mirror of
https://github.com/thorvg/thorvg.git
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d71e11495d
The API allows now values <= 0 for dashes and gaps. Negative values are treated as zero. The exception is when all provided values are <= 0, in which case the dash is ignored. This fixes the issue when dash = 0 was provided for strokes with round or butt caps - the dot was not drawn, even though it should have been. docs: the strokeDash API behavior's clarification for odd numbers of values in dashPattern and refinement of the accepted values.
546 lines
No EOL
18 KiB
C++
546 lines
No EOL
18 KiB
C++
/*
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* Copyright (c) 2023 - 2025 the ThorVG project. All rights reserved.
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#ifndef _TVG_WG_GEOMETRY_H_
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#define _TVG_WG_GEOMETRY_H_
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#include <cassert>
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#include "tvgMath.h"
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#include "tvgRender.h"
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// default size of vertex and index buffers
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#define WG_DEFAULT_BUFFER_SIZE 2048
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struct WgVertexBuffer;
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struct WgIndexedVertexBuffer;
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struct WgGeometryBufferPool
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{
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private:
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Array<WgVertexBuffer*> vbuffers;
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Array<WgIndexedVertexBuffer*> ibuffers;
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public:
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~WgGeometryBufferPool();
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WgVertexBuffer* reqVertexBuffer(float scale = 1.0f);
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WgIndexedVertexBuffer* reqIndexedVertexBuffer(float scale = 1.0f);
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void retVertexBuffer(WgVertexBuffer* buffer);
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void retIndexedVertexBuffer(WgIndexedVertexBuffer* buffer);
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static WgGeometryBufferPool* instance(); //return the shared buffer pool
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};
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// simple vertex buffer
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struct WgVertexBuffer
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{
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Point* data; // vertex buffer
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struct Distance {
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float interval; // distance to previous point
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float length; // distance to the first point through all previous points
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} *dist;
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uint32_t count = 0;
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uint32_t reserved = WG_DEFAULT_BUFFER_SIZE;
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float scale; // tesselation scale
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bool closed = false;
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// callback for external process of polyline
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using onPolylineFn = std::function<void(const WgVertexBuffer& buff)>;
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WgVertexBuffer(float scale = 1.0f) : scale(scale)
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{
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data = tvg::malloc<Point*>(sizeof(Point) * reserved);
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dist = tvg::malloc<Distance*>(sizeof(Distance) * reserved);
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}
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~WgVertexBuffer()
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{
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tvg::free(data);
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tvg::free(dist);
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}
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// reset buffer
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void reset(float scale)
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{
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count = 0;
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closed = false;
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this->scale = scale;
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}
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// get the last point with optional index offset from the end
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Point last(size_t offset = 0) const
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{
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return data[count - offset - 1];
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}
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// get the last distance with optional index offset from the end
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float lastDist(size_t offset = 0) const
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{
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return dist[count - offset - 1].interval;
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}
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// get total length
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float total() const
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{
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return (count == 0) ? 0.0f : dist[count-1].length;
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}
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// get next vertex index by length using binary search
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size_t getIndexByLength(float len) const
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{
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if (count <= 1) return 0;
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size_t left = 0;
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size_t right = count - 1;
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while (left <= right) {
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size_t mid = left + (right - left) / 2;
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if (dist[mid].length == len) return mid;
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else if (dist[mid].length < len) left = mid + 1;
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else right = mid - 1;
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}
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return right + 1;
