/// <summary>
/// 把连续9个float值按照列优先的顺序转换为mat3
/// </summary>
/// <param name="values"></param>
/// <param name="startIndex"></param>
/// <returns></returns>
public static mat3 ToMat3(this float[] values, int startIndex = 0)
{
mat3 result = new mat3(
values.ToVec3(startIndex + 0), values.ToVec3(startIndex + 3), values.ToVec3(startIndex + 6));
return(result);
}
/// <summary>
/// Build a look at view matrix.
/// transform object's coordinate from world's space to camera's space.
/// </summary>
/// <param name="eye">The eye.</param>
/// <param name="center">The center.</param>
/// <param name="up">Up.</param>
/// <returns></returns>
public static mat3 lookAt(vec2 eye, vec2 center, bool up)
{
// camera's back in world space coordinate system
vec2 back = (eye - center).normalize();
// camera's right in world space coordinate system
vec2 right = up.cross(back).normalize();
if (!up)
{
right = -right;
}
mat3 viewMatrix = new mat3(1);
viewMatrix.col0.x = right.x;
viewMatrix.col1.x = right.y;
viewMatrix.col0.y = back.x;
viewMatrix.col1.y = back.y;
// Translation in world space coordinate system
viewMatrix.col3.x = -eye.dot(right);
viewMatrix.col3.y = -eye.dot(back);
return(viewMatrix);
}
/// <summary>
/// Applies a translation transformation to matrix <paramref name="m"/> by vector <paramref name="v"/>.
/// </summary>
/// <param name="m">The matrix to transform.</param>
/// <param name="v">The vector to translate by.</param>
/// <returns><paramref name="m"/> translated by <paramref name="v"/>.</returns>
public static mat3 translate(mat3 m, vec2 v)
{
mat3 result = m;
result.col2 = m.col0 * v.x + m.col1 * v.y + m.col2;
return(result);
}
/// <summary>
/// Applies a scale transformation to matrix <paramref name="m"/> by vector <paramref name="v"/>.
/// </summary>
/// <param name="m">The matrix to transform.</param>
/// <param name="v">The vector to scale by.</param>
/// <returns><paramref name="m"/> scaled by <paramref name="v"/>.</returns>
public static mat3 scale(mat3 m, vec2 v)
{
mat3 result = m;
result.col0 = m.col0 * v.x;
result.col1 = m.col1 * v.y;
result.col2 = m.col2;
return(result);
}
/// Builds a rotation 3 * 3 matrix created from an angle.
/// </summary>
/// <param name="m">The m.</param>
/// <param name="angleDegree">ANgle in Degree.</param>
/// <returns></returns>
public static mat3 rotate(mat3 m, float angleDegree)
{
float c = (float)Math.Cos(angleDegree * Math.PI / 180.0);
float s = (float)Math.Sin(angleDegree * Math.PI / 180.0);
mat3 rotate = mat3.identity();
rotate.col0 = new vec2(c, s);
rotate.col1 = new vec2(-s, c);
mat3 result = rotate * m;
return(result);
}
internal override bool SetValue(ValueType value)
{
if (value.GetType() != typeof(mat3))
{
throw new ArgumentException(string.Format("[{0}] not match [{1}]'s value.",
value.GetType().Name, this.GetType().Name));
}
var v = (mat3)value;
if (v != this.value)
{
this.value = v;
this.Updated = true;
return(true);
}
else
{
return(false);
}
}
/// <summary>
/// Multiplies the <paramref name="lhs"/> matrix by the <paramref name="rhs"/> matrix.
/// </summary>
/// <param name="lhs">The LHS matrix.</param>
/// <param name="rhs">The RHS matrix.</param>
/// <returns>The product of <paramref name="lhs"/> and <paramref name="rhs"/>.</returns>
public static mat3 operator *(mat3 lhs, mat3 rhs)
{
mat3 result = new mat3(
new vec3(
lhs[0][0] * rhs[0][0] + lhs[1][0] * rhs[0][1] + lhs[2][0] * rhs[0][2],
lhs[0][1] * rhs[0][0] + lhs[1][1] * rhs[0][1] + lhs[2][1] * rhs[0][2],
lhs[0][2] * rhs[0][0] + lhs[1][2] * rhs[0][1] + lhs[2][2] * rhs[0][2]
),
new vec3(
lhs[0][0] * rhs[1][0] + lhs[1][0] * rhs[1][1] + lhs[2][0] * rhs[1][2],
lhs[0][1] * rhs[1][0] + lhs[1][1] * rhs[1][1] + lhs[2][1] * rhs[1][2],
lhs[0][2] * rhs[1][0] + lhs[1][2] * rhs[1][1] + lhs[2][2] * rhs[1][2]
),
new vec3(
lhs[0][0] * rhs[2][0] + lhs[1][0] * rhs[2][1] + lhs[2][0] * rhs[2][2],
lhs[0][1] * rhs[2][0] + lhs[1][1] * rhs[2][1] + lhs[2][1] * rhs[2][2],
lhs[0][2] * rhs[2][0] + lhs[1][2] * rhs[2][1] + lhs[2][2] * rhs[2][2]
)
);
return(result);
}
