archeus/src/graphics/sdl/circle.c

#ifdef ARC_SDL
#include "arc/graphics/circle.h"
#include "arc/graphics/sdl/renderer.h"
#include <stdlib.h>

//Modified from https://stackoverflow.com/questions/38334081/how-to-draw-circles-arcs-and-vector-graphics-in-sdl
void ARC_Circle_Render(ARC_Circle *circle, ARC_Renderer *renderer, ARC_Color *color){
    SDL_SetRenderDrawColor((SDL_Renderer *)renderer, color->r, color->g, color->b, color->a);

    int32_t diameter = (circle->r * 2);

    int32_t x = (circle->r - 1);
    int32_t y = 0;
    int32_t tx = 1;
    int32_t ty = 1;
    int32_t error = (tx - diameter);

    while(x >= y){
        //  Each of the following renders an octant of the circle
        SDL_RenderDrawPoint((SDL_Renderer *)renderer, circle->x + x, circle->y - y);
        SDL_RenderDrawPoint((SDL_Renderer *)renderer, circle->x + x, circle->y + y);
        SDL_RenderDrawPoint((SDL_Renderer *)renderer, circle->x - x, circle->y - y);
        SDL_RenderDrawPoint((SDL_Renderer *)renderer, circle->x - x, circle->y + y);
        SDL_RenderDrawPoint((SDL_Renderer *)renderer, circle->x + y, circle->y - x);
        SDL_RenderDrawPoint((SDL_Renderer *)renderer, circle->x + y, circle->y + x);
        SDL_RenderDrawPoint((SDL_Renderer *)renderer, circle->x - y, circle->y - x);
        SDL_RenderDrawPoint((SDL_Renderer *)renderer, circle->x - y, circle->y + x);

        if(error <= 0){
            ++y;
            error += ty;
            ty += 2;
        }

        if(error > 0){
            --x;
            tx += 2;
            error += (tx - diameter);
        }
    }
}

//TODO: very temp
void ARC_Circle_RenderFill(ARC_Circle *circle, ARC_Renderer *renderer, ARC_Color *color){
    ARC_Circle temp = *circle;

    for(; temp.r; temp.r--){
        ARC_Circle_Render(&temp, renderer, color);
    }
}

#endif // ARC_SDL