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}
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// get min and max values of the buffer
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void getMinMax(Point& pmin, Point& pmax) const
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{
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if (count == 0) return;
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pmax = pmin = data[0];
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for (size_t i = 1; i < count; i++) {
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pmin = min(pmin, data[i]);
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pmax = max(pmax, data[i]);
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}
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}
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// update points distancess to the prev point and total length
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void updateDistances()
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{
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if (count == 0) return;
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dist[0].interval = 0.0f;
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dist[0].length = 0.0f;
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for (size_t i = 1; i < count; i++) {
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dist[i].interval = tvg::length(data[i-1] - data[i]);
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dist[i].length = dist[i-1].length + dist[i].interval;
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}
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}
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// close vertex buffer
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void close()
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{
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// check if last point is not to close to the first point
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if (length(data[0] - last()) > 0.015625f) {
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append(data[0]);
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}
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closed = true;
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}
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// append point
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void append(const Point& p)
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{
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if (count >= reserved) {
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reserved *= 2;
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data = tvg::realloc<Point*>(data, reserved * sizeof(Point));
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dist = tvg::realloc<Distance*>(dist, reserved * sizeof(Distance));
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}
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data[count++] = p;
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}
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// append source vertex buffer in index range from start to end (end not included)
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void appendRange(const WgVertexBuffer& buff, size_t start_index, size_t end_index)
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{
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for (size_t i = start_index; i < end_index; i++) {
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append(buff.data[i]);
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}
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}
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// append circle (list of triangles)
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void appendCircle(float radius)
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{
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// get approx circle length
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float clen = 2.0f * radius * MATH_PI;
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size_t nsegs = std::max((uint32_t)(clen * scale / 8), 16U);
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// append circle^
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Point prev { std::sin(0.0f) * radius, std::cos(0.0f) * radius };
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for (size_t i = 1; i <= nsegs; i++) {
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float t = (2.0f * MATH_PI * i) / nsegs;
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Point curr { std::sin(t) * radius, std::cos(t) * radius };
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append(Point{0.0f, 0.0f});
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append(prev);
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append(curr);
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prev = curr;
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}
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}
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// append cubic spline
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void appendCubic(const Point& v0, const Point& v1, const Point& v2, const Point& v3)
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{
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// get approx cubic length
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float clen = (tvg::length(v0 - v1) + tvg::length(v1 - v2) + tvg::length(v2 - v3));
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size_t nsegs = std::max((uint32_t)(clen * scale / 16), 16U);
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// append cubic
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Bezier bezier{v0, v1, v2, v3};
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for (size_t i = 1; i <= nsegs; i++) {
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append(bezier.at((float)i / nsegs));
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}
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}
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// decode path with callback for external prcesses
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void decodePath(const RenderShape& rshape, bool update_dist, onPolylineFn onPolyline, bool trim = false)
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{
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// decode path
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reset(scale);
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PathCommand *cmds, *trimmedCmds = nullptr;
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Point *pts, *trimmedPts = nullptr;
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uint32_t cmdCnt{};
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if (trim) {
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RenderPath trimmedPath;
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if (!rshape.stroke->trim.trim(rshape.path, trimmedPath)) return;
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cmds = trimmedCmds = trimmedPath.cmds.data;
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cmdCnt = trimmedPath.cmds.count;
