertex attributes instead of gl_Vertex & Co. Drop me an email if need more details. Cheers! I was able to do exactly what you’re trying to achieve. For my home project I have a number of cookers, each of them for a single platform (similar to yours, except I prefer GLSL over ARB). During a processing time (can be offline) the cooker loads a HLSL shader using Cg, process it and submit to a library that saves shaders in a unified file taking care of endianess and stuff. I’ve been using FX file format for my shaders, mostly as it is simple to manage and good enough to convert to various platforms (using given API or Cg). So, the GLSL cooker uses cgCreateEffectFromFile then iterates thru its techniques, passes and parameters getting all the important data to speed up loading time and finally get the shaders code using cgGetProgramString. The GLSL code looks a little weird but it works. However I am still fighting with getting vertex attributes instead of gl_Vertex & Co. Drop me an email if need more details. Cheers!

]]> By: Aras Pranckevičius http://aras-p.info/blog/2010/05/21/compiling-hlsl-into-glsl-in-2010/comment-page-1/#comment-32429 Aras Pranckevičius Tue, 25 May 2010 11:38:51 +0000 http://aras-p.info/blog/?p=523#comment-32429 @Dimi: because GLSL sucks? :) Seriously though, if we put mobile platforms aside, here's what we use in Unity in 2010: * Windows: D3D9 (assembly shaders, compiled from HLSL) * Mac: OpenGL (ARB assembly shaders, compiled from Cg) * Xbox 360: HLSL is the only option * PlayStation 3: Cg is the only option See? None of the platforms, <em>except</em> mobile platforms with OpenGL ES 2.0 use GLSL. If GLES2.0 would have another option for shaders, we'd gladly use it. Why we aren't using GLSL on OpenGL (Mac)? Because for a very long time, it was unstable as jello. Mysterious bugs in GLSL parser/optimizer, unpredictable runtime behavior, etc. There's just a lot less hidden pitfalls when using ARB assembly shaders. <em>Maybe</em> for Unity 3.0 we'll switch to GLSL on Mac by default, but that is still up in the air. @Dimi: because GLSL sucks? :)

Seriously though, if we put mobile platforms aside, here’s what we use in Unity in 2010:
* Windows: D3D9 (assembly shaders, compiled from HLSL)
* Mac: OpenGL (ARB assembly shaders, compiled from Cg)
* Xbox 360: HLSL is the only option
* PlayStation 3: Cg is the only option

See? None of the platforms, except mobile platforms with OpenGL ES 2.0 use GLSL. If GLES2.0 would have another option for shaders, we’d gladly use it.

Why we aren’t using GLSL on OpenGL (Mac)? Because for a very long time, it was unstable as jello. Mysterious bugs in GLSL parser/optimizer, unpredictable runtime behavior, etc. There’s just a lot less hidden pitfalls when using ARB assembly shaders. Maybe for Unity 3.0 we’ll switch to GLSL on Mac by default, but that is still up in the air.

]]> By: Dimi http://aras-p.info/blog/2010/05/21/compiling-hlsl-into-glsl-in-2010/comment-page-1/#comment-32426 Dimi Tue, 25 May 2010 10:14:44 +0000 http://aras-p.info/blog/?p=523#comment-32426 I dont understand why an engine like Unity with roots in the Mac/OS should use HLSL at all. Why not use GLSL for everything and port to HLSL only for XBox. I dont understand why an engine like Unity with roots in the Mac/OS should use HLSL at all.
Why not use GLSL for everything and port to HLSL only for XBox.

]]> By: n00body http://aras-p.info/blog/2010/05/21/compiling-hlsl-into-glsl-in-2010/comment-page-1/#comment-32392 n00body Mon, 24 May 2010 20:09:10 +0000 http://aras-p.info/blog/?p=523#comment-32392 No, right now I am doing the compilation at runtime. Currently, I am writing my own renderer so I can experiment with various rendering techniques to test their merit. Since my focus is deferred rendering, I don't have a lot of shader combinations. So shader compilation at runtime hasn't really been an issue thus far. Ultimately, I guess my suggestion isn't applicable to your situation. No, right now I am doing the compilation at runtime. Currently, I am writing my own renderer so I can experiment with various rendering techniques to test their merit. Since my focus is deferred rendering, I don’t have a lot of shader combinations. So shader compilation at runtime hasn’t really been an issue thus far.

Ultimately, I guess my suggestion isn’t applicable to your situation.

]]> By: Aras Pranckevičius http://aras-p.info/blog/2010/05/21/compiling-hlsl-into-glsl-in-2010/comment-page-1/#comment-32355 Aras Pranckevičius Mon, 24 May 2010 04:41:29 +0000 http://aras-p.info/blog/?p=523#comment-32355 I want the compilation to happen purely offline. With Cg's GLSL translator, it seems to be designed to be used at runtime (so you'd use Cg runtime functions to manage programs, set uniforms etc.). I don't want to ship Cg runtime in my runtime :) (and Cg runtime on some platforms does not exist, e.g. iPhone or Android). Were you doing Cg to GLSL cross-compilation offline, without using the runtime? I want the compilation to happen purely offline. With Cg’s GLSL translator, it seems to be designed to be used at runtime (so you’d use Cg runtime functions to manage programs, set uniforms etc.). I don’t want to ship Cg runtime in my runtime :) (and Cg runtime on some platforms does not exist, e.g. iPhone or Android).

Were you doing Cg to GLSL cross-compilation offline, without using the runtime?

]]> By: n00body http://aras-p.info/blog/2010/05/21/compiling-hlsl-into-glsl-in-2010/comment-page-1/#comment-32348 n00body Mon, 24 May 2010 03:04:08 +0000 http://aras-p.info/blog/?p=523#comment-32348 Actually, I've been able to get Cg to produce working GLSL. I'm curious what went wrong with yours. Did you make sure to use cgCombinePrograms()? Actually, I’ve been able to get Cg to produce working GLSL. I’m curious what went wrong with yours. Did you make sure to use cgCombinePrograms()?

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