( ﾉ╹◡◡╹)ﾉ SDL2_gfx を使ったデモっぽいやつ

main.c

#include <stdio.h>
#include <SDL2/SDL.h>
#include <SDL2/SDL2_gfxPrimitives.h>

const int SCREEN_WIDTH  = 640;
const int SCREEN_HEIGHT = 480;

#define  ERROR_REPORT(_message_)                                    \
    fprintf( stderr, "%s:%d %s\n", __FILE__, __LINE__, _message_ )


int main(int argc, char ** argv) {
    if ( SDL_Init( SDL_INIT_EVERYTHING ) < 0 ) {
        ERROR_REPORT( SDL_GetError() );

        return -1;
    }

    SDL_Window   *window    = SDL_CreateWindow( "Hello, GFX",
                                                SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
                                                SCREEN_WIDTH, SCREEN_HEIGHT,
                                                SDL_WINDOW_OPENGL );

    /* SDL_Surface  *screen    = SDL_GetWindowSurface( window ); */
    SDL_Renderer *renderer  = SDL_GetRenderer( window );

    SDL_Color    white = { 0xff, 0xff, 0xff, 0xff };
    /* SDL_Color    black = { 0x00, 0x00, 0x00, 0xff }; */

    SDL_Point draw_points[] = {
        {  0,  5 },
        {  5,  5 },
        {  5, 11 },
        {  0, 11 }
    };

    /* SDL_FillRect( screen, NULL, SDL_MapRGB( screen->format, black.r, black.g, black.b ) ); */

    for ( int i = 0; i < 4; ++ i ) {
        int x1 = draw_points[i].x * (SCREEN_WIDTH / 16);
        int y1 = draw_points[i].y * (SCREEN_HEIGHT / 16);

        int x2 = draw_points[(i + 1) % 4].x * (SCREEN_WIDTH / 16);
        int y2 = draw_points[(i + 1) % 4].y * (SCREEN_HEIGHT / 16);

        printf( "(%3d, %3d) -> (%3d, %3d)\n", x1, y1, x2, y2 );
        printf( "red: %d, green: %d, blue: %d, alpha: %d\n", white.r, white.g, white.b, white.a );
            
        lineRGBA( renderer,
                  x1, y1,
                  x2, y2,
                  white.r, white.g, white.b, white.a );
    }
    SDL_RenderPresent( renderer );
    
    int         be_exit = 1;
    SDL_Event   an_event;
    do {
        if ( SDL_PollEvent( &an_event ) ) {
            switch ( an_event.type ) {
                case SDL_KEYDOWN:
                    be_exit = 0;
                    break;

                case SDL_QUIT:
                    be_exit = 0;
                    break;

                default:
                    break;
            }
        }
        SDL_Delay( 1 );

    } while ( be_exit );

    SDL_DestroyRenderer( renderer );
    SDL_DestroyWindow( window );
    SDL_Quit();

    return 0;
}

makefile

SDL2_INCLUDES  = $(shell pkg-config --cflags-only-I sdl2)
SDL2_DEFINES   = $(shell pkg-config --cflags-only-other sdl2)
SDL2_LIBS      = $(shell pkg-config --libs sdl2)

SDL2GFX_LIBS   = $(shell pkg-config --libs SDL2_gfx)

CFLAGS = -W -Wall -O2 $(DEFINES) $(INCLUDES)

INCLUDES = $(SDL2_INCLUDES)

DEFINES = $(SDL2_DEFINES)

LIBS = $(SDL2GFX_LIBS) $(SDL2_LIBS)

target = demo-sdl2-gfx

.PHONY : all
all: $(target)

$(target): main.o
	gcc $(LIBS) $^ -o $@

main.o: main.c
	gcc $(CFLAGS) -c $^ -o $@