void AreaShader::shadeArea(Surface& s, const Area* ar) const { WFMath::Polygon<2> clipped = ar->clipToSegment(s.m_segment); assert(clipped.isValid()); if (clipped.numCorners() == 0) return; Point2 segOrigin = s.m_segment.getRect().lowCorner(); clipped.shift(Point2(0,0) - segOrigin); scanConvert(clipped, s); }
static void scanConvert(const WFMath::Polygon<2>& inPoly, Surface& sf) { if (!inPoly.isValid()) return; std::list<Edge> pending; std::vector<Edge> active; Point2 lastPt = inPoly.getCorner(inPoly.numCorners() - 1); for (std::size_t p=0; p < inPoly.numCorners(); ++p) { Point2 curPt = inPoly.getCorner(p); // skip horizontal edges if (curPt.y() != lastPt.y()) pending.emplace_back(lastPt, curPt); lastPt = curPt; } if (pending.empty()) return; // sort edges by starting (lowest) z value pending.sort(); active.push_back(pending.front()); pending.pop_front(); // advance to the row of the first z value, and ensure z sits in the // middle of sample rows - we do this by offseting by 1/2 a row height // if you don't do this, you'll find alternating rows are over/under // sampled, producing a charming striped effect. WFMath::CoordType z = std::floor(active.front().start().y()) + ROW_HEIGHT * 0.5f; for (; !pending.empty() || !active.empty(); z += ROW_HEIGHT) { while (!pending.empty() && (pending.front().start().y() <= z)) { active.push_back(pending.front()); pending.pop_front(); } // sort by x value - note active will be close to sorted anyway std::sort(active.begin(), active.end(), EdgeAtZ(z)); // delete finished edges for (unsigned int i=0; i< active.size(); ) { if (active[i].end().y() <= z) active.erase(active.begin() + i); else ++i; } // draw pairs of active edges for (unsigned int i=1; i < active.size(); i += 2) span(sf, z, active[i - 1].xValueAtZ(z), active[i].xValueAtZ(z)); } // of active edges loop }
WFMath::Polygon<2> sutherlandHodgmanKernel(const WFMath::Polygon<2>& inpoly, Clip clipper) { WFMath::Polygon<2> outpoly; if (!inpoly.isValid()) return inpoly; std::size_t points = inpoly.numCorners(); if (points < 3) return outpoly; // i.e an invalid result Point2 lastPt = inpoly.getCorner(points - 1); bool lastInside = clipper.inside(lastPt); for (std::size_t p = 0; p < points; ++p) { Point2 curPt = inpoly.getCorner(p); bool inside = clipper.inside(curPt); if (lastInside) { if (inside) { // emit curPt outpoly.addCorner(outpoly.numCorners(), curPt); } else { // emit intersection of edge with clip line outpoly.addCorner(outpoly.numCorners(), clipper.clip(lastPt, curPt)); } } else { if (inside) { // emit both outpoly.addCorner(outpoly.numCorners(), clipper.clip(lastPt, curPt)); outpoly.addCorner(outpoly.numCorners(), curPt); } else { // don't emit anything } } // last was outside lastPt = curPt; lastInside = inside; } return outpoly; }
void Area::setShape(const WFMath::Polygon<2>& p) { assert(p.isValid()); m_shape = p; m_box = p.boundingBox(); }
