Esempi in C++ (Cpp) per vec3_t::AbsSquared

Esempio n. 1

File: vec3.cpp Progetto: jnz/Lynx

bool vec3_t::RayCylinderIntersect(const vec3_t& pStart, const vec3_t& pDir,
                                  const vec3_t& edgeStart, const vec3_t& edgeEnd,
                                  const float radius,
                                  float* f)
{
    // math. for 3d game programming 2nd ed. page 270
    // assert(edgeStart != edgeEnd); // sloppy level design
    const vec3_t pa = edgeEnd - edgeStart;
    const vec3_t s0 = pStart - edgeStart;
    const float pa_squared = pa.AbsSquared();
    const float pa_isquared = 1.0f/pa_squared;

    // a
    const float pva = pDir * pa;
    const float a = pDir.AbsSquared() - pva*pva*pa_isquared;

    // b
    const float b = s0*pDir - (s0*pa)*(pva)*pa_isquared;

    // c
    const float ps0a = s0*pa;
    const float c = s0.AbsSquared() - radius*radius - ps0a*ps0a*pa_isquared;

    const float dis = b*b - a*c;
    if(dis < 0)
        return false;

    *f = (-b - lynxmath::Sqrt(dis))/a;
    const float collision = (pStart + *f*pDir - edgeStart)*pa;
    return collision >= 0 && collision <= pa_squared;
}