Mesh of Box

Warning! Some information on this page is older than 6 years now. I keep it for reference, but it probably doesn't reflect my current knowledge and beliefs.

Mon
21
Jan 2013

Too many times I had to come up with triangle mesh of a box to hardcode it in my program, written just from memory or with help of a sheet of paper. It's easy to make a mistake and have a box with one face missing or something like that. So in case me or somebody in the future will need it, here it is. Parameters:

Box spanning from (-1, -1, -1) to (+1, +1, +1). Contains 3D positions and normals. Topology is triangle strip, using strip-cut index. Backface culling can be used, front faces are clockwise (using Direct3D coordinate system).

// H file

struct SVertex {
    vec3 Position;
    vec3 Normal;
};

const size_t BOX_VERTEX_COUNT = 6 * 4;
const size_t BOX_INDEX_COUNT  = 6 * 5;
extern const SVertex BOX_VERTICES[];
extern const uint16_t BOX_INDICES[];

// CPP file

const SVertex BOX_VERTICES[] = {
    // -X
    { vec3(-1.f, -1.f,  1.f), vec3(-1.f,  0.f,  0.f) },
    { vec3(-1.f,  1.f,  1.f), vec3(-1.f,  0.f,  0.f) },
    { vec3(-1.f, -1.f, -1.f), vec3(-1.f,  0.f,  0.f) },
    { vec3(-1.f,  1.f, -1.f), vec3(-1.f,  0.f,  0.f) },
    // -Z
    { vec3(-1.f, -1.f, -1.f), vec3( 0.f,  0.f, -1.f) },
    { vec3(-1.f,  1.f, -1.f), vec3( 0.f,  0.f, -1.f) },
    { vec3( 1.f, -1.f, -1.f), vec3( 0.f,  0.f, -1.f) },
    { vec3( 1.f,  1.f, -1.f), vec3( 0.f,  0.f, -1.f) },
    // +X
    { vec3( 1.f, -1.f, -1.f), vec3( 1.f,  0.f,  0.f) },
    { vec3( 1.f,  1.f, -1.f), vec3( 1.f,  0.f,  0.f) },
    { vec3( 1.f, -1.f,  1.f), vec3( 1.f,  0.f,  0.f) },
    { vec3( 1.f,  1.f,  1.f), vec3( 1.f,  0.f,  0.f) },
    // +Z
    { vec3( 1.f, -1.f,  1.f), vec3( 0.f,  0.f,  1.f) },
    { vec3( 1.f,  1.f,  1.f), vec3( 0.f,  0.f,  1.f) },
    { vec3(-1.f, -1.f,  1.f), vec3( 0.f,  0.f,  1.f) },
    { vec3(-1.f,  1.f,  1.f), vec3( 0.f,  0.f,  1.f) },
    // -Y
    { vec3(-1.f, -1.f,  1.f), vec3( 0.f, -1.f,  0.f) },
    { vec3(-1.f, -1.f, -1.f), vec3( 0.f, -1.f,  0.f) },
    { vec3( 1.f, -1.f,  1.f), vec3( 0.f, -1.f,  0.f) },
    { vec3( 1.f, -1.f, -1.f), vec3( 0.f, -1.f,  0.f) },
    // +Y
    { vec3(-1.f,  1.f, -1.f), vec3( 0.f,  1.f,  0.f) },
    { vec3(-1.f,  1.f,  1.f), vec3( 0.f,  1.f,  0.f) },
    { vec3( 1.f,  1.f, -1.f), vec3( 0.f,  1.f,  0.f) },
    { vec3( 1.f,  1.f,  1.f), vec3( 0.f,  1.f,  0.f) },
};

const uint16_t BOX_INDICES[] = {
     0,  1,  2,  3, 0xFFFF, // -X
     4,  5,  6,  7, 0xFFFF, // -Z
     8,  9, 10, 11, 0xFFFF, // +X
    12, 13, 14, 15, 0xFFFF, // +Z
    16, 17, 18, 19, 0xFFFF, // -Y
    20, 21, 22, 23, 0xFFFF, // +Y
};

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