Raylib: [shapes] DrawArc

[DarkElvenAngel]

I can't seem to find a way to draw arcs filled or otherwise. I working around this by cutting the circle with a rectangle that works fine till you want to use the alpha channel.

[Demizdor]

Look at DrawCircleV() from shapes.c, it's fairly easy to modify it to draw arcs.

Maybe adding functions like DrawArc() and DrawArcLines() will be useful in the future.

[Demizdor]

Actually there are many ways to draw arcs by using raylib built-in functions, just made this quick thing using DrawPolyEx()

void DrawArc(Vector2 center, float radius, int startAngle, int endAngle, Color color) {
    #define SEGMENTS 16

    //angle between 0...359
    startAngle %= 360;
    endAngle %= 360;

    //calculate segment point coordinates for the arc
    Vector2 points[SEGMENTS+3];
    int step = (endAngle-startAngle)/(SEGMENTS-1);
    step = (step <= 0) ? 1 : step;

    float angle = startAngle;
    for(int i = 1; i<SEGMENTS; i++) {
        points[i].x = center.x + cosf(DEG2RAD*(360-angle))*radius;
        points[i].y = center.y + sinf(DEG2RAD*(360-angle))*radius;
        //DrawLine(center.x, center.y, points[i].x, points[i].y, i==1?BLUE:RED); //to visualize the lines
        angle += step;
    }
    points[0] = center;
    points[SEGMENTS] = (Vector2){center.x + cosf(DEG2RAD*(360-endAngle))*radius, center.y + sinf(DEG2RAD*(360-endAngle))*radius};
    points[SEGMENTS+1] = center;

    //DrawLine(center.x, center.y, points[SEGMENTS].x, points[SEGMENTS].y, RED); //to visualize the lines
    DrawPolyEx(&points, SEGMENTS+3, color);
}

Use it like this DrawArc((Vector2){200,200}, 120, 20, 320, Fade(GOLD, 0.6)); to create a pacman ;)

[DarkElvenAngel]

That's for the tip I did look at shape.c and it looks easy enough to modify. My only thought is if I modify the library I have to very careful about portability.

That function is spot on and a great place to start.

Thanks very much.

[DarkElvenAngel]

I found that you don't need these lines
//angle between 0...359
startAngle %= 360;
endAngle %= 360;
And without them you can draw any arc from any point.

Now to solve for ellipse...

[raysan5]

@Demizdor @DarkElvenAngel Feel free to send a PR with DrawArc() and DrawArcLines(). :)

[raysan5]

Just reviewing this issue... noticed that DrawCircleSector() (a pacman or circle piece) can be accomplished just adapting DrawCircleV(), actually it already draws quads/triangles every 10 degrees to create the circle...

But supporting DrawArc() (like a ring, with inner radius and outer radius) is a bit more complex.

[raysan5]

DrawCircleSector() redesigned in commit https://github.com/raysan5/raylib/commit/88dfd2ab236a28db3cf1e3715b9e98a426de48d6.

@Demizdor Feel free to send your DrawRing() implementation!

[raysan5]

Closing this issue! Thanks @Demizdor!