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pts = trimmedPts = trimmedPath.pts.data;
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trimmedPath.cmds.data = nullptr;
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trimmedPath.pts.data = nullptr;
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} else {
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cmds = rshape.path.cmds.data;
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cmdCnt = rshape.path.cmds.count;
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pts = rshape.path.pts.data;
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}
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size_t pntIndex = 0;
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for (uint32_t i = 0; i < cmdCnt; i++) {
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auto& cmd = cmds[i];
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if (cmd == PathCommand::MoveTo) {
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// after path decoding we need to update distances and total length
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if (update_dist) updateDistances();
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if ((onPolyline) && (count > 0)) onPolyline(*this);
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reset(scale);
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append(pts[pntIndex]);
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pntIndex++;
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} else if (cmd == PathCommand::LineTo) {
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append(pts[pntIndex]);
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pntIndex++;
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} else if (cmd == PathCommand::Close) {
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close();
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// proceed path if close command is not the last command and next command is LineTo or CubicTo
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if (i + 1 < cmdCnt && (cmds[i + 1] == PathCommand::LineTo || cmds[i + 1] == PathCommand::CubicTo)) {
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// proceed current path
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if (update_dist) updateDistances();
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if ((count > 0) && (onPolyline)) onPolyline(*this);
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// append closing point of current path as a first point of the new path
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Point last_pt = last();
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reset(scale);
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append(last_pt);
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}
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} else if (cmd == PathCommand::CubicTo) {
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// append tesselated cubic spline with scale param
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appendCubic(data[count - 1], pts[pntIndex + 0], pts[pntIndex + 1], pts[pntIndex + 2]);
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pntIndex += 3;
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}
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}
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tvg::free(trimmedCmds);
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tvg::free(trimmedPts);
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// after path decoding we need to update distances and total length
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if (update_dist) updateDistances();
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if ((count > 0) && (onPolyline)) onPolyline(*this);
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reset(scale);
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}
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};
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struct WgIndexedVertexBuffer
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{
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Point* vbuff;
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uint32_t* ibuff;
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uint32_t vcount = 0, icount = 0;
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size_t vreserved = WG_DEFAULT_BUFFER_SIZE;
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size_t ireserved = WG_DEFAULT_BUFFER_SIZE * 2;
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WgGeometryBufferPool* pool;
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WgVertexBuffer* dashed; // intermediate buffer for stroke dashing
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float scale;
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WgIndexedVertexBuffer(WgGeometryBufferPool* pool, float scale = 1.0f) : pool(pool), scale(scale)
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{
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vbuff = tvg::malloc<Point*>(sizeof(Point) * vreserved);
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ibuff = tvg::malloc<uint32_t*>(sizeof(uint32_t) * ireserved);
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dashed = pool->reqVertexBuffer();
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}
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~WgIndexedVertexBuffer()
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{
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pool->retVertexBuffer(dashed);
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tvg::free(vbuff);
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tvg::free(ibuff);
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}
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// reset buffer
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void reset(float scale)
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{
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icount = vcount = 0;
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this->scale = scale;
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}
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void growIndex(size_t grow)
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{
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if (icount + grow >= ireserved) {
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ireserved *= 2;
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ibuff = tvg::realloc<uint32_t*>(ibuff, ireserved * sizeof(uint32_t));
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}
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}
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void growVertex(size_t grow)
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{
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if (vcount + grow >= vreserved) {
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vreserved *= 2;
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vbuff = tvg::realloc<Point*>(vbuff, vreserved * sizeof(Point));
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}
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}
