(original) (raw)

Jim,

FYI, I am working on optimizing the 2 hotspot methods annotated by oprofile (see specific emails) :
- ScanLineIterator.next() ~ 35%
- Renderer.endRendering(...) ~ 20%

I think that the ScanLineIterator class is no more useful and could be merged into Renderer directly: I try to optimize these 2 code paths (crossing / crossing -> alpha) but it seems quite difficult as I must understand hotspot optimizations (assembler code)...


For now I want to keep pisces in Java code as hotspot is efficient enough and probably the algorithm can be reworked a bit;
few questions:
- should edges be sorted by Ymax ONCE to avoid complete edges traversal to count crossings for each Y value:

 156 if ((bucketcount & 0x1) != 0) {  
 157 int newCount = 0;  
 158 for (int i = 0, ecur; i < count; i++) {  
 159 ecur = ptrs\[i\];  
 160 if (\_edgesInt\[ecur + YMAX\] > cury) {  
 161 ptrs\[newCount++\] = ecur;  
 162 }  
 163 }  
 164 count = newCount;  
 165 }

 202 for (int i = 0, ecur, j; i < count; i++) {  
 203 ecur = ptrs[i];
 204 curx = _edges[ecur /* + CURX */];
 205 _edges[ecur /* + CURX */] = curx + _edges[ecur + SLOPE];
 206
 207 cross = ((int) curx) << 1;
 208 if (_edgesInt[ecur + OR] != 0 /* > 0 */) {
 209 cross |= 1;
 210 }

 674 int lowx = crossings[0] >> 1;
 675 int highx = crossings[numCrossings - 1] >> 1;

 689 for (int i = 0; i < numCrossings; i++) {
 690 int curxo = crossings[i];
 691 int curx = curxo >> 1;

- last x pixel processing: could you explain me ?
 712 int pix_xmax = x1 >> SUBPIXEL_LG_POSITIONS_X;
 713 int tmp = (x0 & SUBPIXEL_MASK_X);
 714 alpha[pix_x] += SUBPIXEL_POSITIONS_X - tmp;
 715 alpha[pix_x + 1] += tmp;
 716 tmp = (x1 & SUBPIXEL_MASK_X);
 717 alpha[pix_xmax] -= SUBPIXEL_POSITIONS_X - tmp;
 718 alpha[pix_xmax + 1] -= tmp;