scummvm/graphics/tinygl/zmath.cpp

#include "common/scummsys.h"

#include "graphics/tinygl/zmath.h"

namespace TinyGL {

// Inversion of a general nxn matrix.
// Note : m is destroyed
int Matrix_Inv(float *r, float *m, int n) {
	int k;
	float max, tmp, t;

	// identitée dans r
	for (int i = 0; i < n * n; i++)
		r[i] = 0;
	for (int i = 0; i < n; i++)
		r[i * n + i] = 1;

	for (int j = 0; j < n; j++) {
		max = m[j * n + j];
		k = j;
		for (int i = j + 1; i < n; i++) {
			if (fabs(m[i * n + j]) > fabs(max)) {
				k = i;
				max = m[i * n + j];
			}
		}
		// non intersible matrix
		if (max == 0)
			return 1;

		if (k != j) {
			for (int i = 0; i < n; i++) {
				tmp = m[j * n + i];
				m[j * n + i] = m[k * n + i];
				m[k * n + i] = tmp;

				tmp = r[j * n + i];
				r[j * n + i] = r[k * n + i];
				r[k * n + i] = tmp;
			}
		}

		max = 1 / max;
		for (int i = 0; i < n; i++) {
			m[j * n + i] *= max;
			r[j * n + i] *= max;
		}


		for (int l = 0; l < n; l++) {
			if (l != j) {
				t = m[l * n + j];
				for (int i = 0; i < n; i++) {
					m[l * n + i] -= m[j * n + i] * t;
					r[l * n + i] -= r[j * n + i] * t;
				}
			}
		}
	}

	return 0;
}

Vector3::Vector3() {
	// Empty constructor, no overhead
}

Vector3::Vector3(const Vector3 &other) {
	memcpy(_v, other._v, sizeof(_v));
}

Vector3::Vector3(float x, float y, float z) {
	_v[0] = x;
	_v[1] = y;
	_v[2] = z;
}

void Vector3::normalize() {
	float n;
	n = sqrt(_v[0] * _v[0] + _v[1] * _v[1] + _v[2] * _v[2]);
	if (n != 0) {
		_v[0] /= n;
		_v[1] /= n;
		_v[2] /= n;
	}
}

Vector4::Vector4() {
	// Empty constructor, no overhead
}

Vector4::Vector4(float x, float y, float z, float w) {
	_v[0] = x;
	_v[1] = y;
	_v[2] = z;
	_v[3] = w;
}

Vector4::Vector4(const Vector3 &vec, float w) {
	_v[0] = vec.getX();
	_v[1] = vec.getY();
	_v[2] = vec.getZ();
	_v[3] = w;
}

Matrix4::Matrix4() {
	// Empty constructor, no overhead
}

Matrix4::Matrix4(const Matrix4 &other) {
	memcpy(_m, other._m, sizeof(_m));
}

TinyGL::Matrix4 Matrix4::identity() {
	Matrix4 a;
	a.fill(0);
	a.set(0, 0, 1.0f);
	a.set(1, 1, 1.0f);
	a.set(2, 2, 1.0f);
	a.set(3, 3, 1.0f);
	return a;
}

TinyGL::Matrix4 Matrix4::transpose() const {
	Matrix4 a;

	a.set(0, 0, this->get(0, 0));
	a.set(0, 1, this->get(1, 0));
	a.set(0, 2, this->get(2, 0));
	a.set(0, 3, this->get(3, 0));

	a.set(1, 0, this->get(0, 1));
	a.set(1, 1, this->get(1, 1));
	a.set(1, 2, this->get(2, 1));
	a.set(1, 3, this->get(3, 1));

	a.set(2, 0, this->get(0, 2));
	a.set(2, 1, this->get(1, 2));
	a.set(2, 2, this->get(2, 2));
	a.set(2, 3, this->get(3, 2));

	a.set(3, 0, this->get(0, 3));
	a.set(3, 1, this->get(1, 3));
	a.set(3, 2, this->get(2, 3));
	a.set(3, 3, this->get(3, 3));

