bc_lib.bc

/* Subtract the second vector from the first vector */
define vec_diff(v1[], v2[], *vdiff[]) {
    auto i
    for (i = 0; i < 3; ++i)
        vdiff[i] = v1[i] - v2[i]
}

/* Dot product of two vectors */
define dot_prod(v1[], v2[]) {
    auto i, prod
    for (i = 0; i < 3; ++i)
        prod += v1[i] * v2[i]
    return prod
}

/* Cross product of two vectors */
define cross_prod(v1[], v2[], *vcr[]) {
    vcr[0] = v1[1] * v2[2] - v1[2] * v2[1]
    vcr[1] = v1[2] * v2[0] - v1[0] * v2[2]
    vcr[2] = v1[0] * v2[1] - v1[1] * v2[0]
}

/* Normalize a vector */
define normalize(*v[]) {
    auto len, i
    len = sqrt(v[0]^2 + v[1]^2 + v[2]^2)
    for (i = 0; i < 3; ++i)
        v[i] /= len
}

/* Invert a vector */
define invert(*v[]) {
    auto i
    for (i = 0; i < 3; ++i)
        v[i] *= -1
}

/* Absolute value */
define abs(val) {
    if (val > 0) {
        return val
    } else {
        return -val
    }
}

/* Floor towards next smaller number (and not zero) 
   pay attention to scale, should be 0 */
define floor(val) {
    if (val > 0) {
        return val - (val % 1)
    } else {
        return val - (val % 1) - 1
    }
}

/* Return smaller of two values */
define min(a, b) {
    if (a < b) {
        return a
    } else {
        return b
    }
}

/* Return larger of two values */
define max(a, b) {
    if (a > b) {
        return a
    } else {
        return b
    }
}