private static TextureFilter RenderBrushToTextureFilter(SolidColorBrush brush)
{
// Account for Opacity
Color color = brush.Color;
color = ColorOperations.Blend(
color,
Color.FromArgb(0, color.R, color.G, color.B),
Math.Max(Math.Min(brush.Opacity, 1.0), 0.0));
// We don't want to rely on RenderTargetBitmap for SolidColorBrush
return(new SolidColorTextureFilter(color));
}
public override Color FilteredErrorLookup(Point uvLow, Point uvHigh, Color computedColor)
{
int lowerIndex = 0;
int upperIndex = 0;
Color computedError;
// look for appropriate levels
while (upperIndex < levels.Count && mipmapFactor > levels[upperIndex].PixelSize)
{
upperIndex++;
}
upperIndex = Math.Min(upperIndex, levels.Count - 1);
lowerIndex = Math.Max(upperIndex - 1, 0);
// Now perform error lookup on the mipmap levels
if (lowerIndex == upperIndex)
{
// no need to blend, clear case of too near (pure bilinear mag)
// or too far (1 pixel last level)
computedError = levels[lowerIndex].FilteredErrorLookup(uvLow, uvHigh, computedColor);
}
else
{
// Find the colors of the adjacent levels
Color lowerLevel = levels[lowerIndex].FilteredErrorLookup(uvLow, uvHigh, computedColor);
Color upperLevel = levels[upperIndex].FilteredErrorLookup(uvLow, uvHigh, computedColor);
// Find a suitable blend factor
double lowerPixelSize = levels[lowerIndex].PixelSize;
double upperPixelSize = levels[upperIndex].PixelSize;
// upper pixel is 2x larger than lower pixel
double blendFactor = (mipmapFactor / lowerPixelSize) - 1;
// return the mix
computedError = ColorOperations.Blend(upperLevel, lowerLevel, blendFactor);
}
// Compare against bilinear error
Color baseError = base.FilteredErrorLookup(uvLow, uvHigh, computedColor);
computedError = ColorOperations.Max(computedError, baseError);
return(computedError);
}
public override Color FilteredTextureLookup(Point uv)
{
int lowerIndex = 0;
int upperIndex = 0;
// look for appropriate levels
while (upperIndex < levels.Count && mipmapFactor > levels[upperIndex].PixelSize)
{
upperIndex++;
}
upperIndex = Math.Min(upperIndex, levels.Count - 1);
lowerIndex = Math.Max(upperIndex - 1, 0);
// Now perform texture lookup on the mipmap levels
if (lowerIndex == upperIndex)
{
// no need to blend, clear case of too near (pure bilinear mag)
// or too far (1 pixel last level)
return(levels[lowerIndex].FilteredTextureLookup(uv));
}
else
{
// Find the colors of the adjacent levels
Color lowerLevel = levels[lowerIndex].FilteredTextureLookup(uv);;
Color upperLevel = levels[upperIndex].FilteredTextureLookup(uv);;
// Find a suitable blend factor
double lowerPixelSize = levels[lowerIndex].PixelSize;
double upperPixelSize = levels[upperIndex].PixelSize;
// upper pixel is 2x larger than lower pixel
double blendFactor = (mipmapFactor / lowerPixelSize) - 1;
// return the mix
return(ColorOperations.Blend(upperLevel, lowerLevel, blendFactor));
}
}
/// <summary>
/// Get the pixel from the FrameBuffer at the specified Point.
/// This method uses Bilinear interpolation to determine the Color value.
/// If the Point is outside the bounds of the FrameBuffer, return null.
/// </summary>
private Color?GetPixel(Point point)
{
// point is somewhere in a pixel:
// pixel center is at ( 0.5, 0.5 ) and is already factored into this point.
// we need to find the weights of the surrounding pixel centers and interpolate to find the value
//
// x x' x"
// +-------+-------+ y
// | | |
// | 1.......2 | y'
// | : o | : | // o is at ( point.X, point.Y )
// +---:---+---:---+
// | : | : |
// | 3.......4 | y"
// | | |
// +-------+-------+
//
// x = floor( point.X - 0.5 )
// x' = x + 0.5
// x" = x + 1.5
// y = floor( point.Y - 0.5 )
// y' = y + 0.5
// y" = y + 1.5
// leftWeight = 1 - (point.X - x')
// rightWeight = (point.X - x')
// topWeight = 1 - (point.Y - y')
// bottomWeight = (point.Y - y')
//
// +-------+-------+
// | | |
// | 1.5.....2 | // 5 is the interpolated color at (point.X,y')
// | : o | : |
// +---:-|-+---:---+
// | : | | : |
// | 3.6.....4 | // 6 is the interpolated color at (point.X,y")
// | | |
// +-------+-------+
// p5 = p1*leftWeight + p2*rightWeight
// p6 = p3*leftWeight + p4*rightWeight
// o = p5*topWeight + p6*bottomWeight
int x = (int)Math.Floor(point.X - Const.pixelCenterX);
int y = (int)Math.Floor(point.Y - Const.pixelCenterY);
double xPrime = x + Const.pixelCenterX;
double yPrime = y + Const.pixelCenterY;
double rightWeight = (point.X - xPrime);
double bottomWeight = (point.Y - yPrime);
Color?p1 = SafeGetPixel(x, y);
Color?p2 = SafeGetPixel(x + 1, y);
Color?p3 = SafeGetPixel(x, y + 1);
Color?p4 = SafeGetPixel(x + 1, y + 1);
// Never blend with something outside the framebuffer
Color?p5 = ColorOperations.Blend(p2, p1, rightWeight);
Color?p6 = ColorOperations.Blend(p4, p3, rightWeight);
return(ColorOperations.Blend(p6, p5, bottomWeight));
}
