Hello SDL2 community!
Okay, first time posting anything at any forum in general, so please forgive me if I did something wrong…
I’m generally not the type to ask others for help, because I always try to solve my problems myself, BUT I ran out of ideas and the documentation isn’t helping anymore.
I already read through every post I could find on render batching / 2D drawing with SDL2 that had something to do with my problem.
My problem - short version: (if someone wants more info -> just ask 
I’m really trying to keep this post short )
I’m loading a .png with SDL_Image and drawing the png to a window (in a loop and every frame I draw x|y + 1 more – just for testing right now).
I set “SDL_SetHint(SDL_HINT_RENDER_BATCHING, “1”)”,but it’s still too slow?
Well I guess I’m doing something wrong. / My thought process is wrong.
(in my real code I’m drawing multiple layers of 2D pictures, but when I noticed it worked MUCH too slow, I started reading about render batching and such. Until then I didn’t know anything about render batching)
From what I read about render batching I get that it waits until it gets told to transmit information to the GPU and then it just tells the GPU what to draw where in a giant ‘list’. So I thought because I’m not changing neither the source texture nor the destination window, that it should work extremely fast.
But it seems like I got something wrong there.
My test code: (to keep the test code short I just assume that initialization works)
#include <iostream>
#include <SDL.h>
#include <SDL_image.h>
int main(int argc, char* argv[])
{
SDL_Init(SDL_INIT_EVERYTHING);
IMG_Init(IMG_INIT_PNG);
SDL_SetHint(SDL_HINT_RENDER_BATCHING, "1");
SDL_Window* window = NULL;
SDL_Surface* screenSurface = NULL;
SDL_Texture* graphic = NULL;
SDL_Renderer* gRenderer = NULL;
window = SDL_CreateWindow("test_render_batching", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 1000, 500, SDL_WINDOW_SHOWN);
screenSurface = SDL_GetWindowSurface(window);
SDL_FillRect(screenSurface, NULL, SDL_MapRGB(screenSurface->format, 0xFF, 0xFF, 0xFF));
SDL_UpdateWindowSurface(window);
gRenderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
SDL_SetRenderDrawColor(gRenderer, 0xFF, 0xFF, 0xFF, 0xFF);
SDL_Surface* tempSurface = NULL;
tempSurface = IMG_Load("stick.png");
graphic = SDL_CreateTextureFromSurface(gRenderer, tempSurface);
SDL_FreeSurface(tempSurface);
int count = 0;
Uint32 start_time = 0;
Uint32 stop_time = 0;
float offset = 0.0f;
while (true)
{
start_time = SDL_GetTicks();
SDL_RenderClear(gRenderer);
for (int x = 0; x < count; x++)
{
for (int y = 0; y < count; y++)
{
SDL_Rect dstrect;
dstrect.w = 50,
dstrect.h = 50,
dstrect.x = x,
dstrect.y = y;
SDL_RenderCopyEx(gRenderer, graphic, NULL, &dstrect, 0, 0, SDL_FLIP_NONE);
}
}
SDL_RenderPresent(gRenderer);
stop_time = SDL_GetTicks();
offset = (1000.0f/60) - (stop_time - start_time);
if (offset > 0)
{
SDL_Delay(offset);
}
else
{
char e;
std::cout << "amount = " << count << "\n";
std::cin >> e;
break;
}
count++;
}
SDL_DestroyWindow(window);
SDL_DestroyTexture(graphic);
SDL_DestroyRenderer(gRenderer);
IMG_Quit();
SDL_Quit();
return 0;
}
The .png to be loaded for this test: (did I do that right with copying the .png?)
(png should be transparent except for the stick)
I would REALLY appreciate it if someone could please sacrifice some time to help my tortured soul lol.
please I’ suffering, I really want to know what I got wrong, because I’m trying to fix it since at least 1.5 month now…
Best regards
Jakob
