Files
OpenMaidEngine/engine/Age.Engine/Model/SoftwareAffineRasterizer.cs
2026-07-11 15:31:56 -04:00

116 lines
5.9 KiB
C#

namespace Age.Engine.Model;
/// <summary>Nearest-neighbour inverse-mapped RGBA8 affine compositor used by the Godot host and pure tests.</summary>
public static class SoftwareAffineRasterizer
{
public static void BlitRgba(byte[] dst, int dstW, int dstH, byte[] src, int srcW, int srcH,
int srcX, int srcY, int width, int height, Affine2D localToDest,
long tint, float tintStrength, float opacity, bool multiplyTint = false)
{
if (width <= 0 || height <= 0) return;
int istr = (int)(System.Math.Clamp(tintStrength, 0f, 1f) * 255);
int ia = (int)(System.Math.Clamp(opacity, 0f, 1f) * 255);
if (ia == 0) return;
int tr=(int)(tint>>16&255), tg=(int)(tint>>8&255), tb=(int)(tint&255);
if (TryIntegerTranslation(localToDest, out int tx, out int ty))
{
BlitTranslated(dst, dstW, dstH, src, srcW, srcX, srcY, width, height,
tx, ty, tr, tg, tb, istr, ia, multiplyTint);
return;
}
if (!localToDest.TryInverse(out var inv)) return;
Bounds(localToDest, width, height, dstW, dstH, out int x0, out int y0, out int x1, out int y1);
for (int y=y0; y<y1; y++) for (int x=x0; x<x1; x++)
{
var p = inv.Apply(x + 0.5, y + 0.5);
int u=(int)System.Math.Floor(p.X), v=(int)System.Math.Floor(p.Y);
if ((uint)u >= (uint)width || (uint)v >= (uint)height) continue;
int si=((srcY+v)*srcW+(srcX+u))*4, di=(y*dstW+x)*4;
int sa=src[si+3]*ia/255; if(sa==0) continue;
int sr=multiplyTint ? src[si]*tr/255 : (src[si]*(255-istr)+tr*istr)/255;
int sg=multiplyTint ? src[si+1]*tg/255 : (src[si+1]*(255-istr)+tg*istr)/255;
int sb=multiplyTint ? src[si+2]*tb/255 : (src[si+2]*(255-istr)+tb*istr)/255;
Blend(dst,di,sr,sg,sb,sa);
}
}
public static void FillRgba(byte[] dst, int dstW, int dstH, int width, int height,
Affine2D localToDest, long color, float opacity)
{
if (width <= 0 || height <= 0) return;
int a=(int)(System.Math.Clamp(opacity,0f,1f)*255); if(a==0)return;
int r=(int)(color>>16&255),g=(int)(color>>8&255),b=(int)(color&255);
if (TryIntegerTranslation(localToDest, out int tx, out int ty))
{
FillTranslated(dst, dstW, dstH, width, height, tx, ty, r, g, b, a);
return;
}
if (!localToDest.TryInverse(out var inv)) return;
Bounds(localToDest,width,height,dstW,dstH,out int x0,out int y0,out int x1,out int y1);
for(int y=y0;y<y1;y++)for(int x=x0;x<x1;x++){
var p=inv.Apply(x+.5,y+.5);
if(p.X>=0&&p.X<width&&p.Y>=0&&p.Y<height) Blend(dst,(y*dstW+x)*4,r,g,b,a);
}
}
private static bool TryIntegerTranslation(Affine2D m, out int tx, out int ty)
{
tx = ty = 0;
if (m.XX != 1 || m.XY != 0 || m.YX != 0 || m.YY != 1 ||
m.TX != System.Math.Truncate(m.TX) || m.TY != System.Math.Truncate(m.TY) ||
m.TX < int.MinValue || m.TX > int.MaxValue || m.TY < int.MinValue || m.TY > int.MaxValue)
return false;
tx = (int)m.TX;
ty = (int)m.TY;
return true;
}
private static void BlitTranslated(byte[] dst, int dstW, int dstH, byte[] src, int srcW,
int srcX, int srcY, int width, int height, int tx, int ty,
int tr, int tg, int tb, int istr, int ia, bool multiplyTint)
{
int x0 = System.Math.Max(0, tx), y0 = System.Math.Max(0, ty);
int x1 = (int)System.Math.Min(dstW, (long)tx + width);
int y1 = (int)System.Math.Min(dstH, (long)ty + height);
for (int y = y0; y < y1; y++)
{
int v = y - ty;
for (int x = x0; x < x1; x++)
{
int u = x - tx;
int si = ((srcY + v) * srcW + (srcX + u)) * 4, di = (y * dstW + x) * 4;
int sa = src[si + 3] * ia / 255;
if (sa == 0) continue;
int sr = multiplyTint ? src[si] * tr / 255 : (src[si] * (255 - istr) + tr * istr) / 255;
int sg = multiplyTint ? src[si + 1] * tg / 255 : (src[si + 1] * (255 - istr) + tg * istr) / 255;
int sb = multiplyTint ? src[si + 2] * tb / 255 : (src[si + 2] * (255 - istr) + tb * istr) / 255;
Blend(dst, di, sr, sg, sb, sa);
}
}
}
private static void FillTranslated(byte[] dst, int dstW, int dstH, int width, int height,
int tx, int ty, int r, int g, int b, int a)
{
int x0 = System.Math.Max(0, tx), y0 = System.Math.Max(0, ty);
int x1 = (int)System.Math.Min(dstW, (long)tx + width);
int y1 = (int)System.Math.Min(dstH, (long)ty + height);
for (int y = y0; y < y1; y++)
for (int x = x0; x < x1; x++)
Blend(dst, (y * dstW + x) * 4, r, g, b, a);
}
private static void Bounds(Affine2D m,int w,int h,int dw,int dh,out int x0,out int y0,out int x1,out int y1)
{
var a=m.Apply(0,0);var b=m.Apply(w,0);var c=m.Apply(0,h);var d=m.Apply(w,h);
x0=System.Math.Max(0,(int)System.Math.Floor(System.Math.Min(System.Math.Min(a.X,b.X),System.Math.Min(c.X,d.X))));
y0=System.Math.Max(0,(int)System.Math.Floor(System.Math.Min(System.Math.Min(a.Y,b.Y),System.Math.Min(c.Y,d.Y))));
x1=System.Math.Min(dw,(int)System.Math.Ceiling(System.Math.Max(System.Math.Max(a.X,b.X),System.Math.Max(c.X,d.X))));
y1=System.Math.Min(dh,(int)System.Math.Ceiling(System.Math.Max(System.Math.Max(a.Y,b.Y),System.Math.Max(c.Y,d.Y))));
}
private static void Blend(byte[] d,int i,int r,int g,int b,int a){
d[i]=(byte)((r*a+d[i]*(255-a))/255);d[i+1]=(byte)((g*a+d[i+1]*(255-a))/255);
d[i+2]=(byte)((b*a+d[i+2]*(255-a))/255);d[i+3]=(byte)System.Math.Min(255,d[i+3]+a);
}
}