cubit/cube.h at main · mzschwartz5/cubit · GitHub

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#pragma once
#include <array>

/**
 * The 8 corners of a unit cube centered at the origin.
 * (Ordered in Morton-code order according to https://dl.acm.org/doi/pdf/10.1145/3677388.3696322)
 */
inline std::array<std::array<float, 3>, 8> cubeCorners = {{
    {{-0.5f, -0.5f, -0.5f}},
    {{ 0.5f, -0.5f, -0.5f}},
    {{-0.5f,  0.5f, -0.5f}},
    {{ 0.5f,  0.5f, -0.5f}},
    {{-0.5f, -0.5f,  0.5f}},
    {{ 0.5f, -0.5f,  0.5f}},
    {{-0.5f,  0.5f,  0.5f}},
    {{ 0.5f,  0.5f,  0.5f}}
}};

inline std::array<std::array<int, 2>, 12> cubeEdges = {{
    {{0, 1}}, {{1, 3}}, {{3, 2}}, {{2, 0}}, // bottom face
    {{4, 5}}, {{5, 7}}, {{7, 6}}, {{6, 4}}, // top face
    {{0, 4}}, {{1, 5}}, {{2, 6}}, {{3, 7}}  // vertical edges
}};

inline std::array<std::array<int, 3>, 12> cubeFaces = {
    // This matches the order expected in the voxel paint shaders.
    std::array<int,3>{0,4,6}, std::array<int,3>{0,6,2}, // -X
    std::array<int,3>{1,3,7}, std::array<int,3>{1,7,5}, // +X
    std::array<int,3>{0,1,5}, std::array<int,3>{0,5,4}, // -Y
    std::array<int,3>{6,7,3}, std::array<int,3>{6,3,2}, // +Y
    std::array<int,3>{2,3,1}, std::array<int,3>{2,1,0}, // -Z
    std::array<int,3>{4,5,7}, std::array<int,3>{4,7,6}  // +Z
};

inline constexpr std::array<float, 24> cubeCornersFlattened = {{
    -0.5f, -0.5f, -0.5f,
     0.5f, -0.5f, -0.5f,
    -0.5f,  0.5f, -0.5f,
     0.5f,  0.5f, -0.5f,
    -0.5f, -0.5f,  0.5f,
     0.5f, -0.5f,  0.5f,
    -0.5f,  0.5f,  0.5f,
     0.5f,  0.5f,  0.5f
}};

inline constexpr std::array<uint32_t, 24> cubeEdgesFlattened = {{
    0,1, 1,3, 3,2, 2,0,
    4,5, 5,7, 7,6, 6,4,
    0,4, 1,5, 2,6, 3,7
}};

inline constexpr std::array<uint32_t, 36> cubeFacesFlattened = {{
    // -X
    0,4,6, 0,6,2,
    // +X
    1,3,7, 1,7,5,
    // -Y
    0,1,5, 0,5,4,
    // +Y
    6,7,3, 6,3,2,
    // -Z
    2,3,1, 2,1,0,
    // +Z
    4,5,7, 4,7,6
}};

/**
 * This gets used as the vertex buffer for drawing cubes in particle mode:
 * all points are at the center of the cube, and the vertex shader expands them out to the corners.
 */
inline constexpr std::array<float, 12> cubeQuadVertsFlattened = {
    0.0f, 0.0f, 0.0f,
    0.0f, 0.0f, 0.0f,
    0.0f, 0.0f, 0.0f,
    0.0f, 0.0f, 0.0f
};

/**
 * When drawing a cube in particle mode, each corner is really a two-triangle quad.
 * We need six indices to draw a quad, and then do the expansion in the vertex shader.
 */
inline constexpr std::array<uint32_t, 6> cubeQuadIndicesFlattened = {{
    0, 1, 3, 0, 3, 2
}};