public static void DrawLine(Span <Rgba32> g, double x0, double y0, double x1, double y1, Rgba32 color, int width, int height)
{
bool steep = Math.Abs(y1 - y0) > Math.Abs(x1 - x0);
if (steep)
{
swap(ref x0, ref y0);
swap(ref x1, ref y1);
}
if (x0 > x1)
{
swap(ref x0, ref x1);
swap(ref y0, ref y1);
}
double dx = x1 - x0;
double dy = y1 - y0;
double gradient = dy / dx;
// handle first endpoint
double xend = Math.Round(x0);
double yend = y0 + gradient * (xend - x0);
double xgap = rfpart(x0 + 0.5);
double xpxl1 = xend; // this will be used in the main loop
double ypxl1 = ipart(yend);
if (steep)
{
DrawingUtils.SetPixel(g, ypxl1, xpxl1, new Rgba32(color.R, color.G, color.B, Convert.ToSingle(rfpart(yend) * xgap)), width, height);
DrawingUtils.SetPixel(g, ypxl1 + 1, xpxl1, new Rgba32(color.R, color.G, color.B, Convert.ToSingle(fpart(yend) * xgap)), width, height);
}
else
{
DrawingUtils.SetPixel(g, xpxl1, ypxl1, new Rgba32(color.R, color.G, color.B, Convert.ToSingle(rfpart(yend) * xgap)), width, height);
DrawingUtils.SetPixel(g, xpxl1, ypxl1 + 1, new Rgba32(color.R, color.G, color.B, Convert.ToSingle(fpart(yend) * xgap)), width, height);
}
// first y-intersection for the main loop
double intery = yend + gradient;
// handle second endpoint
xend = Math.Round(x1);
yend = y1 + gradient * (xend - x1);
xgap = fpart(x1 + 0.5);
double xpxl2 = xend; // this will be used in the main loop
double ypxl2 = ipart(yend);
if (steep)
{
DrawingUtils.SetPixel(g, ypxl2, xpxl2, new Rgba32(color.R, color.G, color.B, Convert.ToSingle(rfpart(yend) * xgap)), width, height);
DrawingUtils.SetPixel(g, ypxl2 + 1, xpxl2, new Rgba32(color.R, color.G, color.B, Convert.ToSingle(fpart(yend) * xgap)), width, height);
}
else
{
DrawingUtils.SetPixel(g, xpxl2, ypxl2, new Rgba32(color.R, color.G, color.B, Convert.ToSingle(rfpart(yend) * xgap)), width, height);
DrawingUtils.SetPixel(g, xpxl2, ypxl2 + 1, new Rgba32(color.R, color.G, color.B, Convert.ToSingle(fpart(yend) * xgap)), width, height);
}
if (steep)
{
for (double x = xpxl1 + 1; x <= xpxl2 - 1; x++)
{
DrawingUtils.SetPixel(g, ipart(intery), x, new Rgba32(color.R, color.G, color.B, Convert.ToSingle(rfpart(intery))), width, height);
DrawingUtils.SetPixel(g, ipart(intery) + 1, x, new Rgba32(color.R, color.G, color.B, Convert.ToSingle(fpart(intery))), width, height);
intery = intery + gradient;
}
}
else
{
for (double x = xpxl1 + 1; x <= xpxl2 - 1; x++)
{
DrawingUtils.SetPixel(g, x, ipart(intery), new Rgba32(color.R, color.G, color.B, Convert.ToSingle(rfpart(intery))), width, height);
DrawingUtils.SetPixel(g, x, ipart(intery) + 1, new Rgba32(color.R, color.G, color.B, Convert.ToSingle(fpart(intery))), width, height);
intery = intery + gradient;
}
}
}
/// <summary>
/// Draws a line between two points using Bresenham's algorithm with a thickness of 1 pixel
/// </summary>
/// <remarks>Algorithm from http://tech-algorithm.com/articles/drawing-line-using-bresenham-algorithm/</remarks>
/// <param name="image"></param>
/// <param name="x1"></param>
/// <param name="y1"></param>
/// <param name="x2"></param>
/// <param name="y2"></param>
/// <param name="color"></param>
public static void DrawLine(Span <Rgba32> image, float x1, float y1, float x2, float y2, Rgba32 color, int width, int height)
{
float w = x2 - x1;
float h = y2 - y1;
int dx1 = 0, dy1 = 0, dx2 = 0, dy2 = 0;
if (w < 0)
{
dx1 = -1;
}
else if (w > 0)
{
dx1 = 1;
}
if (h < 0)
{
dy1 = -1;
}
else if (h > 0)
{
dy1 = 1;
}
if (w < 0)
{
dx2 = -1;
}
else if (w > 0)
{
dx2 = 1;
}
float longest = Math.Abs(w);
float shortest = Math.Abs(h);
if (!(longest > shortest))
{
longest = Math.Abs(h);
shortest = Math.Abs(w);
if (h < 0)
{
dy2 = -1;
}
else if (h > 0)
{
dy2 = 1;
}
dx2 = 0;
}
float numerator = (int)longest >> 1;
for (int i = 0; i <= longest; i++)
{
DrawingUtils.SetPixel(image, x1, y1, color, width, height);
numerator += shortest;
if (!(numerator < longest))
{
numerator -= longest;
x1 += dx1;
y1 += dy1;
}
else
{
x1 += dx2;
y1 += dy2;
}
}
}