[Kstars-devel] branches/kstars/hdevalence/kstars/kstars

[Henry de Valence]

SVN commit 1153457 by hdevalence:

Implement proper clipping for the GL painter's drawSkyPolyline()
function. It's somewhat slower than no clipping, but on the other
hand it is actually correct and produces no wierd garbage.

In particular the gnomonic projection works totally correctly.

CCMAIL:kstars-devel at kde.org


 M  +36 -11    skyglpainter.cpp  


--- branches/kstars/hdevalence/kstars/kstars/skyglpainter.cpp #1153456:1153457
@@ -263,26 +263,51 @@
     }
 }
 
+//This implementation is *correct* but slow.
 void SkyGLPainter::drawSkyPolyline(LineList* list, SkipList* skipList, LineListLabel* label)
 {
     glDisable(GL_TEXTURE_2D);
+    glBegin(GL_LINE_STRIP);
     SkyList *points = list->points();
-    bool isVisible = false;
-    bool isVisibleLast = false;
-    glBegin(GL_LINE_STRIP);
-    for(int i = 0; i < points->size(); ++i) {
-        SkyPoint* p = points->at(i);
-        Vector2f vec = m_sm->toScreenVec(p,true,&isVisible);
+    bool isVisible, isVisibleLast;
+    Vector2f oLast = m_sm->toScreenVec(points->first(), true, &isVisibleLast);
+    if( isVisibleLast ) { glVertex2fv(oLast.data()); }
+
+    for(int i = 1; i < points->size(); ++i) {
+        Vector2f oThis = m_sm->toScreenVec( points->at(i), true, &isVisible);
+
         bool doSkip = (skipList ? skipList->skip(i) : false);
-        if( doSkip ) {
+        //This tells us whether we need to end the current line or whether we
+        //are to keep drawing into it. If we skip, then we are going to have to end.
+        bool shouldEnd = doSkip;
+
+        if( !doSkip ) {
+            if( isVisible && isVisibleLast ) {
+                glVertex2fv(oThis.data());
+                if( label ) {
+                    label->updateLabelCandidates(oThis.x(), oThis.y(), list, i);
+                }
+            } else if( isVisibleLast ) {
+                Vector2f oMid = m_sm->clipLineVec( points->at(i-1), points->at(i) );
+                glVertex2fv(oMid.data());
+                //If the last point was visible but this one isn't we are at
+                //the end of a strip, so we need to end
+                shouldEnd = true;
+            } else if( isVisible ) {
+                Vector2f oMid = m_sm->clipLineVec( points->at(i), points->at(i-1) );
+                glVertex2fv(oMid.data());
+                glVertex2fv(oThis.data());
+            }
+        }
+
+        if(shouldEnd) {
             glEnd();
             glBegin(GL_LINE_STRIP);
+            if( isVisible ) {
+                glVertex2fv(oThis.data());
         }
-        glVertex2fv(vec.data());
-        //FIXME: check whether this actually works when the labels are fixed.
-        if ( isVisible && isVisibleLast && label ) {
-            label->updateLabelCandidates(vec[0], vec[1], list, i);
         }
+
         isVisibleLast = isVisible;
     }
     glEnd();