This is the OpenGL line drawing fix for Bugzilla #3182, but there's some
disagreement about what the renderers should do here, so I'm backing this out
until after 2.0.12 ships, and then we'll reevaluate all the renderer backends
to decide what's correct, and make them all work the same.
Likewise for the GLES1 and GLES2 renderers.
This solves the missing pixel at the end of a line and removes all the
heuristics for various platforms/drivers. It's possible we could still use
GL_LINE_STRIP with this and save some vertex buffer space, assuming this
doesn't upset some driver somewhere, but this seems to be a clean fix that
makes the GL renderers match the software renderer output.
Diamond-exit rule explanation:
http://graphics-software-engineer.blogspot.com/2012/04/rasterization-rules.html
Fixes Bugzilla #3182.
Konrad
This kind of blending is rather quite useful and in my opinion should be available for all renderers. I do need it myself, but since I didn't want to use a custom blending mode which is supported only by certain renderers (e.g. not in software which is quite important for me) I did write implementation of SDL_BLENDMODE_MUL for all renderers altogether.
SDL_BLENDMODE_MUL implements following equation:
dstRGB = (srcRGB * dstRGB) + (dstRGB * (1-srcA))
dstA = (srcA * dstA) + (dstA * (1-srcA))
Background:
https://i.imgur.com/UsYhydP.png
Blended texture:
https://i.imgur.com/0juXQcV.png
Result for SDL_BLENDMODE_MOD:
https://i.imgur.com/wgNSgUl.png
Result for SDL_BLENDMODE_MUL:
https://i.imgur.com/Veokzim.png
I think I did cover all possibilities within included patch, but I didn't write any tests for SDL_BLENDMODE_MUL, so it would be lovely if someone could do it.
Konrad
This was something rather trivial to add, but asked at least several times before (I did google about it as well).
It should be possible to dynamically change scaling mode of the texture. It is actually trivial task, but until now it was only possible with a hint before creating a texture.
I needed it for my game as well, so I took the liberty of writing it myself.
This patch adds following functions:
SDL_SetTextureScaleMode(SDL_Texture * texture, SDL_ScaleMode scaleMode);
SDL_GetTextureScaleMode(SDL_Texture * texture, SDL_ScaleMode *scaleMode);
That way you can change texture scaling on the fly.
warning: either cast from 'int' to 'size_t' (aka 'unsigned long') is ineffective, or there is loss of precision before the conversion [bugprone-misplaced-widening-cast]
Sylvain
I think what happening with the software renderer is:
* you're somehow in background (so texture creation is not possible)
* it resizes and wants to push a SDL_WINDOWEVENT_SIZE_CHANGED
It call:
https://hg.libsdl.org/SDL/file/a010811d40dd/src/render/SDL_render.c#l683
* GetOutputSize
* SW_GetOutputSize
* SW_ActivateRenderer
* SDL_GetWindowSurface
* SDL_CreateWindowFramebuffer which is mapped to SDL_CreateWindowTexture
and it ends up re-creating the surface/a texture, while being in background
