Implement chart pack algorithm

Chart pack algorithm: We guess a initial texture size based on the sum of chart areas, and try different methods then pick a best one, if pack failed because of texture size, we grow the size until it fit.

simpleuv.pro

@@ -4,17 +4,24 @@ CONFIG += release
 DEFINES += NDEBUG
 
 INCLUDEPATH += ./
-INCLUDEPATH += ./thirdparty/libigl/include
-INCLUDEPATH += ./thirdparty/eigen
+INCLUDEPATH += thirdparty/libigl/include
+INCLUDEPATH += thirdparty/eigen
+INCLUDEPATH += thirdparty/squeezer
 
 SOURCES += simpleuv/parametrize.cpp
 HEADERS += simpleuv/parametrize.h
 
 SOURCES += simpleuv/uvunwrapper.cpp
 HEADERS += simpleuv/uvunwrapper.h
 
+SOURCES += simpleuv/chartpacker.cpp
+HEADERS += simpleuv/chartpacker.h
+
 HEADERS += simpleuv/meshdatatype.h
 
+SOURCES += thirdparty/squeezer/maxrects.c
+HEADERS += thirdparty/squeezer/maxrects.h
+
 QMAKE_CXXFLAGS += -std=c++11
 
 target.path = ./

simpleuv/chartpacker.cpp

@@ -0,0 +1,82 @@
+#include <simpleuv/chartpacker.h>
+#include <cmath>
+extern "C" {
+#include <maxrects.h>
+}
+
+namespace simpleuv
+{
+
+void ChartPacker::setCharts(const std::vector<std::pair<float, float>> &chartSizes)
+{
+    m_chartSizes = chartSizes;
+}
+
+const std::vector<std::tuple<float, float, float, float, bool>> &ChartPacker::getResult()
+{
+    return m_result;
+}
+
+double ChartPacker::calculateTotalArea()
+{
+    double totalArea = 0;
+    for (const auto &chartSize: m_chartSizes) {
+        totalArea += chartSize.first * chartSize.second;
+    }
+    return totalArea;
+}
+
+bool ChartPacker::tryPack(float textureSize)
+{
+    std::vector<maxRectsSize> rects;
+    int width = textureSize * m_floatToIntFactor;
+    int height = width;
+    for (const auto &chartSize: m_chartSizes) {
+        maxRectsSize r;
+        r.width = chartSize.first * m_floatToIntFactor;
+        r.height = chartSize.second * m_floatToIntFactor;
+        rects.push_back(r);
+    }
+    const maxRectsFreeRectChoiceHeuristic methods[] = {
+        rectBestShortSideFit,
+        rectBestLongSideFit,
+        rectBestAreaFit,
+        rectBottomLeftRule,
+        rectContactPointRule
+    };
+    float occupancy = 0;
+    float bestOccupancy = 0;
+    std::vector<maxRectsPosition> bestResult;
+    for (size_t i = 0; i < sizeof(methods) / sizeof(methods[0]); ++i) {
+        std::vector<maxRectsPosition> result(rects.size());
+        if (!maxRects(width, height, rects.size(), rects.data(), methods[i], true, result.data(), &occupancy)) {
+            continue;
+        }
+        if (occupancy >= bestOccupancy) {
+            bestResult = result;
+            bestOccupancy = occupancy;
+        }
+    }
+    if (bestResult.size() != rects.size())
+        return false;
+    m_result.resize(bestResult.size());
+    for (decltype(bestResult.size()) i = 0; i < bestResult.size(); ++i) {
+        const auto &result = bestResult[i];
+        const auto &rect = rects[i];
+        m_result[i] = {result.left / textureSize, result.top / textureSize, rect.width / textureSize, rect.height / textureSize, result.rotated};
+    }
+    return true;
+}
+
+void ChartPacker::pack()
+{
+    float initialGuessSize = std::sqrt(calculateTotalArea() * m_initialAreaGuessFactor);
+    float textureSize = initialGuessSize;
+    while (true) {
+        if (tryPack(textureSize))
+            break;
+        textureSize *= 1.0 + m_textureSizeGrowFactor;
+    }
+}
+
+}

simpleuv/chartpacker.h

@@ -0,0 +1,29 @@
+#ifndef SIMPLEUV_CHART_PACKER_H
+#define SIMPLEUV_CHART_PACKER_H
+#include <vector>
+
+namespace simpleuv
+{
+
+class ChartPacker
+{
+public:
+    void setCharts(const std::vector<std::pair<float, float>> &chartSizes);
+    const std::vector<std::tuple<float, float, float, float, bool>> &getResult();
+    void pack();
+    bool tryPack(float textureSize);
+
+private:
+    double calculateTotalArea();
+
+    std::vector<std::pair<float, float>> m_chartSizes;
+    std::vector<std::tuple<float, float, float, float, bool>> m_result;
+    float m_initialAreaGuessFactor = 1.0;
+    float m_textureSizeGrowFactor = 0.1;
+    float m_floatToIntFactor = 100;
+};
+
+}
+
+#endif
+

simpleuv/meshdatatype.h

@@ -12,7 +12,7 @@ struct Vertex
 
 struct Face
 {
-    int indicies[3];
+    size_t indicies[3];
 };
 
 struct TextureCoord