public static Triangle[] SliceTri(Triangle source, Vector2 lineStart, Vector2 lineEnd)
{
Triangle[] output = new Triangle[3];
for (int i = 0; i < 3; i++)
{
output[i] = new Triangle();
}
Vector2 soloPoint;
Vector2 soloUV;
float soloY;
Vector2 pairPoint0;
Vector2 pairPoint1;
Vector2 pairUV0;
Vector2 pairUV1;
float pairY0;
float pairY1;
bool sign0 = MathsHelper.sign(source.p0, lineStart, lineEnd) <= 0.0f;
bool sign1 = MathsHelper.sign(source.p1, lineStart, lineEnd) <= 0.0f;
bool sign2 = MathsHelper.sign(source.p2, lineStart, lineEnd) <= 0.0f;
if (sign0 == sign1)
{
soloPoint = source.p2;
pairPoint0 = source.p0;
pairPoint1 = source.p1;
soloUV = source.uv2;
pairUV0 = source.uv0;
pairUV1 = source.uv1;
soloY = source.y2;
pairY0 = source.y0;
pairY1 = source.y1;
}
else if (sign1 == sign2)
{
soloPoint = source.p0;
pairPoint0 = source.p1;
pairPoint1 = source.p2;
soloUV = source.uv0;
pairUV0 = source.uv1;
pairUV1 = source.uv2;
soloY = source.y0;
pairY0 = source.y1;
pairY1 = source.y2;
}
else
{
soloPoint = source.p1;
pairPoint0 = source.p0;
pairPoint1 = source.p2;
soloUV = source.uv1;
pairUV0 = source.uv0;
pairUV1 = source.uv2;
soloY = source.y1;
pairY0 = source.y0;
pairY1 = source.y2;
}
// Right, so we know which verts are on which side of the slice-line. Time for the intersections.
Vector2 intersection0, intersection1;
MathsHelper.LineIntersectionPoint(lineStart, lineEnd, pairPoint0, soloPoint, out intersection0);
MathsHelper.LineIntersectionPoint(lineStart, lineEnd, pairPoint1, soloPoint, out intersection1);
// Lerp dem UVs
float lerpDistance0 = (intersection0 - pairPoint0).magnitude / (soloPoint - pairPoint0).magnitude;
float lerpDistance1 = (intersection1 - pairPoint1).magnitude / (soloPoint - pairPoint1).magnitude;
Vector2 intersectionUV0 = pairUV0 + (soloUV - pairUV0) * lerpDistance0;
Vector2 intersectionUV1 = pairUV1 + (soloUV - pairUV1) * lerpDistance1;
float intersectionY0 = pairY0 + (soloY - pairY0) * lerpDistance0;
float intersectionY1 = pairY1 + (soloY - pairY1) * lerpDistance1;
// Three triangles. One for the isolated tri, two for the trapezoid base.
output[0].p0 = soloPoint;
output[0].p1 = intersection1;
output[0].p2 = intersection0;
output[0].uv0 = soloUV;
output[0].uv1 = intersectionUV1;
output[0].uv2 = intersectionUV0;
output[0].y0 = soloY;
output[0].y1 = intersectionY1;
output[0].y2 = intersectionY0;
output[1].p0 = pairPoint0;
output[1].p1 = intersection0;
output[1].p2 = pairPoint1;
output[1].uv0 = pairUV0;
output[1].uv1 = intersectionUV0;
output[1].uv2 = pairUV1;
output[1].y0 = pairY0;
output[1].y1 = intersectionY0;
output[1].y2 = pairY1;
output[2].p0 = pairPoint1;
output[2].p1 = intersection0;
output[2].p2 = intersection1;
output[2].uv0 = pairUV1;
output[2].uv1 = intersectionUV0;
output[2].uv2 = intersectionUV1;
output[2].y0 = pairY1;
output[2].y1 = intersectionY0;
output[2].y2 = intersectionY1;
return(output);
}
