public static List <List <Vector2i> > ScanAlignY(List <Vector2i> poly)
{
List <List <Vector2i> > results = new List <List <Vector2i> >();
Vector2i max = new Vector2i(int.MinValue, int.MinValue);
Vector2i min = new Vector2i(int.MaxValue, int.MaxValue);
foreach (Vector2i v in poly)
{
max = Vector2i.Max(v, max);
min = Vector2i.Min(v, min);
}
List <Vector2i> trans = poly.Select(t => { return(t - min); }).ToList();
int height = max[1] - min[1];
List <ScanEdge> scanLines = new List <ScanEdge>();
int count = trans.Count;
int count1 = count - 1;
for (int i = 0; i < count; ++i)
{
Vector2i ps = trans[i];
int post = (i + 1) % count;
Vector2i pe = trans[post];
if (ps[1] == pe[1]) // 水平 去掉
{
Vector2i hori = Vector2i.GetVector2i(ps[0], pe[0]);
List <Vector2i> result = new List <Vector2i>();
for (int hi = hori[0]; hi <= hori[1]; ++hi)
{
result.Add(new Vector2i(hi, ps[1]));
}
if (result.Count > 0)
{
result = result.Select(t => { return(t + min); }).ToList();
results.Add(result);
}
continue;
}
int pre = (i + count1) % count;
Vector2i pss = trans[pre];
int ppost = (post + 1) % count;
Vector2i pee = trans[ppost];
double dx = (ps[0] - pe[0]) * 1.0f / (ps[1] - pe[1]);
bool yiG0 = ps[1] < pe[1];
double startX = yiG0 ? ps[0] : pe[0];
int ymin = yiG0 ? ps[1] : pe[1];
int ymax = yiG0 ? pe[1] : ps[1];
if (pe[1] > ps[1])
{
if (pee[1] >= pe[1])
{
ymax -= 1;
}
}
else
{
if (pss[1] >= ps[1])
{
ymax -= 1;
}
}
ScanEdge ep = new ScanEdge();
ep.mMinY = ymin;
ep.mMaxY = ymax;
ep.mStartX = startX;
ep.mDx = dx;
scanLines.Add(ep);
}
for (int i = 0; i < height; ++i)
{
List <Vector2i> result = new List <Vector2i>();
List <ScanEdge> tmp = scanLines.FindAll(delegate(ScanEdge line) { return(line.Include(i)); });
tmp.Sort((e1, e2) =>
{
//此处可以不考虑 斜率。 x相等时，不用考虑谁在前谁在后
return(e1.mStartX.CompareTo(e2.mStartX));
});
if (tmp.Count % 2 != 0)
{
throw new Exception("必须是偶数");
}
for (int idx = 0; idx < tmp.Count; idx += 2)
{
int next = idx + 1;
int x1 = (int)tmp[idx].mStartX;
int x2 = (int)tmp[next].mStartX;
if (x1 > x2)
{
continue;
}
for (int xi = x1; xi <= x2; ++xi)
{
result.Add(new Vector2i(xi, i));
}
tmp[idx].Increase();
tmp[next].Increase();
}
scanLines.RemoveAll((t) => t.mMaxY == i);
if (result.Count > 0)
{
result = result.Select(t => { return(t + min); }).ToList();
results.Add(result);
}
}
return(results);
}
protected void DrawScreenSpaceTriangleInterpolated(PreparedTriangle triangle)
{
WriteableBitmap rt = _renderWindow.Framebuffer;
if (triangle.GetScreenSpaceDirection() != VisibleTriangleDirection)
{
return;
}
var triangleArea = CalculateTriangleArea(
triangle.Vertices[0].X, triangle.Vertices[0].Y,
triangle.Vertices[1].X, triangle.Vertices[1].Y,
triangle.Vertices[2].X, triangle.Vertices[2].Y);
var vertexX = new double[] { triangle.Vertices[0].X, triangle.Vertices[1].X, triangle.Vertices[2].X };
var vertexY = new double[] { triangle.Vertices[0].Y, triangle.Vertices[1].Y, triangle.Vertices[2].Y };
var scanEdges = new List <ScanEdge>();
for (int current = 0; current < 3; ++current)
{
int next = (current + 1) % 3;
double higherx, highery;
double lowerx, lowery;
if (vertexY[current] < vertexY[next])
{
higherx = vertexX[current];
highery = vertexY[current];
lowerx = vertexX[next];
lowery = vertexY[next];
}
else
{
