#include "Macro.hpp" #include "DrawOpQueue.hpp" #include #include #include #include struct Gosu::Macro::Impl { typedef double Float; VertexArrays vertexArrays; int width, height; Transform findTransformForTarget(Float x1, Float y1, Float x2, Float y2, Float x3, Float y3, Float x4, Float y4) const { // Transformation logic follows a discussion on the ImageMagick mailing // list (on which ImageMagick's perspective_transform.pl is based). // To draw a macro at an arbitrary position, we solve the following system: // 0, 0, 1, 0, 0, 0, 0, 0 | x1 // 0, 0, 0, 0, 0, 1, 0, 0 | y1 // w, 0, 1, 0, 0, 0, -x2w, 0 | x2 // 0, 0, 0, w, 0, 1, -y2w, 0 | y2 // 0, h, 1, 0, 0, 0, 0, -x3h | x3 // 0, 0, 0, 0, h, 1, 0, -y3h | y3 // w, h, 1, 0, 0, 0, -x4w, -x4h | x4 // 0, 0, 0, w, h, 1, -y4w, -y4h | y4 // Equivalent: // 0, 0, 1, 0, 0, 0, 0, 0 | x1 // 0, 0, 0, 0, 0, 1, 0, 0 | y1 // w, 0, 0, 0, 0, 0, -x2w, 0 | x2-x1 // 0, 0, 0, w, 0, 0, -y2w, 0 | y2-y1 // 0, h, 0, 0, 0, 0, 0, -x3h | x3-x1 // 0, 0, 0, 0, h, 0, 0, -y3h | y3-y1 // 0, 0, 0, 0, 0, 0, (x2-x4)w, (x3-x4)h | x1-x2-x3+x4 // 0, 0, 0, 0, 0, 0, (y2-y4)w, (y3-y4)h | y1-y2-y3+y4 // Since this matrix is relatively sparse, we unroll all three solving paths. static const Transform nullTransform = {{ 0 }}; // Row 7 is completely useless if (x2 == x4 && x3 == x4) return nullTransform; // Row 8 is completely useless if (y2 == y3 && y3 == y4) return nullTransform; // Col 7 is completely useless if (x2 == x4 && y2 == y4) return nullTransform; // Col 8 is completely useless if (x3 == x4 && y3 == y4) return nullTransform; Float c[8]; // Rows 1, 2 c[2] = x1, c[5] = y1; // The logic below assumes x2 != x4, i.e. row7 can be used to eliminate // the leftmost value in row 8 and afterwards the values in rows 3 & 4. // If x2 == x4, we need to exchange rows 7 and 8. // TODO: x2==x4 is the normal case where an image is // drawn upright; the code should rather swap in the rare case that x3==x4! Float leftCell7 = (x2-x4)*width, rightCell7 = (x3-x4)*height, origRightSide7 = (x1-x2-x3+x4); Float leftCell8 = (y2-y4)*width, rightCell8 = (y3-y4)*height, origRightSide8 = (y1-y2-y3+y4); bool swapRows78 = x2 == x4; if (swapRows78) { std::swap(leftCell7, leftCell8); std::swap(rightCell7, rightCell8); std::swap(origRightSide7, origRightSide8); } // 0, 0, 1, 0, 0, 0, 0, 0 | x1 // 0, 0, 0, 0, 0, 1, 0, 0 | y1 // w, 0, 0, 0, 0, 0, -x2w, 0 | x2-x1 // 0, 0, 0, w, 0, 0, -y2w, 0 | y2-y1 // 0, h, 0, 0, 0, 0, 0, -x3h | x3-x1 // 0, 0, 0, 0, h, 0, 0, -y3h | y3-y1 // 0, 0, 0, 0, 0, 0, leftCell7, rightCell7 | origRightSide7 // 0, 0, 0, 0, 0, 0, leftCell8, rightCell8 | origRightSide8 // Use row 7 to eliminate the left cell in row 8 // Row8 = Row8 - factor78 * Row7 Float factor78 = leftCell8 / leftCell7; Float remCell8 = rightCell8 - rightCell7 * factor78; Float rightSide8 = origRightSide8 - origRightSide7 * factor78; c[7] = rightSide8 / remCell8; // 0, 0, 1, 0, 0, 0, 0, 0 | x1 // 0, 0, 0, 0, 0, 1, 0, 0 | y1 // w, 0, 0, 0, 0, 0, -x2w, 0 | x2-x1 // 0, 0, 0, w, 0, 0, -y2w, 0 | y2-y1 // 0, h, 0, 0, 0, 0, 0, -x3h | x3-x1 // 0, 0, 0, 0, h, 0, 0, -y3h | y3-y1 // 0, 0, 0, 0, 0, 0, leftCell7, rightCell7 | origRightSide7 // 0, 0, 0, 0, 0, 0, 0, remCell8 | rightSide8 // Use the remaining value in row 8 to eliminate the right value in row 7. // Row7 = Row7 - factor87 * Row8 Float factor87 = rightCell7 / remCell8; Float remCell7 = leftCell7; Float rightSide7 = origRightSide7 - rightSide8 * factor87; c[6] = rightSide7 / remCell7; // 0, 0, 1, 0, 0, 0, 0, 0 | x1 // 0, 0, 0, 0, 0, 1, 0, 0 | y1 // w, 0, 0, 0, 0, 0, -x2w, 0 | x2-x1 // 0, 0, 0, w, 0, 0, -y2w, 0 | y2-y1 // 0, h, 0, 0, 0, 0, 0, -x3h | x3-x1 // 0, 0, 0, 0, h, 0, 0, -y3h | y3-y1 // 0, 0, 0, 0, 0, 0, remCell7, 0 | rightSide7 // 0, 0, 0, 0, 0, 0, 0, remCell8 | rightSide8 // Use the new rows 7 and 8 to calculate c0, c1, c3 & c4. // Row3 = Row3 - factor73 * Row7 Float factor73 = -x2*width / remCell7; Float remCell3 = width; Float rightSide3 = (x2-x1) - rightSide7 * factor73; c[0] = rightSide3 / remCell3; // Row4 = Row4 - factor74 * Row7 Float factor74 = -y2*width / remCell7; Float remCell4 = width; Float rightSide4 = (y2-y1) - rightSide7 * factor74; c[3] = rightSide4 / remCell4; // Row5 = Row5 - factor85 * Row7 Float factor85 = -x3*height / remCell8; Float remCell5 = height; Float rightSide5 = (x3-x1) - rightSide8 * factor85; c[1] = rightSide5 / remCell5; // Row6 = Row6 - factor86 * Row8 Float factor86 = -y3*height / remCell8; Float remCell6 = height; Float rightSide6 = (y3-y1) - rightSide8 * factor86; c[4] = rightSide6 / remCell6; if (swapRows78) std::swap(c[6], c[7]); // Let's hope I never have to debug/understand this again! :D Transform result = {{ c[0], c[3], 0, c[6], c[1], c[4], 0, c[7], 0, 0, 1, 0, c[2], c[5], 0, 1 }}; return result; } void drawVertexArrays(Float x1, Float y1, Float x2, Float y2, Float x3, Float y3, Float x4, Float y4) const { // TODO: Macros should not be split up just because they have different transforms! This is insane. // They should be premultiplied and have the same transform by definition. Then the transformation // only has to be performed once. #ifndef GOSU_IS_OPENGLES glEnable(GL_BLEND); glMatrixMode(GL_MODELVIEW); Transform transform = findTransformForTarget(x1, y1, x2, y2, x3, y3, x4, y4); for (VertexArrays::const_iterator it = vertexArrays.begin(), end = vertexArrays.end(); it != end; ++it) { glPushMatrix(); it->renderState.apply(); glMultMatrixd(&transform[0]); glInterleavedArrays(GL_T2F_C4UB_V3F, 0, &it->vertices[0]); glDrawArrays(GL_QUADS, 0, (GLsizei)it->vertices.size()); glPopMatrix(); } #endif } }; Gosu::Macro::Macro(DrawOpQueue& queue, int width, int height) : pimpl(new Impl) { pimpl->width = width; pimpl->height = height; queue.compileTo(pimpl->vertexArrays); } int Gosu::Macro::width() const { return pimpl->width; } int Gosu::Macro::height() const { return pimpl->height; } void Gosu::Macro::draw(double x1, double y1, Color c1, double x2, double y2, Color c2, double x3, double y3, Color c3, double x4, double y4, Color c4, ZPos z, AlphaMode mode) const { if (c1 != Color::WHITE || c2 != Color::WHITE || c3 != Color::WHITE || c4 != Color::WHITE) throw std::invalid_argument("Macros cannot be tinted with colors yet"); std::tr1::function f = std::tr1::bind(&Impl::drawVertexArrays, pimpl, x1, y1, x2, y2, x3, y3, x4, y4); Gosu::Graphics::scheduleGL(f, z); } const Gosu::GLTexInfo* Gosu::Macro::glTexInfo() const { return 0; } Gosu::Bitmap Gosu::Macro::toBitmap() const { throw std::logic_error("Gosu::Macro cannot be rendered as Gosu::Bitmap yet"); } GOSU_UNIQUE_PTR Gosu::Macro::subimage(int x, int y, int width, int height) const { return GOSU_UNIQUE_PTR(); } void Gosu::Macro::insert(const Bitmap& bitmap, int x, int y) { throw std::logic_error("Gosu::Macro cannot be updated with a Gosu::Bitmap yet"); }