Matrix4x4 Matrix4x4::FromScale(Vector3 scale)
{
Matrix4x4 matrix = Matrix4x4::identity;
//Scalar matrix has values on the diagonal
// | x 0 0 0 |
// | 0 y 0 0 |
// | 0 0 z 0 |
// | 0 0 0 1 |
matrix.RowCol(0, 0) = scale.x;
matrix.RowCol(1, 1) = scale.y;
matrix.RowCol(2, 2) = scale.z;
return matrix;
}
Matrix4x4 Matrix4x4::FromPosition(Vector3 position)
{
Matrix4x4 matrix = Matrix4x4::identity;
//Translation matrix has values in the last column
// | 1 0 0 x |
// | 0 1 0 y |
// | 0 0 1 z |
// | 0 0 0 1 |
matrix.RowCol(0, 3) = position.x;
matrix.RowCol(1, 3) = position.y;
matrix.RowCol(2, 3) = position.z;
return matrix;
}
Matrix4x4 Matrix4x4::Orthographic(float left, float right, float bottom, float top, float near, float far)
{
//http://www.songho.ca/opengl/gl_projectionmatrix.html
Matrix4x4 matrix = Matrix4x4::identity;
//Scale components
matrix.RowCol(0, 0) = 2 / (right - left);
matrix.RowCol(1, 1) = 2 / (top - bottom);
matrix.RowCol(2, 2) = -2 / (far - near);
//Translate components
matrix.RowCol(0, 3) = -(right + left) / (right - left);
matrix.RowCol(1, 3) = -(top + bottom) / (top - bottom);
matrix.RowCol(2, 3) = -(far + near) / (far - near);
return matrix;
}
Matrix4x4 Matrix4x4::Perspective(float left, float right, float bottom, float top, float near, float far)
{
//http://www.songho.ca/opengl/gl_projectionmatrix.html
Matrix4x4 matrix = Matrix4x4::zero;
matrix.RowCol(0, 0) = 2 * near / (right - left);
matrix.RowCol(0, 2) = (right + left) / (right - left);
matrix.RowCol(1, 1) = 2 * near / (top - bottom);
matrix.RowCol(1, 2) = (top + bottom) / (top - bottom);
matrix.RowCol(2, 2) = -(far + near) / (far - near);
matrix.RowCol(2, 3) = -2 * far * near / (far - near);
matrix.RowCol(3, 2) = -1;
return matrix;
}
Matrix4x4 Matrix4x4::FromRotation(Quaternion rotation)
{
//rotation.Normalize();
Matrix4x4 matrix = Matrix4x4::identity;
float a = rotation.w;
float b = rotation.x;
float c = rotation.y;
float d = rotation.z;
float aSqr = a * a;
float bSqr = b * b;
float cSqr = c * c;
float dSqr = d * d;
matrix.RowCol(0, 0) = aSqr + bSqr - cSqr - dSqr;
matrix.RowCol(0, 1) = (2 * b * c) - (2 * a * d);
matrix.RowCol(0, 2) = (2 * b * d) + (2 * a * c);
matrix.RowCol(1, 0) = (2 * b * c) + (2 * a * d);
matrix.RowCol(1, 1) = aSqr - bSqr + cSqr - dSqr;
matrix.RowCol(1, 2) = (2 * c * d) - (2 * a * b);
matrix.RowCol(2, 0) = (2 * b * d) - (2 * a * c);
matrix.RowCol(2, 1) = (2 * c * d) + (2 * a * b);
matrix.RowCol(2, 2) = aSqr - bSqr - cSqr + dSqr;
return matrix;
}