	return a;
}

Matrix4 Matrix4::inverseOrtho() const {
	Matrix4 a;

	int i, j;
	float s;
	for (i = 0; i < 3; i++) {
		for (j = 0; j < 3; j++)
			a.set(i, j, this->get(j, i));
		a.set(3, 0, 0.0f);
		a.set(3, 1, 0.0f);
		a.set(3, 2, 0.0f);
		a.set(3, 3, 1.0f);
		for (i = 0; i < 3; i++) {
			s = 0;
			for (j = 0; j < 3; j++)
				s -= this->get(j, i) * this->get(j, 3);
			a.set(i,3,s);
		}
	}

	return a;
}

Matrix4 Matrix4::inverse() const {
	Matrix4 result;
	Matrix4 source = *this;
	Matrix_Inv((float *)result._m, (float *)source._m, 4);
	return result;
}

Matrix4 Matrix4::rotation(float t, int u) {
	Matrix4 a = identity();
	float s, c;
	int v, w;

	if ((v = u + 1) > 2)
		v = 0;
	if ((w = v + 1) > 2)
		w = 0;
	s = sin(t);
	c = cos(t);
	a.set(v, v, c);
	a.set(v, w, -s);
	a.set(w, v, s);
	a.set(w, w, c);

	return a;
}

Vector3 Matrix4::transform(const Vector3 &vector) const {
	return Vector3(
	           vector.getX() * get(0, 0) + vector.getY() * get(0, 1) + vector.getZ() * get(0, 2) + get(0, 3),
	           vector.getX() * get(1, 0) + vector.getY() * get(1, 1) + vector.getZ() * get(1, 2) + get(1, 3),
	           vector.getX() * get(2, 0) + vector.getY() * get(2, 1) + vector.getZ() * get(2, 2) + get(2, 3));
}

Vector3 Matrix4::transform3x3(const Vector3 &vector) const {
	return Vector3(
	           vector.getX() * get(0, 0) + vector.getY() * get(0, 1) + vector.getZ() * get(0, 2),
	           vector.getX() * get(1, 0) + vector.getY() * get(1, 1) + vector.getZ() * get(1, 2),
	           vector.getX() * get(2, 0) + vector.getY() * get(2, 1) + vector.getZ() * get(2, 2));
}

TinyGL::Vector4 Matrix4::transform3x4(const Vector4 &vector) const {
	return Vector4(
	           vector.getX() * get(0, 0) + vector.getY() * get(0, 1) + vector.getZ() * get(0, 2) + get(0, 3),
	           vector.getX() * get(1, 0) + vector.getY() * get(1, 1) + vector.getZ() * get(1, 2) + get(1, 3),
	           vector.getX() * get(2, 0) + vector.getY() * get(2, 1) + vector.getZ() * get(2, 2) + get(2, 3),
	           vector.getX() * get(3, 0) + vector.getY() * get(3, 1) + vector.getZ() * get(3, 2) + get(3, 3));
}

Vector4 Matrix4::transform(const Vector4 &vector) const {
	return Vector4(
	           vector.getX() * get(0, 0) + vector.getY() * get(0, 1) + vector.getZ() * get(0, 2) + vector.getW() * get(0, 3),
	           vector.getX() * get(1, 0) + vector.getY() * get(1, 1) + vector.getZ() * get(1, 2) + vector.getW() * get(1, 3),
	           vector.getX() * get(2, 0) + vector.getY() * get(2, 1) + vector.getZ() * get(2, 2) + vector.getW() * get(2, 3),
	           vector.getX() * get(3, 0) + vector.getY() * get(3, 1) + vector.getZ() * get(3, 2) + vector.getW() * get(3, 3));
}

bool Matrix4::IsIdentity() const {
	//NOTE: This might need to be implemented in a fault-tolerant way.
	for (int i = 0; i < 4; i++) {
		for (int j = 0; j < 4; j++) {
			if (i == j) {
				if (_m[i][j] != 1.0)
					return false;
			} else if (_m[i][j] != 0.0)
				return false;
		}
	}
	return true;
}

} // end of namespace TinyGL