Why can't I call this SDL2_gfxPrimitives function?
<p>I have no trouble using the SDL2 library to launch a window and draw a colored square on a black background. But when I try using the SDL2_gfx library to draw a circle the filledCircleColor() is undefined:</p>

<pre><code>make build;
make[1]: Entering directory `/home/mike/compile/sdlTest'
gcc -std=c99 -c sdlTest.c;
gcc sdlTest.o -o sdlTest -I/usr/include/SDL2 -lSDL2;
sdlTest.o: In function `main':
sdlTest.c:(.text+0x176): undefined reference to `filledCircleColor'
collect2: error: ld returned 1 exit status
make[1]: *** [build] Error 1
make[1]: Leaving directory `/home/mike/compile/sdlTest'
make: *** [test] Error 2
</code></pre>

<p>What am I doing wrong?</p>

<p>Here's my C:</p>

<pre><code>#include &lt;stdio.h&gt;
#include &lt;SDL2/SDL.h&gt;
#include &lt;SDL2/SDL2_gfxPrimitives.h&gt;


SDL_Event event;

//SDL2 variables
void* nullptr;
SDL_Window *win;
SDL_Renderer *ren;

int main(void) {
    if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
        printf("SDL_Init Error: %s\n", SDL_GetError());
    }

    win = SDL_CreateWindow("sdlTest", 100, 100, 10*32, 10*32, SDL_WINDOW_SHOWN);
    if (win == nullptr) {
        printf("SDL_CreateWindow Error: %s\n", SDL_GetError());
    }

    ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
    if (ren == nullptr) {
        printf("SDL_CreateRenderer Error: %s\n", SDL_GetError());
    }

    SDL_SetRenderDrawColor(ren, 0, 0, 0, 255);
    SDL_RenderClear(ren);


    SDL_Rect rect;
    rect.x = 20;
    rect.y = 20;
    rect.w = 10;
    rect.h = 10;

    SDL_SetRenderDrawColor(ren, 0, 0, 255, 255);
    SDL_RenderFillRect(ren, &amp;rect);


    filledCircleColor(ren, 50, 50, 50, 0xFF0000FF);

    SDL_RenderPresent(ren);

    while(1) { ; }
}
</code></pre>

<p>Here's my Makefile:</p>

<pre><code>test:
    make build;
    make run;

build:
    gcc -std=c99 -c sdlTest.c;
    gcc sdlTest.o -o sdlTest -I/usr/include/SDL2 -lSDL2;

run:
    ./sdlTest;

clean:
    -rm sdlTest;
    -rm *.o;
    -rm *~
</code></pre>

<p>I'm on a Linux box. Thanks for the help!</p>