CODEWITHSUNDEEP
c++texturessdl-2pixel
Joe Fanelli
Joe Fanelli

Reputation: 41

Manipulating hardware textures with SDL2

Why do I have to use SDL_LockTexture and SDL_UnlockTexture to manipulate hardware textures with SDL2? I am aware of the difference between "STATIC" texture access and "STREAMING" texture access, but I guess I am confused because I seem to remember using "SDL_SetTextureColorMod" to adjust the color of "STATIC" textures. So, why is it that sometimes we have to lock pixels and sometimes we don't?

Upvotes: 1

Views: 487

Answers (1)

joe_chip
joe_chip

Reputation: 2558

You have to lock a texture in order to modify its pixels. SDL_SetTextureColorMod doesn't do this, it only sets a color which is multiplied with color of a pixel when the texture is used for rendering.

Why do I have to use SDL_LockTexture and SDL_UnlockTexture to manipulate hardware textures?

"Hardware texture" means that pixels of a texture are stored in VRAM and can be directly accessed by a GPU when rendering. You can't modify VRAM memory directly. SDL_LockTexture returns pointer to buffer accessible by CPU, while SDL_UnlockTexture copies this (modified) buffer back to VRAM.

Upvotes: 6

Related Questions