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// get min and max values of the buffer
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void getMinMax(Point& pmin, Point& pmax) const
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{
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if (vcount == 0) return;
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pmax = pmin = vbuff[0];
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for (size_t i = 1; i < vcount; i++) {
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pmin = min(pmin, vbuff[i]);
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pmax = max(pmax, vbuff[i]);
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}
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}
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// append quad - two triangles formed from four points
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void appendQuad(const Point& p0, const Point& p1, const Point& p2, const Point& p3)
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{
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growVertex(4);
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vbuff[vcount+0] = p0;
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vbuff[vcount+1] = p1;
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vbuff[vcount+2] = p2;
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vbuff[vcount+3] = p3;
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growIndex(6);
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ibuff[icount+0] = vcount + 0;
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ibuff[icount+1] = vcount + 1;
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ibuff[icount+2] = vcount + 2;
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ibuff[icount+3] = vcount + 1;
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ibuff[icount+4] = vcount + 3;
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ibuff[icount+5] = vcount + 2;
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vcount += 4;
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icount += 6;
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}
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void appendStrokesDashed(const WgVertexBuffer& buff, const RenderStroke* rstroke)
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{
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dashed->reset(scale);
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auto& dash = rstroke->dash;
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if (buff.count < 2) return;
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uint32_t index = 0;
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auto total = dash.pattern[index];
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auto length = (dash.count % 2) ? dash.length * 2 : dash.length;
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// normalize dash offset
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auto dashOffset = dash.offset;
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while(dashOffset < 0) dashOffset += length;
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while(dashOffset > length) dashOffset -= length;
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auto gap = false;
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// scip dashes by offset
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if (dashOffset > 0.0f) {
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while(total <= dashOffset) {
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index = (index + 1) % dash.count;
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total += dash.pattern[index];
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gap = !gap;
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}
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total -= dashOffset;
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}
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// iterate by polyline points
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for (uint32_t i = 0; i < buff.count - 1; i++) {
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if (!gap) dashed->append(buff.data[i]);
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// move inside polyline segment
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while(total < buff.dist[i+1].interval) {
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// get current point
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dashed->append(tvg::lerp(buff.data[i], buff.data[i+1], total / buff.dist[i+1].interval));
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// update current state
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index = (index + 1) % dash.count;
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total += dash.pattern[index];
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// preceed stroke if dash
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if (!gap) {
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dashed->updateDistances();
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appendStrokes(*dashed, rstroke);
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dashed->reset(scale);
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}
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gap = !gap;
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}
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// update current subline length
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total -= buff.dist[i+1].interval;
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}
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// draw last subline
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if (!gap) {
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dashed->append(buff.last());
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dashed->updateDistances();
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appendStrokes(*dashed, rstroke);
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}
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}
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// append buffer with optional offset
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void appendBuffer(const WgVertexBuffer& buff, Point offset = Point{0.0f, 0.0f})
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{
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growVertex(buff.count);
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growIndex(buff.count);
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for (uint32_t i = 0; i < buff.count; i++) {
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vbuff[vcount + i] = buff.data[i] + offset;
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ibuff[icount + i] = vcount + i;
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}
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vcount += buff.count;
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icount += buff.count;
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};
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void appendLine(const Point& v0, const Point& v1, float dist, float halfWidth)
