📄 2.3.2 扫描线填色算法.htm
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<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>float f_temp;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>i_temp=x.y_top; x.y_top=y.y_top; y.y_top=i_temp;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>f_temp=x.x_int; x.x_int=y.x_int; y.x_int=f_temp;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>i_temp=x.delta_y; x.delta=y.delta_y; y.delta_y=i_temp;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>f_temp=x.x_change_per_scan; x. x_change_per_scan=y.
x_change_per_scan; y.x.</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>change_per_scan=f_temp;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>}</FONT></P></BLOCKQUOTE>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify> </P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>void sort_on_x(entry, first_s)</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>int entry, first_s;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>{</FONT></P>
<BLOCKQUOTE>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>while((entry > first_s) && (sides[entry]. x_int <
sides[entry-1]. x_int))</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial> {</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
swap (sides[entry], sides[entry-1]);</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
entry - -;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>}</FONT></P></BLOCKQUOTE>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>}</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>void process_x_intersections(scan, first_s, last_s)</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>int scan, first_s, last_s;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>{</FONT></P>
<BLOCKQUOTE>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>int k;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>x_int_cout=0;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>for(k=first_s; k<last_s+1; k++)</FONT></P>
<BLOCKQUOTE>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>{</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>if(sides[k]. delta_y >0) {</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
x_int_count ++;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
sort_on_x(k, first_s);</FONT></P>
<P style="MARGIN-TOP: -1px; MARGIN-BOTTOM: -1px" align=justify><FONT
face=Arial>}</FONT></P></BLOCKQUOTE>
<P style="MARGIN-TOP: -1px; MARGIN-BOTTOM: -1px" align=justify><FONT
face=Arial>}</FONT></P></BLOCKQUOTE>
<P style="MARGIN-TOP: -1px; MARGIN-BOTTOM: -1px" align=justify><FONT
face=Arial>}</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify> </P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>void draw_lines(scan, x_int_count, index)</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>int scan, x_int_count, index;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>{</FONT></P>
<BLOCKQUOTE>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>int k, x, x1, x2;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>for (k=1; k< (int) (x_int_count/2+1.5); k++)</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>{</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
while(sides[index]. delta_y = = 0) index ++;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
x1=(int)(sides[index]. x_int +0.5);</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
index ++;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
while(sides[index].delta_y = = 0) index ++;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
x2 = (int) (sides [index]. x_int +0.5);</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
move((short)x1, (short)scan);</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
line((short)x2, (short)scan, status);</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
index ++;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>}</FONT></P></BLOCKQUOTE>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>}</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>void update_sides_list( )</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>{</FONT></P>
<BLOCKQUOTE>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>int k;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>for (k=first_s; k<last_s +1; k++)</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial> {</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
if(sides[k].delta_y >0)</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
{</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
sides[k].delta_y - -;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
sides[k]. x_int - = sides[k]. x_change_per_scan;</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
}</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial> }</FONT></P></BLOCKQUOTE>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>}</FONT></P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify> </P>
<P style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px" align=justify><FONT
face=Arial>
</FONT>程序<FONT face=Arial>2.3.1 </FONT>扫描线填色程序</P></BLOCKQUOTE>
<P align=justify><SUP><SPAN style="LETTER-SPACING: 1px"><FONT face=楷体_GB2312
size=4>1、sort_on_bigger_y子程序的主要功能是按照输入的多边形，建立起活性边表。操作步骤是：对每条边加以判断：如非水平边则调用put_in_side_list子程序放入活性边来；如是水平边则直接画出。</FONT></SPAN></SUP></P>
<P align=justify><SUP><SPAN style="LETTER-SPACING: 1px"><FONT face=楷体_GB2312
size=4>2、put_in_sides_list子程序的主要功能是将一条边存入活性边表之内。操作步骤是：对该边判别是否左顶点或右顶点，如果将入边之终点删去，按照y_top的大小在活性边表中找到该点的合适位置，在该边的位置中填入数据。</FONT></SPAN></SUP></P>
<P align=justify><SUP><SPAN style="LETTER-SPACING: 1px"><FONT face=楷体_GB2312
size=4>3、update_first_and_last子程序的主要功能是刷新活性边表的first和last两根指针的所指位置，以保证指针指出激活边的范围。</FONT></SPAN></SUP></P>
<P align=justify><SUP><SPAN style="LETTER-SPACING: 1px"><FONT face=楷体_GB2312
size=4>4、process_x_intersections子程序的主要功能是对活性边表中的激活边（即位于first和last之间的，并且? y?
0的边）按照x_int的大小排序。操作步骤是：从first到last，对每一根? y?
0的边，调用sort_on_x子程序排入活性边表中合适位置。</FONT></SPAN></SUP></P>
<P align=justify><SUP><SPAN style="LETTER-SPACING: 1px"><FONT face=楷体_GB2312
size=4>5、sort_on_x子程序主要功能是将一条边side[entry]，在活性边表的first到entry之间按x_int的大小插入合适位置。操作步骤是：检查位于entry的边的x_int是否小于位置entry-1的边的x_int，如是，调用swap子程序交换两条边的彼此位置。</FONT></SPAN></SUP></P>
<P align=justify><SUP><SPAN style="LETTER-SPACING: 1px"><FONT face=楷体_GB2312
size=4>6、swap子程序的主要功能是交换活性边表中两条相邻位置边的彼此位置。</FONT></SPAN></SUP></P>
<P align=justify><SUP><SPAN style="LETTER-SPACING: 1px"><FONT face=楷体_GB2312
size=4>7、draw_lines子程序的主要功能是在一条扫描线位于多边形内的部分，填上指定的色彩。操作步骤是：在活性边表的激活边范围内，依次取出Δy¹
0两边的x_int，作为两个端点（x1, scan），(x2, scan)，画一条水平线。</FONT></SPAN></SUP></P>
<P align=justify><SUP><SPAN style="LETTER-SPACING: 1px"><FONT face=楷体_GB2312
size=4>8、update_sides_list子程序的主要功能是刷新活性边表内激活边的值：Δy=Dy-1</FONT></SPAN></SUP></P>
<P align=justify><SUP><SPAN style="LETTER-SPACING: 1px"><FONT face=楷体_GB2312
size=4> x_int=x_int_x_chang_per_scan；</FONT></SPAN></SUP></P>
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