/// <summary>
/// Calculates a screen space scissor rectangle using the given Camera. If the Camera is null than the scissor will
/// be calculated only with the batchTransform
/// </summary>
/// <returns>The scissors.</returns>
/// <param name="camera">Camera.</param>
/// <param name="batchTransform">Batch transform.</param>
/// <param name="scissor">Area.</param>
public static Rectangle CalculateScissors(Camera camera, Matrix2D batchTransform, Rectangle scissor)
{
var batchTrans = batchTransform.ToSimd();
// convert the top-left point to screen space
var tmp = new System.Numerics.Vector2(scissor.X, scissor.Y);
tmp = System.Numerics.Vector2.Transform(tmp, batchTrans);
if (camera != null)
{
tmp = camera.WorldToScreenPoint(tmp);
}
var newScissor = new Rectangle();
newScissor.X = (int)tmp.X;
newScissor.Y = (int)tmp.Y;
// convert the bottom-right point to screen space
tmp.X = scissor.X + scissor.Width;
tmp.Y = scissor.Y + scissor.Height;
tmp = System.Numerics.Vector2.Transform(tmp, batchTrans);
if (camera != null)
{
tmp = camera.WorldToScreenPoint(tmp);
}
newScissor.Width = (int)tmp.X - newScissor.X;
newScissor.Height = (int)tmp.Y - newScissor.Y;
return(newScissor);
}