public static void MatLookAt(ref Mat4 result, Vec3 eye, Vec3 at, Vec3 up)
{
Vec3 view = Vec3Normalize(
Vec3Sub(eye, at)
);
Vec3 uxv = Vec3Cross(up, view);
Vec3 right = Vec3Normalize(uxv);
up = Vec3Cross(view, right);
Mat4.ZeroSet(ref result);
result.M11 = right.X;
result.M12 = up.X;
result.M13 = view.X;
result.M21 = right.Y;
result.M22 = up.Y;
result.M23 = view.Y;
result.M31 = right.Z;
result.M32 = up.Z;
result.M33 = view.Z;
result.M41 = -Vec3Dot(right, eye);
result.M42 = -Vec3Dot(up, eye);
result.M43 = -Vec3Dot(view, eye);
result.M44 = 1.0f;
}
public static void MatOrtho(ref Mat4 result, float left, float right, float bottom, float top, float near, float far, float offset = 0f)
{
Mat4.ZeroSet(ref result);
result.M11 = 2.0f / (right - left);
result.M22 = 2.0f / (top - bottom);
result.M33 = 1.0f / (near - far);
result.M41 = (left + right) / (left - right) + offset;
result.M42 = (top + bottom) / (bottom - top);
result.M43 = near / (near - far);
result.M44 = 1.0f;
}
// ==================================================================
private static void MatProjXYWH(ref Mat4 result, float x, float y, float w, float h, float near, float far)
{
float diff = far - near;
float aa = far / diff;
float bb = near * aa;
Mat4.ZeroSet(ref result);
result.M11 = w;
result.M22 = h;
result.M31 = x;
result.M32 = y;
result.M33 = -aa;
result.M34 = -1.0f;
result.M43 = -bb;
}
public static void MatRotateXY(ref Mat4 result, float rx, float ry)
{
float sx = Sin(rx);
float cx = Cos(rx);
float sy = Sin(ry);
float cy = Cos(ry);
Mat4.ZeroSet(ref result);
result.M11 = cy;
result.M13 = sy;
result.M21 = sx * sy;
result.M22 = cx;
result.M23 = -sx * cy;
result.M31 = -cx * sy;
result.M32 = sx;
result.M33 = cx * cy;
result.M44 = 1.0f;
}