higherx = vertexX[next];
highery = vertexY[next];
lowerx = vertexX[current];
lowery = vertexY[current];
}
int minY = (int)highery;
int maxY = (int)lowery;
//int startX = (int)higherx;
//int endX = (int)lowerx;
if (minY == maxY)
{
continue;
}
var scanEdge = new ScanEdge();
scanEdge.MinimalY = (int)Math.Ceiling(highery);
scanEdge.MaximalY = (int)Math.Ceiling(lowery);
scanEdge.X = higherx;
scanEdge.XSlope = (lowerx - higherx) / ((double)(lowery - highery));
scanEdges.Add(scanEdge);
}
if (scanEdges.Count == 0)
{
return;
}
scanEdges = scanEdges.OrderBy(t => t.MinimalY).ToList();
int scanEdgesActivated = 0;
var startY = Math.Max(scanEdges.Min(t => t.MinimalY), 0);
var endY = Math.Min(scanEdges.Max(t => t.MaximalY), rt.PixelHeight - 1);
var activeEdges = new List <ScanEdge>();
for (var y = startY; y <= endY; ++y)
{
activeEdges = activeEdges.Where(t => y < t.MaximalY).ToList();
while (scanEdgesActivated < scanEdges.Count)
{
if (y < scanEdges[scanEdgesActivated].MinimalY)
{
break;
}
activeEdges.Add(scanEdges[scanEdgesActivated]);
++scanEdgesActivated;
}
activeEdges = activeEdges.OrderBy(t => t.X).ToList();
for (int i = 0; i < activeEdges.Count - 1; i += 2)
{
int startX = (int)Math.Ceiling(Math.Max(activeEdges[i].X, 0));
int endX = (int)Math.Floor(Math.Min(activeEdges[i + 1].X, rt.PixelWidth - 1));
for (int x = startX; x <= endX; ++x)
{
var aArea = CalculateTriangleArea(
x, y,
triangle.Vertices[1].X, triangle.Vertices[1].Y,
triangle.Vertices[2].X, triangle.Vertices[2].Y);
var bArea = CalculateTriangleArea(
triangle.Vertices[0].X, triangle.Vertices[0].Y,
x, y,
triangle.Vertices[2].X, triangle.Vertices[2].Y);
var cArea = CalculateTriangleArea(
triangle.Vertices[0].X, triangle.Vertices[0].Y,
triangle.Vertices[1].X, triangle.Vertices[1].Y,
x, y);
var fa = Math.Min(aArea / triangleArea, 1.0);
var fb = Math.Min(bArea / triangleArea, 1.0);
var fc = Math.Min(cArea / triangleArea, 1.0);
if (fa + fb + fc > 1.0)
{
int lowestAreaIndex = 0;
double lowestArea = fa;
if (lowestArea > fb)
{
lowestAreaIndex = 1;
lowestArea = fb;
}
if (lowestArea > fc)
{
lowestAreaIndex = 2;
lowestArea = fc;
}
switch (lowestAreaIndex)
{
case 0:
fa = 1.0 - fb - fc;
break;
case 1:
fb = 1.0 - fa - fc;
break;
case 2:
fc = 1.0 - fa - fb;
break;
}
}
var z = fa * triangle.Vertices[0].Z
+ fb * triangle.Vertices[1].Z
+ fc * triangle.Vertices[2].Z;
if (z <= 1.0)
{
continue;
}
if (_zBuffer[x, y] > z)
{
continue;
}
_zBuffer[x, y] = z;
// Pixel Shader
Color outputColor = InterpolateColor(
fa, triangle.Vertices[0].VertexColor,
fb, triangle.Vertices[1].VertexColor,
fc, triangle.Vertices[2].VertexColor);
if (TexturingEnabled && Material.DiffuseTexture != null)
{
var u = fa * triangle.Vertices[0].U + fb * triangle.Vertices[1].U + fc * triangle.Vertices[2].U;
var v = fa * triangle.Vertices[0].V + fb * triangle.Vertices[1].V + fc * triangle.Vertices[2].V;
u = Math.Min(Math.Max(u, 0.0), 1.0);
v = Math.Min(Math.Max(v, 0.0), 1.0);
Color texColor = Material.DiffuseTexture.GetPixel((int)(u * Material.DiffuseTexture.PixelWidth),
(int)(v * Material.DiffuseTexture.PixelHeight));
outputColor = MultiplyColors(outputColor, texColor);
}
// End of pixel shader
rt.SetPixel(x, y, outputColor);
}
}
activeEdges.ForEach(t => t.X += t.XSlope);
}
}