TriangleBox.js

function PlaneBoxCollision(normal, vertex, maxBox)
{
    var q;
    var vmin = [], vmax = [], v;
    for(q = 0; q <= 2; q++)
    {
        v = vertex[q];
        if(normal[q] > 0)
        {
            vmin[q] = - maxBox[q] - v;
            vmax[q] = maxBox[q] - v;
        }
        else
        {
            vmin[q] = maxBox[q] - v;
            vmax[q] = - maxBox[q] - v;
        }
    }
    if((normal[0] * vmin[0]) + (normal[1] * vmin[1]) + (normal[2] * vmin[2]) > 0) return 0;
    if((normal[0] * vmax[0]) + (normal[1] * vmax[1]) + (normal[2] * vmax[2]) >= 0) return 1;
    return 0;
}

function TriangleBoxCollision(boxCenter, boxHalfSize, triangleVertices)
{
    var v0 = [], v1 = [], v2 = [];
    var min, max, p0, p1, p2, rad, fex, fey, fez;
    var normal = [], e0 = [], e1 = [], e2 = [];
    v0[0] = triangleVertices[0][0] - boxCenter[0];
    v0[1] = triangleVertices[0][1] - boxCenter[1];
    v0[2] = triangleVertices[0][2] - boxCenter[2];
    v1[0] = triangleVertices[1][0] - boxCenter[0];
    v1[1] = triangleVertices[1][1] - boxCenter[1];
    v1[2] = triangleVertices[1][2] - boxCenter[2];
    v2[0] = triangleVertices[2][0] - boxCenter[0];
    v2[1] = triangleVertices[2][1] - boxCenter[1];
    v2[2] = triangleVertices[2][2] - boxCenter[2];
    e0[0] = v1[0] - v0[0];
    e0[1] = v1[1] - v0[1];
    e0[2] = v1[2] - v0[2];
    e1[0] = v2[0] - v1[0];
    e1[1] = v2[1] - v1[1];
    e1[2] = v2[2] - v1[2];
    e2[0] = v0[0] - v2[0];
    e2[1] = v0[1] - v2[1];
    e2[2] = v0[2] - v2[2];
    fex = Math.abs(e0[0]);
    fey = Math.abs(e0[1]);
    fez = Math.abs(e0[2]);
    p0 = e0[2] * v0[1] - e0[1] * v0[2];
    p2 = e0[2] * v2[1] - e0[1] * v2[2];
    if(p0 < p2)
    {
        min = p0;
        max = p2;
    }
    else
    {
        min = p2;
        max = p0;
    }
    rad = fez * boxHalfSize[1] + fey * boxHalfSize[2];
    if((min > rad) || (max < -rad)) return 0;
    p0 = -e0[2] * v0[0] + e0[0] * v0[2];
    p2 = -e0[2] * v2[0] + e0[0] * v2[2];
    if(p0 < p2)
    {
        min = p0;
        max = p2;
    }
    else
    {
        min = p2;
        max = p0;
    }
    rad = fez * boxHalfSize[0] + fex * boxHalfSize[2];
    if((min > rad) || (max < -rad)) return 0;
    p1 = e0[1] * v1[0] - e0[0] * v1[1];
    p2 = e0[1] * v2[0] - e0[0] * v2[1];
    if(p2 < p1)
    {
        min = p2;
        max = p1;
    }
    else
    {
        min = p1;
        max = p2;
    }
    rad = fey * boxHalfSize[0] + fex * boxHalfSize[1];
    if((min > rad) || (max < -rad)) return 0;
    fex = Math.abs(e1[0]);
    fey = Math.abs(e1[1]);
    fez = Math.abs(e1[2]);
    p0 = e1[2] * v0[1] - e1[1] * v0[2];
    p2 = e1[2] * v2[1] - e1[1] * v2[2];
    if(p0 < p2)
    {
        min = p0;
        max = p2;
    }
    else
    {
        min = p2;
        max = p0;
    }
    rad = fez * boxHalfSize[1] + fey * boxHalfSize[2];
    if((min > rad) || (max < -rad)) return 0;
    p0 = -e1[2] * v0[0] + e1[0] * v0[2];
    p2 = -e1[2] * v2[0] + e1[0] * v2[2];
    if(p0 < p2)
    {
        min = p0;
        max = p2;
    }
    else
    {
        min = p2;
        max = p0;
    }
    rad = fez * boxHalfSize[0] + fex * boxHalfSize[2];
    if((min > rad) || (max < -rad)) return 0;
    p0 = e1[1] * v0[0] - e1[0] * v0[1];
    p1 = e1[1] * v1[0] - e1[0] * v1[1];
    if(p0 < p1)
    {
        min = p0;
        max = p1;
    }
    else
    {
        min = p1;
        max = p0;
    }
    rad = fey * boxHalfSize[0] + fex * boxHalfSize[1];
    if((min > rad) || (max < -rad)) return 0;
    fex = Math.abs(e2[0]);
    fey = Math.abs(e2[1]);
    fez = Math.abs(e2[2]);
    p0 = e2[2] * v0[1] - e2[1] * v0[2];
    p1 = e2[2] * v1[1] - e2[1] * v1[2];
    if(p0 < p1)
    {
        min = p0;
        max = p1;
    }
    else
    {
        min = p1;
        max = p0;
    }
    rad = fez * boxHalfSize[1] + fey * boxHalfSize[2];
    if((min > rad) || (max < -rad)) return 0;
    p0 = -e2[2] * v0[0] + e2[0] * v0[2];
    p1 = -e2[2] * v1[0] + e2[0] * v1[2];
    if(p0 < p1)
    {
        min = p0;
        max = p1;
    }
    else
    {
        min = p1;
        max = p0;
    }
    rad = fez * boxHalfSize[0] + fex * boxHalfSize[2];
    if((min > rad) || (max < -rad)) return 0;
    p1 = e2[1] * v1[0] - e2[0] * v1[1];
    p2 = e2[1] * v2[0] - e2[0] * v2[1];
    if(p2 < p1)
    {
        min = p2;
        max = p1;
    }
    else
    {
        min = p1;
        max = p2;
    }
    rad = fey * boxHalfSize[0] + fex * boxHalfSize[1];
    if((min > rad) || (max < -rad)) return 0;
    min = Math.min(v0[0], v1[0], v2[0]);
    max = Math.max(v0[0], v1[0], v2[0]);
    if((min > boxHalfSize[0]) || (max < -boxHalfSize[0])) return 0;
    min = Math.min(v0[1], v1[1], v2[1]);
    max = Math.max(v0[1], v1[1], v2[1]);
    if((min > boxHalfSize[1]) || (max < -boxHalfSize[1])) return 0;
    min = Math.min(v0[2], v1[2], v2[2]);
    max = Math.max(v0[2], v1[2], v2[2]);
    if((min > boxHalfSize[2]) || (max < -boxHalfSize[2])) return 0;
    normal[0] = e0[1] * e1[2] - e0[2] * e1[1];
    normal[1] = e0[2] * e1[0] - e0[0] * e1[2];
    normal[2] = e0[0] * e1[1] - e0[1] * e1[0];
    if(!PlaneBoxCollision(normal, v0, boxHalfSize)) return 0;
    return 1;
}