三角形的光栅化.doc

packageimportflash.display.Bitmap;importflash.display.BitmapData;importflash.display.Sprite;importflash.geom.Rectangle;publicclassDrawTriangleTestextendsSpriteprivatevartarget:BitmapData;privatevarrect:Rectangle;privatevarside:int;privatevarys:int;privatevartri_type:int;/初始值privatevarx0:int,x1:int,x2:int;privatevary0:int,y1:int,y2:int;privatevarxi:Number,yi:Number;privatevarxstart:int,xend:int;privatevarystart:int,yend:int;privatevarxl:Number,xr:Number;/左右斜边当前值/y每递增1时，左右斜边的增量privatevardxdyl:Number,dxdyr:Number;privatevardx:Number,dy:Number;privatevardyr:Number,dyl:Number;publicfunctionDrawTriangleTest()target=newBitmapData(400,400,true,0x0);this.addChild(newBitmap(target);rect=target.rect;varv0:Vector2D=newVector2D(50,10);varv1:Vector2D=newVector2D(10,150);varv2:Vector2D=newVector2D(300,300);drawTriangle(v0,v1,v2,0xFFFF0000);publicfunctiondrawTriangle(vt0:Vector2D,vt1:Vector2D,vt2:Vector2D,color:uint):voidvartemp1:Vector2D;vartri_type:int;vartemp:Number;/判断所有点是否在rect范围内if(vt0.yrect.y)&(vt1.yrect.y)&(vt2.yrect.height)&(vt1.yrect.height)&(vt2.yrect.height)|(vt0.xrect.x)&(vt1.xrect.x)&(vt2.xrect.width)&(vt1.xrect.width)&(vt2.xrect.width)return;/判断是否是一条线，如果是，则返回。if(vt0.x=vt1.x)&(vt1.x=vt2.x)|(vt0.y=vt1.y)&(vt1.y=vt2.y)return;/*调整vt0,vt1,vt2,让它们的y值从小到大*/if(vt1.yvt0.y)temp1=vt0,vt0=vt1,vt1=temp1;if(vt2.yvt0.y)temp1=vt0,vt0=vt2,vt2=temp1;if(vt2.yvt1.y)temp1=vt1,vt1=vt2,vt2=temp1;/*判断三角形的类型*/if(vt0.y=vt1.y)tri_type=Triangle3D.TRI_TYPE_FLAT_TOP;if(vt1.xvt0.x)temp1=vt0,vt0=vt1,vt1=temp1;elseif(vt1.y=vt2.y)tri_type=Triangle3D.TRI_TYPE_FLAT_BOTTOM;if(vt2.xvt1.x)temp1=vt1,vt1=vt2,vt2=temp1;elsetri_type=Triangle3D.TRI_TYPE_GENERAL;side=0;/转折后的斜边在哪一侧x0=vt0.x,y0=vt0.y;x1=vt1.x,y1=vt1.y;x2=vt2.x,y2=vt2.y;ys=y1;/转折点y坐标if(tri_type=Triangle3D.TRI_TYPE_FLAT_TOP|tri_type=Triangle3D.TRI_TYPE_FLAT_BOTTOM)if(tri_type=Triangle3D.TRI_TYPE_FLAT_TOP)dy=1/(y2-y0);dxdyl=(x2-x0)*dy;/左斜边倒数dxdyr=(x2-x1)*dy;/右斜边倒数/y0小于视窗顶部y坐标，调整左斜边和右斜边当前值,y值开始值if(y0rect.y)dy=(rect.y-y0);xl=dxdyl*dy+x0;xr=dxdyr*dy+x1;ystart=rect.y;else/注意平顶和平底这里的区别xl=x0;xr=x1;ystart=y0;else/平底三角形dy=1/(y1-y0);dxdyl=(x1-x0)*dy;dxdyr=(x2-x0)*dy;if(y0视窗高度时，大于rect.height部分就不用画出了if(yend=y2)rect.height)yend=rect.height;/x值需要裁剪的情况if(x0rect.width)|(x1rect.width)|(x2rect.width)for(yi=ystart;yi=yend;yi+)xstart=xl;xend=xr;/初始值需要裁剪if(xstartrect.width)xend=rect.width;/这里可以使用target.fillRect(newRectangle(xstart,yi,(xend-xstart),1),color);/但以后我们添加颜色插值时，还是必须单独绘制每个像素。/绘制扫描线for(xi=xstart;xi=xend;xi+)target.setPixel32(xi,yi,color);/y每增加1时,xl和xr分别加上他们的递增量xl+=dxdyl;xr+=dxdyr;else/不需要裁剪的情况for(yi=ystart;yi=yend;yi+)xstart=xl,xend=xr;for(xi=xstart;xirect.height)yend=rect.height;if(y1rect.y)/由于y0dxdyl)/交换斜边temp=dxdyl,dxdyl=dxdyr,dxdyr=temp;temp=xl,xl=xr,xr=temp;temp=x1,x1=x2,x2=temp;temp=y1,y1=y2,y2=temp;side=1;elseif(y0rect.y)dyl=1/(y1-y0);dxdyl=(x1-x0)*dyl;dyr=1/(y2-y0);dxdyr=(x2-x0)*dyr;dy=(rect.y-y0);xl=dxdyl*dy+x0;xr=dxdyr*dy+x0;ystart=rect.y;if(dxdyrdxdyl)temp=dxdyl,dxdyl=dxdyr,dxdyr=temp;temp=xl,xl=xr,xr=temp;temp=x1,x1=x2,x2=temp;temp=y1,y1=y2,y2=temp;side=1;else/y值都大于rect.ydyl=1/(y1-y0);dxdyl=(x1-x0)*dyl;dyr=1/(y2-y0);dxdyr=(x2-x0)*dyr;xl=x0;xr=x0;ystart=y0;if(dxdyrdxdyl)temp=dxdyl,dxdyl=dxdyr,dxdyr=temp;temp=xl,xl=xr,xr=temp;temp=x1,x1=x2,x2=temp;temp=y1,y1=y2,y2=temp;side=1;/x需要裁剪if(x0rect.width)|(x1rect.width)|(x2rect.width)for(yi=ystart;yi=yend;yi+)xstart=xl,xend=xr;if(xstartrect.width)xend=rect.width;for(xi=xstart;xi=xend;xi+)target.setPixel32(xi,yi,color);xl+=dxdyl;xr+=dxdyr;/转折点if(yi=ys)if(side=0)dyl=1/(y2-y1);dxdyl=(x2-x1)*dyl;xl=x1;xl+=dxdyl;elsedyr=1/(y1-y2);dxdyr=(x1-x2)*dyr;xr=x2;xr+=dxdyr;else/不需要裁剪for(yi=ystart;yi=yend;yi+)xstart=xl,xend=xr;for(xi=xstart;xi=xend;xi+)target.setPixel32(xi,yi,color);xl+=dxdyl;xr+=dxdyr;if(yi=ys)if(side=0)dyl=1/(y2-y1);dxdyl=(x2-x1)*dyl;xl=x1;xl+=dxdyl;elsedyr=1/(y1-y2);dxdyr=(x1-x2)*dyr;xr=x2;xr+=dxdyr;classVector2Dpublicvarx:Number;publicvary:Num