diff options
| -rw-r--r-- | generic/tkbltGrElemLine.C | 86 |
1 files changed, 79 insertions, 7 deletions
diff --git a/generic/tkbltGrElemLine.C b/generic/tkbltGrElemLine.C index f8ec8f7..9e3f39a 100644 --- a/generic/tkbltGrElemLine.C +++ b/generic/tkbltGrElemLine.C @@ -1427,6 +1427,71 @@ void LineElement::mergePens(LineStyle **styleMap) } } +#define CLIP_TOP (1<<0) +#define CLIP_BOTTOM (1<<1) +#define CLIP_RIGHT (1<<2) +#define CLIP_LEFT (1<<3) + +int LineElement::outCode(Region2d *extsPtr, Point2d *p) +{ + int code =0; + if (p->x > extsPtr->right) + code |= CLIP_RIGHT; + else if (p->x < extsPtr->left) + code |= CLIP_LEFT; + + if (p->y > extsPtr->bottom) + code |= CLIP_BOTTOM; + else if (p->y < extsPtr->top) + code |= CLIP_TOP; + + return code; +} + +int LineElement::clipSegment(Region2d *extsPtr, int code1, int code2, + Point2d *p, Point2d *q) +{ + int inside = ((code1 | code2) == 0); + int outside = ((code1 & code2) != 0); + + /* + * In the worst case, we'll clip the line segment against each of the four + * sides of the bounding rectangle. + */ + while ((!outside) && (!inside)) { + if (code1 == 0) { + Point2d *tmp; + int code; + + /* Swap pointers and out codes */ + tmp = p, p = q, q = tmp; + code = code1, code1 = code2, code2 = code; + } + if (code1 & CLIP_LEFT) { + p->y += (q->y - p->y) * + (extsPtr->left - p->x) / (q->x - p->x); + p->x = extsPtr->left; + } else if (code1 & CLIP_RIGHT) { + p->y += (q->y - p->y) * + (extsPtr->right - p->x) / (q->x - p->x); + p->x = extsPtr->right; + } else if (code1 & CLIP_BOTTOM) { + p->x += (q->x - p->x) * + (extsPtr->bottom - p->y) / (q->y - p->y); + p->y = extsPtr->bottom; + } else if (code1 & CLIP_TOP) { + p->x += (q->x - p->x) * + (extsPtr->top - p->y) / (q->y - p->y); + p->y = extsPtr->top; + } + code1 = outCode(extsPtr, p); + + inside = ((code1 | code2) == 0); + outside = ((code1 & code2) != 0); + } + return (!inside); +} + void LineElement::saveTrace(int start, int length, MapInfo* mapPtr) { bltTrace* tracePtr = new bltTrace; @@ -1479,18 +1544,24 @@ void LineElement::mapTraces(MapInfo *mapPtr) graphPtr_->extents(&exts); int count = 1; + int code1 = outCode(&exts, mapPtr->screenPts); Point2d* p = mapPtr->screenPts; Point2d* q = p + 1; int start; int ii; for (ii=1; ii<mapPtr->nScreenPts; ii++, p++, q++) { - // Save the coordinates of the last point before clipping. - Point2d originalq = *q; - int broken = BROKEN_TRACE(ops->penDir, p->x, q->x); - LineRectClipResult clipresult = lineRectClip(&exts, p, q); + Point2d s; + s.x = 0; + s.y = 0; + int code2 = outCode(&exts, q); + // Save the coordinates of the last point, before clipping + if (code2 != 0) + s = *q; - if (broken || clipresult == CLIP_OUTSIDE) { + int broken = BROKEN_TRACE(ops->penDir, p->x, q->x); + int offscreen = clipSegment(&exts, code1, code2, p, q); + if (broken || offscreen) { // The last line segment is either totally clipped by the plotting // area or the x-direction is wrong, breaking the trace. Either // way, save information about the last trace (if one exists), @@ -1508,13 +1579,14 @@ void LineElement::mapTraces(MapInfo *mapPtr) // If the last point is clipped, this means that the trace is // broken after this point. Restore the original coordinate // (before clipping) after saving the trace. - if (clipresult & CLIP_Q) { + if (code2 != 0) { start = ii - (count - 1); saveTrace(start, count, mapPtr); - mapPtr->screenPts[ii] = originalq; + mapPtr->screenPts[ii] = s; count = 1; } } + code1 = code2; } if (count > 1) { start = ii - count; |