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{
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if(tvg::zero(dist)) return;
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Point sub = v1 - v0;
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Point nrm = {sub.y / dist * halfWidth, -sub.x / dist * halfWidth};
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appendQuad(v0 - nrm, v0 + nrm, v1 - nrm, v1 + nrm);
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}
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void appendBevel(const Point& v0, const Point& v1, const Point& v2, float dist1, float dist2, float halfWidth)
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{
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if(tvg::zero(dist1) || tvg::zero(dist2)) return;
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Point sub1 = v1 - v0;
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Point sub2 = v2 - v1;
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Point nrm1 {sub1.y / dist1 * halfWidth, -sub1.x / dist1 * halfWidth};
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Point nrm2 {sub2.y / dist2 * halfWidth, -sub2.x / dist2 * halfWidth};
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appendQuad(v1 - nrm1, v1 + nrm1, v1 - nrm2, v1 + nrm2);
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}
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void appendMiter(const Point& v0, const Point& v1, const Point& v2, float dist1, float dist2, float halfWidth, float miterLimit)
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{
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if(tvg::zero(dist1) || tvg::zero(dist2)) return;
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auto sub1 = v1 - v0;
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auto sub2 = v2 - v1;
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auto nrm1 = Point{+sub1.y / dist1, -sub1.x / dist1};
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auto nrm2 = Point{+sub2.y / dist2, -sub2.x / dist2};
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auto offset1 = nrm1 * halfWidth;
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auto offset2 = nrm2 * halfWidth;
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auto nrm = nrm1 + nrm2;
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normalize(nrm);
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float cosine = dot(nrm, nrm1);
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if (tvg::zero(cosine)) return;
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float angle = std::acos(dot(nrm1, -nrm2));
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if (tvg::zero(angle) || tvg::equal(angle, MATH_PI)) return;
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float miterRatio = 1.0f / (std::sin(angle) * 0.5f);
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if (miterRatio <= miterLimit) {
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appendQuad(v1 + nrm * (halfWidth / cosine), v1 + offset2, v1 + offset1, v1);
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appendQuad(v1 - nrm * (halfWidth / cosine), v1 - offset2, v1 - offset1, v1);
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} else {
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appendQuad(v1 - offset1, v1 + offset2, v1 - offset2, v1 + offset1);
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}
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}
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void appendSquare(Point v0, Point v1, float dist, float halfWidth)
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{
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if(tvg::zero(dist)) {
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appendQuad(v1 + Point{-halfWidth, -halfWidth}, v1 + Point{-halfWidth, halfWidth}, v1 + Point{halfWidth, -halfWidth}, v1 + Point{halfWidth, halfWidth});
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return;
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}
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Point sub = v1 - v0;
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Point offset = sub / dist * halfWidth;
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Point nrm = {+offset.y, -offset.x};
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appendQuad(v1 - nrm, v1 + nrm, v1 + offset - nrm, v1 + offset + nrm);
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}
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void appendStrokes(const WgVertexBuffer& buff, const RenderStroke* rstroke)
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{
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assert(rstroke);
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// empty buffer gueard
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if (buff.count < 2) return;
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float halfWidth = rstroke->width * 0.5f;
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// append core lines
|
|
for (size_t i = 1; i < buff.count; i++) {
|
|
appendLine(buff.data[i-1], buff.data[i], buff.dist[i].interval, halfWidth);
|
|
}
|
|
|
|
// append caps (square)
|
|
if ((rstroke->cap == StrokeCap::Square) && !buff.closed) {
|
|
appendSquare(buff.data[1], buff.data[0], buff.dist[1].interval, halfWidth);
|
|
appendSquare(buff.last(1), buff.last(0), buff.lastDist(0), halfWidth);
|
|
}
|
|
|
|
// append round joints and caps
|
|
if ((rstroke->join == StrokeJoin::Round) || (rstroke->cap == StrokeCap::Round)) {
|
|
// create mesh for circle
|
|
WgVertexBuffer circle;
|
|
circle.reset(buff.scale);
|
|
circle.appendCircle(halfWidth);
|
|
// append caps (round)
|
|
if (rstroke->cap == StrokeCap::Round) {
|
|
appendBuffer(circle, buff.data[0]);
|
|
// append ending cap if polyline is not closed
|
|
if (!buff.closed) appendBuffer(circle, buff.last());
|
|
}
|
|
// append joints (round)
|
|
if (rstroke->join == StrokeJoin::Round) {
|
|
for (size_t i = 1; i < buff.count - 1; i++) {
|
|
appendBuffer(circle, buff.data[i]);
|
|
}
|
|
if (buff.closed) appendBuffer(circle, buff.last());
|
|
}
|
|
}
|
|
|
|
// append closed endings
|
|
if (buff.closed) {
|
|
// close by bevel
|
|
if (rstroke->join == StrokeJoin::Bevel) {
|
|
appendBevel(buff.last(1), buff.data[0], buff.data[1], buff.lastDist(0), buff.dist[1].interval, halfWidth);
|
|
// close by mitter
|
|
} else if (rstroke->join == StrokeJoin::Miter) {
|
|
appendMiter(buff.last(1), buff.data[0], buff.data[1], buff.lastDist(0), buff.dist[1].interval, halfWidth, rstroke->miterlimit);
|
|
}
|
|
}
|
|
|
|
// append joints (bevel)
|
|
if (rstroke->join == StrokeJoin::Bevel) {
|
|
for (size_t i = 1; i < buff.count - 1; i++) {
|
|
appendBevel(buff.data[i-1], buff.data[i], buff.data[i+1], buff.dist[i].interval, buff.dist[i+1].interval, halfWidth);
|
|
}
|
|
// append joints (mitter)
|
|
} else if (rstroke->join == StrokeJoin::Miter) {
|
|
for (size_t i = 1; i < buff.count - 1; i++) {
|
|
appendMiter(buff.data[i-1], buff.data[i], buff.data[i+1], buff.dist[i].interval, buff.dist[i+1].interval, halfWidth, rstroke->miterlimit);
|
|
}
|
|
}
|
|
}
|
|
};
|
|
|
|
#endif // _TVG_WG_GEOMETRY_H_
|