Triangle.cpp

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#include <tdme/engine/primitives/Triangle.h>
 
#include <tdme/tdme.h>
#include <tdme/math/Math.h>
#include <tdme/math/Vector3.h>
 
using tdme::engine::primitives::Triangle;
 
using tdme::math::Math;
using tdme::math::Vector3;
 
Triangle::Triangle()
{
    this->vertices.resize(3);
}
 
Triangle::Triangle(const Vector3& vertex0, const Vector3& vertex1, const Vector3& vertex2)
{
    this->vertices.resize(3);
    this->vertices[0].set(vertex0);
    this->vertices[1].set(vertex1);
    this->vertices[2].set(vertex2);
}
 
void Triangle::computeClosestPointOnBoundingVolume(const Vector3& point, Vector3& closestPoint) const {
    // see: http://www.gamedev.net/topic/552906-closest-point-on-triangle/
    Vector3 edge0;
    Vector3 edge1;
    Vector3 v0Point;
    edge0.set(vertices[1]).sub(vertices[0]);
    edge1.set(vertices[2]).sub(vertices[0]);
    v0Point.set(vertices[0]).sub(point);
    auto a = Vector3::computeDotProduct(edge0, edge0);
    auto b = Vector3::computeDotProduct(edge0, edge1);
    auto c = Vector3::computeDotProduct(edge1, edge1);
    auto d = Vector3::computeDotProduct(edge0, v0Point);
    auto e = Vector3::computeDotProduct(edge1, v0Point);
    auto det = a * c - b * b;
    auto s = b * e - c * d;
    auto t = b * d - a * e;
    if (s + t < det) {
        if (s < 0.0f) {
            if (t < 0.0f) {
                if (d < 0.0f) {
                    s = Math::clamp(-d / a, 0.0f, 1.0f);
                    t = 0.0f;
                } else {
                    s = 0.0f;
                    t = Math::clamp(-e / c, 0.0f, 1.0f);
                }
            } else {
                s = 0.0f;
                t = Math::clamp(-e / c, 0.0f, 1.0f);
            }
        } else if (t < 0.0f) {
            s = Math::clamp(-d / a, 0.0f, 1.0f);
            t = 0.0f;
        } else {
            auto invDet = 1.0f / det;
            s *= invDet;
            t *= invDet;
        }
    } else {
        if (s < 0.0f) {
            auto tmp0 = b + d;
            auto tmp1 = c + e;
            if (tmp1 > tmp0) {
                auto numer = tmp1 - tmp0;
                auto denom = a - 2 * b + c;
                s = Math::clamp(numer / denom, 0.0f, 1.0f);
                t = 1 - s;
            } else {
                t = Math::clamp(-e / c, 0.0f, 1.0f);
                s = 0.0f;
            }
        } else if (t < 0.0f) {
            if (a + d > b + e) {
                auto numer = c + e - b - d;
                auto denom = a - 2 * b + c;
                s = Math::clamp(numer / denom, 0.0f, 1.0f);
                t = 1 - s;
            } else {
                s = Math::clamp(-e / c, 0.0f, 1.0f);
                t = 0.0f;
            }
        } else {
            auto numer = c + e - b - d;
            auto denom = a - 2 * b + c;
            s = Math::clamp(numer / denom, 0.0f, 1.0f);
            t = 1.0f - s;
        }
    }
    closestPoint.set(vertices[0]).add(edge0.scale(s)).add(edge1.scale(t));
}