initial commit

TileLayout.cpp

@@ -0,0 +1,121 @@
+#include "TileLayout.hpp"
+
+#include <algorithm>
+#include <cmath>
+
+namespace
+{
+std::vector<Vertex> makeQuad(
+    float x0,
+    float y0,
+    float x1,
+    float y1)
+{
+    return {
+        {{x0, y0}, {0.0f, 0.0f}},
+        {{x1, y0}, {1.0f, 0.0f}},
+        {{x1, y1}, {1.0f, 1.0f}},
+
+        {{x0, y0}, {0.0f, 0.0f}},
+        {{x1, y1}, {1.0f, 1.0f}},
+        {{x0, y1}, {0.0f, 1.0f}},
+    };
+}
+}
+
+std::vector<Vertex> makeGridLayout(
+    uint32_t cols,
+    uint32_t rows,
+    float gapX,
+    float gapY)
+{
+    std::vector<Vertex> vertices;
+    vertices.reserve(
+        static_cast<size_t>(cols) * rows * 6);
+
+    const float tileW =
+        (2.0f - gapX * static_cast<float>(cols - 1)) /
+        static_cast<float>(cols);
+    const float tileH =
+        (2.0f - gapY * static_cast<float>(rows - 1)) /
+        static_cast<float>(rows);
+
+    for (uint32_t row = 0; row < rows; ++row)
+    {
+        for (uint32_t col = 0; col < cols; ++col)
+        {
+            const float x0 =
+                -1.0f +
+                static_cast<float>(col) * (tileW + gapX);
+            const float y0 =
+                -1.0f +
+                static_cast<float>(row) * (tileH + gapY);
+            const float x1 = x0 + tileW;
+            const float y1 = y0 + tileH;
+
+            auto quad = makeQuad(x0, y0, x1, y1);
+            vertices.insert(
+                vertices.end(),
+                quad.begin(),
+                quad.end());
+        }
+    }
+
+    return vertices;
+}
+
+void updateGridLayout(
+    Vertex* vertices,
+    uint32_t cols,
+    uint32_t rows,
+    float gapX,
+    float gapY)
+{
+    std::vector<Vertex> updated =
+        makeGridLayout(cols, rows, gapX, gapY);
+
+    std::copy(
+        updated.begin(),
+        updated.end(),
+        vertices
+    );
+}
+
+void updateUvForAspectRatio(
+    Vertex* vertices,
+    uint32_t quadIndex,
+    float srcAspect,
+    float tileAspect)
+{
+    Vertex* quad = vertices + quadIndex * 6;
+
+    float uMin = 0.0f;
+    float uMax = 1.0f;
+    float vMin = 0.0f;
+    float vMax = 1.0f;
+
+    if (srcAspect > tileAspect)
+    {
+        float scale = tileAspect / srcAspect;
+        float bar = (1.0f - scale) * 0.5f;
+        vMin = bar;
+        vMax = 1.0f - bar;
+    }
+    else if (srcAspect < tileAspect)
+    {
+        float scale = srcAspect / tileAspect;
+        float bar = (1.0f - scale) * 0.5f;
+        uMin = bar;
+        uMax = 1.0f - bar;
+    }
+
+    // Triangle 1: vertices 0-2
+    quad[0].uv[0] = uMin; quad[0].uv[1] = vMin;
+    quad[1].uv[0] = uMax; quad[1].uv[1] = vMin;
+    quad[2].uv[0] = uMax; quad[2].uv[1] = vMax;
+
+    // Triangle 2: vertices 3-5
+    quad[3].uv[0] = uMin; quad[3].uv[1] = vMin;
+    quad[4].uv[0] = uMax; quad[4].uv[1] = vMax;
+    quad[5].uv[0] = uMin; quad[5].uv[1] = vMax;
+}