public IntersectionResult Intersect(Ray r)
{
Vector3 p2p1 = p2 - p1;
Vector3 p3p1 = p3 - p1;
Vector3 triNormal = Vector3.Cross(p2p1, p3p1);
triNormal.Normalize();
float dot = Vector3.Dot(r.Direction, triNormal);
if (Calc.AlmostZero(dot))
return IntersectionResult.NoIntersection;
else
{
float d = Vector3.Dot(triNormal, p1);
float np4 = Vector3.Dot(triNormal, r.Origin);
float nv = Vector3.Dot(triNormal, r.Direction);
float t = (d - np4) / nv;
Vector3 q = r.Origin + r.Direction * t;
float a = Vector3.Dot(Vector3.Cross(p2p1, q - p1), triNormal);
float b = Vector3.Dot(Vector3.Cross(p3 - p2, q - p2), triNormal);
float c = Vector3.Dot(Vector3.Cross(p1 - p3, q - p3), triNormal);
if (a >= 0 && b >= 0 && c >= 0)
return IntersectionResult.Interects(t);
else
return IntersectionResult.NoIntersection;
}
}
private void button1_Click(object sender, EventArgs e)
{
using (Graphics g = CreateGraphics())
{
Triangle tri = new Triangle(v(0, 0, 0), v(100, 0, 0), v(0, 100, 0));
for(int x=0; x<Width; x++)
for (int y = 0; y < Height; y++)
{
Ray r = new Ray(v(x, y, 100), v(0, 0, -1));
if (tri.Intersect(r).DoesIntersect)
g.FillRectangle(new SolidBrush(Color.Red), new Rectangle(x, y, 1, 1));
}
}
}
public static void SelfTest(ITestToolkit tk)
{
Triangle t = new Triangle(Vector3.UnitX, Vector3.UnitY, Vector3.UnitZ);
Ray r = new Ray(new Vector3(0.1f, 0.1f, 3), new Vector3(0, 0, -1));
IntersectionResult result = t.Intersect(r);
tk.Assert(result.DoesIntersect);
t = new Triangle(Vector3.Zero, Vector3.UnitX, Vector3.UnitY);
r = new Ray(new Vector3(0.1f, 0.1f, 3), -Vector3.UnitZ);
result = t.Intersect(r);
tk.AssertEqual(3, result.Param);
r = new Ray(new Vector3(-1, 0, 3), -Vector3.UnitZ);
result = t.Intersect(r);
tk.Assert(!result.DoesIntersect);
}
public static void SelfTest(ITestToolkit tk)
{
Ray r = new Ray(Vector3.UnitX, Vector3.UnitX);
Vector3 origin = r.Origin;
Vector3 dir = r.Direction;
}