Modifying Pixels For A Paint Program

If you insist on using DirectX (and assuming newer versions of DX, Direct3D), then yeah, locking the texture's surface and writing to it, and then unlocking it again , and finally using a quad to draw it would be the best. Make sure that you create the texture with D3DUSAGE_DYNAMIC. Actually, you might consider just locking the backbuffer and writing to that, but I don't know what the speed would be on that, and you'd lose all abilities to do layered effects and such.

As for speed with all the locking, dynamic textures are meant to be locked and unlocked a lot. And since you're only going to be doing this to a single texture at a time, and you're not trying to get 85 FPS out of it, then it probably ain't going to be a speed problem at all.

(Side thought about another benefit to using DirectX: Eventually, you could get around to having fun with pixel shaders to apply hardware accelerated effects to your images.)

However, using a 3D API to write a paint program seems a little odd, unless you find some uses for the API that standard bitmaps can't do, such as really easy alpha blending for layers or something. I'd just recommend sticking with the standard Win32 device contexts and bitmaps, and things like bitblt. But for you, that might require learning new stuff rather than using what you already know. Which isn't necessarily a bad thing, but if you're lazy, I'm no one to criticize you. [smile]

I know theres an HLSL paint sample in the DX SDK. I'm unsure exactly how it works (a bit over my head), but I'm quite positive it provides better results than the other methods. Assuming your up to it, I'd take a look at how it's done there.

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Original post by sirob I know theres an HLSL paint sample in the DX SDK. I'm unsure exactly how it works (a bit over my head), but I'm quite positive it provides better results than the other methods. Assuming your up to it, I'd take a look at how it's done there.

I know NVidia FX Composer comes with one where you can draw on a teapot.

yes, that's the one I mean - got the origin of it mixed up thanks :).

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However, using a 3D API to write a paint program seems a little odd, unless you find some uses for the API that standard bitmaps can't do, such as really easy alpha blending for layers or something. I'd just recommend sticking with the standard Win32 device contexts and bitmaps, and things like bitblt. But for you, that might require learning new stuff rather than using what you already know. Which isn't necessarily a bad thing, but if you're lazy, I'm no one to criticize you.

Layering (like Adobe PS and PS Pro) would be a very easy task as well.

you could try GetBitmapBits/SetBitmapBits, but i dont know how fast this is