int main(int argc, char* argv[]) { Mercator::Area* a1 = new Mercator::Area(1, false); WFMath::Polygon<2> p; p.addCorner(p.numCorners(), Point2(3, 4)); p.addCorner(p.numCorners(), Point2(10, 10)); p.addCorner(p.numCorners(), Point2(-1, 18)); p.addCorner(p.numCorners(), Point2(-8, 11)); a1->setShape(p); Mercator::Terrain terrain(Mercator::Terrain::SHADED, seg_size); Mercator::AreaShader* ashade = new Mercator::AreaShader(1); terrain.addShader(ashade, 0); terrain.setBasePoint(-2, -1, 5); terrain.setBasePoint(-2, 0, 2); terrain.setBasePoint(-2, 1, 19); terrain.setBasePoint(-1, -1, 4); terrain.setBasePoint(-1, 0, 6); terrain.setBasePoint(-1, 1, 10); terrain.setBasePoint(0, -1, 2); terrain.setBasePoint(0, 0, -1); terrain.setBasePoint(0, 1, 8); terrain.setBasePoint(0, 2, 11); terrain.setBasePoint(1, -1, 7); terrain.setBasePoint(1, 0, 2); terrain.setBasePoint(1, 1, 11); terrain.setBasePoint(1, 2, 9); terrain.setBasePoint(2, -1, 3); terrain.setBasePoint(2, 0, 8); terrain.setBasePoint(2, 1, 2); terrain.setBasePoint(3, -1, 6); terrain.setBasePoint(3, 0, 7); terrain.setBasePoint(3, 1, 9); terrain.addArea(a1); Mercator::Segment* seg = terrain.getSegment(0,0); assert(seg->getAreas().size() == 1); assert(seg->getAreas().count(1) == 1); assert(a1->checkIntersects(*seg)); seg = terrain.getSegment(1,0); assert(seg->getAreas().size() == 0); assert(seg->getAreas().count(1) == 0); assert(a1->checkIntersects(*seg) == false); WFMath::Polygon<2> clipped = a1->clipToSegment(*seg); assert(clipped.isValid()); seg = terrain.getSegment(-1,0); assert(seg->getAreas().size() == 1); assert(seg->getAreas().count(1) == 1); assert(a1->checkIntersects(*seg)); clipped = a1->clipToSegment(*seg); assert(clipped.isValid()); seg = terrain.getSegment(0,1); assert(seg->getAreas().size() == 1); assert(seg->getAreas().count(1) == 1); assert(a1->checkIntersects(*seg)); clipped = a1->clipToSegment(*seg); assert(clipped.isValid()); seg = terrain.getSegment(2,0); assert(seg->getAreas().size() == 0); assert(seg->getAreas().count(1) == 0); assert(a1->checkIntersects(*seg) == false); p.clear(); p.addCorner(p.numCorners(), Point2(3 + seg_size, 4)); p.addCorner(p.numCorners(), Point2(10 + seg_size, 10)); p.addCorner(p.numCorners(), Point2(-1 + seg_size, 18)); p.addCorner(p.numCorners(), Point2(-8 + seg_size, 11)); a1->setShape(p); terrain.updateArea(a1); seg = terrain.getSegment(0,0); assert(seg->getAreas().size() == 1); assert(seg->getAreas().count(1) == 1); assert(a1->checkIntersects(*seg)); seg = terrain.getSegment(1,0); assert(seg->getAreas().size() == 1); assert(seg->getAreas().count(1) == 1); assert(a1->checkIntersects(*seg)); clipped = a1->clipToSegment(*seg); assert(clipped.isValid()); seg = terrain.getSegment(-1,0); assert(seg->getAreas().size() == 0); assert(seg->getAreas().count(1) == 0); assert(a1->checkIntersects(*seg) == false); seg = terrain.getSegment(0,1); assert(seg->getAreas().size() == 1); assert(seg->getAreas().count(1) == 1); assert(a1->checkIntersects(*seg)); clipped = a1->clipToSegment(*seg); assert(clipped.isValid()); seg = terrain.getSegment(2,0); assert(seg->getAreas().size() == 0); assert(seg->getAreas().count(1) == 0); assert(a1->checkIntersects(*seg) == false); clipped = a1->clipToSegment(*seg); assert(clipped.isValid()); terrain.removeArea(a1); seg = terrain.getSegment(0,0); assert(seg->getAreas().size() == 0); assert(seg->getAreas().count(1) == 0); seg = terrain.getSegment(1,0); assert(seg->getAreas().size() == 0); assert(seg->getAreas().count(1) == 0); seg = terrain.getSegment(-1,0); assert(seg->getAreas().size() == 0); assert(seg->getAreas().count(1) == 0); seg = terrain.getSegment(0,1); assert(seg->getAreas().size() == 0); assert(seg->getAreas().count(1) == 0); testAreaShader(); testAddToSegment(); return EXIT_SUCCESS; }