public static void DrawScreenCircle(this FrameState frame, int x0, int y0, int radius, Color color)
{
void DrawPoint(int xn, int yn)
{
frame.DrawScreenPoint(xn, yn, color);
}
var x = radius;
var y = 0;
var radiusError = 1 - x;
while (x >= y)
{
DrawPoint(x + x0, y + y0);
DrawPoint(y + x0, x + y0);
DrawPoint(-x + x0, y + y0);
DrawPoint(-y + x0, x + y0);
DrawPoint(-x + x0, -y + y0);
DrawPoint(-y + x0, -x + y0);
DrawPoint(x + x0, -y + y0);
DrawPoint(y + x0, -x + y0);
y++;
if (radiusError < 0)
{
radiusError += 2 * y + 1;
}
else
{
x--;
radiusError += 2 * (y - x + 1);
}
}
}
public static void DrawScreenLineSmooth(this FrameState frame, int x0, int y0, int x1, int y1, Color color)
{
void DrawScreenPoint(bool swap, int vx, int vy, float intensity)
{
if (swap)
{
Common.Swap(ref vx, ref vy);
}
frame.DrawScreenPoint(vx, vy, color.ChangeAlpha((byte)(intensity * color.A)));
}
var steep = NormalizeLine(ref x0, ref y0, ref x1, ref y1);
DrawScreenPoint(steep, x0, y0, 1);
DrawScreenPoint(steep, x1, y1, 1);
var dx = x1 - x0;
var dy = y1 - y0;
var gradient = (float)dy / dx;
var y = y0 + gradient;
for (var x = x0 + 1; x < x1; x++)
{
DrawScreenPoint(steep, x, (int)y, 1 - (y - (int)y));
DrawScreenPoint(steep, x, (int)y + 1, y - (int)y);
y += gradient;
}
}
public static void DrawScreenLine(this FrameState frame, int x0, int y0, int x1, int y1, Color color)
{
var steep = NormalizeLine(ref x0, ref y0, ref x1, ref y1);
var dx = x1 - x0;
var dy = Math.Abs(y1 - y0);
var error = dx / 2;
var ystep = (y0 < y1) ? 1 : -1;
var y = y0;
for (var x = x0; x <= x1; x++)
{
frame.DrawScreenPoint(steep ? y : x, steep ? x : y, color);
error -= dy;
if (error < 0)
{
y += ystep;
error += dx;
}
}
}