Wondering if my implementation is a good way to go about this pixel simulation

Game Development
1

Hello! I am new to coding with graphics. I’ve made a sand simulation in PyGame and I decided to rewrite it in SDL.

Before I code any further… I had a couple of concerns with my implementation.

I am directly working with the pixels by updating their colors using SDL_SetRenderDrawColor() and SDL_RenderDrawPoint(). No textures.

However, I am looping through the screen multiple times. Once to move elements that can be moved, and again to draw them.

I suspect I am thinking about this implementation inefficiently. I have no frame cap right now, but currently the screen width and height are set to 250, but when I move it up to something like 500, the simulation is very slow and I suspect it is due to the implementation I currently have for drawing the pixels.

I was wondering if anyone could provide me with some insight on creating a pixel-based game such as this? I’d appreciate some higher level abstraction, I just want to get better at coding in general.

Here is my Github repo with my full source code if anyone wants to take a look! Thank you very much.

2

I think drawing lots of pixels with SDL_RenderDrawPoint would be very slow and you’d be better off with SDL_RenderDrawPoints. See:

https://wiki.libsdl.org/SDL_RenderDrawPoints

3

Thanks for your reply!

How would I go about setting the color of each pixel if I’m drawing them all at once?

I was previously setting the draw color then rendering the pixel. If I’m rendering them in a batch, I’m not sure how to go about setting individual colors.

4

I’d draw all the pixels that are gonna be the same colour in batches.

5

Board::Board is leaking memory, by using new and not delete. push_back doesn’t move, it just copies de content. Just use ‘Tile t;’ instead: it would be build on stack (much faster) and you won’t need to delete it. Avoid pointer until you will be forced to use it.
There’s no point in making a Tile class just to have a pointer to Element. If you just want another name, use ‘using Tile = Element;’.
Untie those if/elses inside main, they only make things less readable and prone to errors.

6

Directly working with the pixels is involved in software rendering. Therefore, the image to be rendered should be in a format accessible to the CPU, in this case a C++ array, where reading/writing a pixel involves an array access. In SDL2, it is possible to access the video image by the window surface:

SDL_Surface* screenSurface = SDL_GetWindowSurface(window);
uint32_t* bitmapdata = (uint32_t*)screenSurface->pixels;
int width=screenSurface->w; int height=screenSurface->h;

Example renderer for draw chessboard:

for(int j=0;j<height;j++)for(int i=0;i<width;i++)bitmapdata[j*width+i]=((i*8/width)^(j*8/height))&1?0xFFFFFF:0x000000;

Then use SDL_UpdateWindowSurface(window); on each frame to display the image.

And to handle resize events:

SDL_Event event_;
while (SDL_PollEvent(&event_)){
 if(event_.type==SDL_QUIT)exit(0);
 if((event_.type==SDL_WINDOWEVENT)&&(event_.window.event==SDL_WINDOWEVENT_SIZE_CHANGED)){screenSurface=SDL_GetWindowSurface(window);width=screenSurface->w;height=screenSurface->h;bitmapdata=(uint32_t*)screenSurface->pixels;}
}