Lloyd Bryant
SDL_CreateTexture() is succeeding (i.e. returning a valid pointer) when the requested horizontal or vertical size of the texture exceeds the maximum allowed by the render. This results in hard-to-understand errors showing up when later attempting to use that texture (such as with SDL_SetRenderTarget()).
Added a reference to SDL_Direct3D9GetAdapterIndex to SDL_test_common.c so SDL will fail to compile if the new symbol isn't included properly.
CR: Jorgen
From Sythical:
Hello, I've created a simple SDL2 application which draws a texture on the screen. The problem I'm having is that if I launch another program which loads the UAC popup or if I lock my PC and then login again, the application stops drawing the texture. I tried adding SDL_Delay(10000) after SDL_RenderPresent(renderer). This made the texture stay on the screen for a little bit but the texture wasn't drawn again after the delay. Here's my code:
#include "SDL.h"
int main(int argc, char *argv[])
{
SDL_Renderer *renderer;
SDL_Window *window;
SDL_Surface *surface;
SDL_Texture *rect_texture;
SDL_Event main_event;
SDL_Rect rect_data;
int enable_vsync = 1;
if(SDL_Init(SDL_INIT_VIDEO) < 0) return 1;
window = SDL_CreateWindow("SDL2 Application", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 600, 600, SDL_WINDOW_RESIZABLE);
renderer = SDL_CreateRenderer(window, -1, enable_vsync ? SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC : SDL_RENDERER_ACCELERATED);
SDL_SetRenderDrawColor(renderer, 20, 20, 30, 255);
surface = SDL_LoadBMP("icon.bmp");
rect_texture = SDL_CreateTextureFromSurface(renderer, surface);
rect_data.w = 32; rect_data.h = 32;
rect_data.x = 300; rect_data.y = 300;
while(main_event.type != SDL_QUIT)
{
SDL_PollEvent(&main_event);
SDL_RenderClear(renderer);
SDL_RenderCopy(renderer, rect_texture, NULL, &rect_data);
SDL_RenderPresent(renderer);
}
SDL_DestroyTexture(rect_texture);
SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}
driedfruit
SDL_RenderCopy clips dstrect against the viewport. Then it adjusts the
srcrect by "appropriate" amount of pixels. This amount is actually
wrong, quite a lot, because of the rounding errors introduced in the "*
factor / factor" scale.
real_srcrect.x += (deltax * real_srcrect.w) / dstrect->w;
real_srcrect.w += (deltaw * real_srcrect.w) / dstrect->w;
For example:
I have a 32 x 32 srcrect and a 64 x 64 dstrect. So far the
stretching is done perfectly, by a factor of 2.
Now, consider dstrect being clipped against the viewport, so it becomes
56 x 64. Now, the factor becomes 1.75 ! The adjustment to "srcrect"
can't handle this, cause srcrect is in integers.
And thus we now have incorrect mapping, with dstrect not being in the
right proportion to srcrect.
The problem is most evident when upscaling stuff, like displaying a 8x8
texture with a zoom of 64 or more, and moving it beyond the corners of
the screen. It *looks* really really bad.
Note: RenderCopyEX does no such clipping, and is right to do so. The fix would be to remove any such clipping from RenderCopy too. And then fix the software renderer, because it has the same fault, independently of RenderCopy.
[attached patch]
this leaves Software Renderer buggy, as it does it's own clipping later on
