Create functions to save/restore render state

[SDLBugzilla]

This bug report was migrated from our old Bugzilla tracker.

Reported in version: HG 2.1
Reported for operating system, platform: All, All

Comments on the original bug report:

On 2011-02-20 12:22:19 +0000, Sam Lantinga wrote:

It should be possible to use SDL rendering with native OpenGL or Direct3D.

This task is to create functions to save and restore render state so 2D rendering can be mixed with 3D rendering. e.g.

while (true) {
3D rendering...
SDL_RenderSaveState()
2D rendering...
SDL_RenderRestoreState()
3D present
}

We'll also need some test programs for this using the various native 3D APIs.

On 2013-05-21 09:34:48 +0000, Gabriel Jacobo wrote:

I've done a bit of this here: http://mdqinc.com/blog/2013/01/integrating-librocket-with-sdl-2/ where I do the "resetting" to a known state by drawing a point outside of the screen. I ended up building SDL_RenderGeometry out of that code to be able to integrate with SDL's shader management (there's another wishlist item!), but the idea still holds...

Basically I think a solution could be implemented with a SDL_RenderResetState function which can be called before the 2D functions, something like...

app specific 3D rendering setup...
3D rendering
SDL_RenderResetState()
2D rendering (using SDL_Render* functions)
2D/3D present

On 2013-05-21 23:57:56 +0000, Sam Lantinga wrote:

That seems like a decent approach to me. :)

[1bsyl]

@slouken @icculus : with the batching SDL_Render, I wonder whether saving render state could be easily implemented:
SDL_RenderSaveState(): just do SDL_RendererFlush()
SDL_RenderRestoreState(): mark all internal variable '*_dirty' to '1'

[icculus]

Let's just add a function to say "I have invalidated the state" so it doesn't sound like they can save specific states off. Then this is simple enough we could probably even add it into SDL2.

[icculus]

Actually, we can probably just make an explicit Flush make all state dirty, since you would only call this before using GL/D3D directly. Implicit flushes (changing render targets, presenting, etc) won't dirty all the state.