//////////////////
// GradientLayerMesh
GradientLayerMesh::GradientLayerMesh(const Rect &rect,Vec2 axisStart,Vec2 axisEnd,const Gradient *gradient)
{
ConvexPolygon rectPol =
{
rect.GetCorner(0),
rect.GetCorner(2),
rect.GetCorner(3),
rect.GetCorner(1),
};
std::vector<float> slicePositions;
for(int i = 0;i < gradient->GetNumVertices();i++)
{
slicePositions.push_back(gradient->GetVertexPos(i));
}
Vec2 axis = axisEnd - axisStart;
axis /= axis.GetSqrLen();
float axisOffset = -Dot(axis,axisStart);
std::vector<ParallelSlice> slices = rectPol.GetParallelSlices(
axisStart,axisEnd,slicePositions.data(),(int)slicePositions.size());
for(const ParallelSlice &slice : slices)
{
int seg = slice.GetSegment();
if(seg == 0)
{
std::vector<Triangle2D> tris = slice.GetPolygon().Triangulate();
for(const Triangle2D &tri : tris)
{
mVertices.push_back(tri.mVertices[0]);
mVertices.push_back(tri.mVertices[1]);
mVertices.push_back(tri.mVertices[2]);
mColors.push_back(MakeVec4(1,0,0,1));
mColors.push_back(MakeVec4(0,1,0,1));
mColors.push_back(MakeVec4(0,0,1,1));
}
}
else if(seg == gradient->GetNumVertices())
{
std::vector<Triangle2D> tris = slice.GetPolygon().Triangulate();
for(const Triangle2D &tri : tris)
{
mVertices.push_back(tri.mVertices[0]);
mVertices.push_back(tri.mVertices[1]);
mVertices.push_back(tri.mVertices[2]);
mColors.push_back(MakeVec4(1,0,0,1));
mColors.push_back(MakeVec4(0,1,0,1));
mColors.push_back(MakeVec4(0,0,1,1));
}
}
else
{
std::vector<Triangle2D> tris = slice.GetPolygon().Triangulate();
for(const Triangle2D &tri : tris)
{
for(int i = 0;i < 3;i++)
{
mVertices.push_back(tri.mVertices[i]);
float t = Dot(axis,tri.mVertices[i]) + axisOffset;
float segT = (t - slicePositions[seg - 1]) / (slicePositions[seg] - slicePositions[seg - 1]);
Vec4 color = gradient->GetVertexColor(seg - 1) * (1 - segT) + gradient->GetVertexColor(seg) * segT;
mColors.push_back(color);
}
}
}
}
}
std::vector<ParallelSlice> ConvexPolygon::GetParallelSlices(const Vec2 &min,const Vec2 &max,
const float *slicePositions,int numSlicePositions) const
{
int numVerts = GetNumVertices();
const Vec2 *vertices = GetVertices();
assert((max - min).GetSqrLen() > .001f);
assert(std::is_sorted(slicePositions,slicePositions + numSlicePositions));
Vec2 axis = max - min;
axis /= axis.GetSqrLen();
float axisOrigin = Dot(axis,min);
std::vector<float> vertOnAxis(numVerts);
for(int i = 0;i < numVerts;i++)
vertOnAxis[i] = Dot(axis,vertices[i]) - axisOrigin;
int minVert = (int)(std::min_element(vertOnAxis.begin(),vertOnAxis.end()) - vertOnAxis.begin());
int maxVert = (int)(std::max_element(vertOnAxis.begin(),vertOnAxis.end()) - vertOnAxis.begin());
#ifndef NDEBUG
for(int i = 0;i < numVerts;i++)
{
assert(vertOnAxis[i] >= vertOnAxis[minVert]);
assert(vertOnAxis[i] <= vertOnAxis[maxVert]);
}
#endif
// Segments are indexed so that their index matches the index of the high slice.
