Shaders for Dummies (I'm the dummy)

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chiekku

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Posted: 20th Sep 2010 04:49

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I'm a long time user of DarkBasic, DarkBasic Pro, and recent user of Dark GDK. I'm not very good at it, but DB has been an enjoyable intro to game programming. I recently switched over from Pro to DGDK, since my classes at college deal with C/C++.

I'm new to shaders, and am having trouble using them in DGDK, more specifically what commands to use when. There seem to be a lot:

dbCreateVertexShaderFromFile
dbCreatePixelShaderFromFile
dbLoadEffect
etc...

I don't know which of these commands to use, basically. I don't have Dark Shader, so I need to use shaders without it. For starters, I downloaded some shaders from NVIDIA's library found at: http://developer.download.nvidia.com/shaderlibrary/webpages/shader_library.html

In addition to not knowing which commands to use in GDK to apply shaders to objects or matrices, any progress I've made in applying a shader to an object has been met with DGDK crashing in the usual "has stopped working" fashion. From what little I understand about shaders, .DDS files are the textures, and the .fx or .cgfx files actually "shade" the .DDS textures. However, the game always crashes when I attempt to apply the shader effect (using "dbSetObjectEffect(51,52)").

Here's the code I've been trying to use that causes a crash:

+ Code Snippet

	dbMakeObjectPlane(51,5000,5000);
	dbLoadEffect("waves/Shading.fx",52,0);
	
	dbLoadImage("waves/Waves.dds",53);
	dbTextureObject(51,0,53);

	dbLoadImage("waves/Sky.dds",54,2);
	dbTextureObject(51,1,54);

	dbLoadImage("waves/Sea.dds",55,2);
	dbTextureObject(51,2,55);
	
	dbSetObjectEffect(51,52);

If someone could enlighten me on the basics of applying shaders in DGDK without the use of Dark Shader, I would appreciate it. I'm not looking for tutorials on how to write shaders from scratch (yet), just how to take an already existing shader and apply it to a surface with the DGTK commands as simply as possible.

tl;dr -> how do I use a shader on an object in DGDK?

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Dodga

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Posted: 20th Sep 2010 22:44

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That's alot easier to ask than it is to answer. The best thing I could recommend doing is going to http://www.evolved-software.com/shaders/shadowing
downloading the DarkGDK project files and learning from there. Not all shaders work the same, and some of them have specific ways you have to texture the objects, so it's not something easily answered in a forum post. Hope this helps.

The most BASIC thing I can tell you, is that every shader has certain perameters, called tweakables that can be adjusted with dbSetEffectValueFloat, and dbSetEffectValueVector, as well as certain techniques that you call to actually make the rendering happen with dbSetEffectTechnique. You can find all these values in the fx file by opening it in notepad. Some shaders also involve setting up multiple cameras and rendering the scene multiple times. It sounds complicated but if you study the source files above, you'll figure it out.

The other thing I can recommend is that you have to change all the 1_1 and 1_4's in the effect file to 2_0.

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Sixty Squares

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Posted: 21st Sep 2010 01:15 Edited at: 21st Sep 2010 01:16

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Also check out this thread for a bunch of shaders (any non-shader code will be for DBPro, but the shaders should work in DGDK and the DBPro code shouldn't be too hard to understand anyway):

The Learning To Write Shaders Shader Archive.

Included in that thread is a link to the "Learning To Write Shaders" thread, where people post their questions about shaders. There are also shader demos posted in that thread, which are referenced in the archive thread.

I started my shader quest here:
http://knol.google.com/k/hlsl-shaders#.

Then I went to EVOLVED's site ([href]www.evolved-software.com[/href]) and started messing around with some of his fullscreen shaders, changing the colors and whatnot.

Guns, cinematics, stealth, items and more!

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chiekku

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Posted: 21st Sep 2010 08:17

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Quote: "
The other thing I can recommend is that you have to change all the 1_1 and 1_4's in the effect file to 2_0.
"

That fixed it! From what I gather, that told the shader to render with Pixel Shader version 2 instead of 1.4. How did you know this would work?

Thank you