// minSeg and maxSeg describes the range [minSeg,maxSeg] of intervals which contain a part
// of the polygon in their interior. minSeg is thus the index of the first slicePosition
// that is strictly greater than minPos, and maxSeg the index of the first slicePosition
// that is greater than or equal to maxPos
int minSeg = numSlicePositions;
int maxSeg = numSlicePositions;
for(int i = 0;i < numSlicePositions;i++)
{
if(vertOnAxis[minVert] < slicePositions[i])
{
minSeg = i;
break;
}
}
for(int i = minSeg;i < numSlicePositions;i++)
{
if(vertOnAxis[maxVert] <= slicePositions[i])
{
maxSeg = i;
break;
}
}
assert(minSeg == 0 || vertOnAxis[minVert] >= slicePositions[minSeg - 1]);
assert(minSeg == numSlicePositions || vertOnAxis[minVert] < slicePositions[minSeg]);
assert(maxSeg == 0 || vertOnAxis[maxVert] > slicePositions[maxSeg - 1]);
assert(maxSeg == numSlicePositions || vertOnAxis[maxVert] <= slicePositions[maxSeg]);
// index of the vertex at the beginning of the current counter clockwise/clockwise edge respectively.
int ccwPrevVert = minVert;
int cwPrevVert = minVert;
// index of the vertex at the end of the current counter clockwise/clockwise edge respectively.
int ccwVert = (minVert + 1) % numVerts;
int cwVert = (minVert - 1 + numVerts) % numVerts;
std::vector<ParallelSlice> ret;
std::vector<Vec2> nextPol;
nextPol.push_back(vertices[minVert]);
for(int seg = minSeg;seg < maxSeg;seg++)
{
std::vector<Vec2> curPol;
curPol.swap(nextPol);
while(true)
{
float curPos = vertOnAxis[ccwVert];
if(curPos < slicePositions[seg])
{
curPol.push_back(vertices[ccwVert]);
ccwPrevVert = ccwVert;
ccwVert = (ccwVert + 1) % numVerts;
}
else if(curPos > slicePositions[seg])
{
float prevPos = vertOnAxis[ccwPrevVert];
float t = (slicePositions[seg] - prevPos) / (curPos - prevPos);
Vec2 newVert = vertices[ccwPrevVert] + t * (vertices[ccwVert] - vertices[ccwPrevVert]);
curPol.push_back(newVert);
nextPol.push_back(newVert);
break;
}
else //if(pos == slicePositions[seg])
{
curPol.push_back(vertices[ccwVert]);
nextPol.push_back(vertices[ccwVert]);
ccwPrevVert = ccwVert;
ccwVert = (ccwVert + 1) % numVerts;
break;
}
}
int firstClockWise = (int)curPol.size();
while(true)
{
float curPos = vertOnAxis[cwVert];
if(curPos < slicePositions[seg])
{
curPol.push_back(vertices[cwVert]);
cwPrevVert = cwVert;
cwVert = (cwVert + numVerts - 1) % numVerts;
}
else if(curPos > slicePositions[seg])
{
float prevPos = vertOnAxis[cwPrevVert];
float t = (slicePositions[seg] - prevPos) / (curPos - prevPos);
Vec2 newVert = vertices[cwPrevVert] + t * (vertices[cwVert] - vertices[cwPrevVert]);
curPol.push_back(newVert);
nextPol.push_back(newVert);
break;
}
else //if(pos == slicePositions[seg])
{
curPol.push_back(vertices[cwVert]);
nextPol.push_back(vertices[cwVert]);
cwPrevVert = cwVert;
cwVert = (cwVert + numVerts - 1) % numVerts;
break;
}
}
std::reverse(curPol.begin() + firstClockWise,curPol.end());
std::reverse(nextPol.begin(), nextPol.end());
ret.push_back(ParallelSlice(ConvexPolygon(curPol),seg));
}
// special case for the last segment, where, among other things, we may not
// have a value for slicePositions[seg] (may be outside its bounds).
{
std::vector<Vec2> lastPol = nextPol;
while(ccwVert != cwVert)
{
lastPol.push_back(vertices[ccwVert]);
ccwVert = (ccwVert + 1) % numVerts;
}
lastPol.push_back(vertices[cwVert]);
ret.push_back(ParallelSlice(ConvexPolygon(lastPol),maxSeg));
}
return ret;
}
