Further enhancements/bug fixes to the 3D clouds:

1) Default values for [min|max]_[cloud|sprite]_[width|height] changed to be
   more logical.

2) Cloud bounding box expanded slightly to ensure they aren't over-culled

3) Cloud location now defines the _base_ of the cloud.

4) Sprites that would extend below the bottom of the cloud are now shifted
   upwards to ensure no cloud appears below the base.

simgear/scene/sky/cloud.cxx

@@ -675,138 +675,142 @@ bool SGCloudLayer::repaint( const SGVec3f& fog_color ) {
 bool SGCloudLayer::reposition( const SGVec3f& p, const SGVec3f& up, double lon, double lat,
         		       double alt, double dt )
 {
-    // combine p and asl (meters) to get translation offset
-    osg::Vec3 asl_offset(toOsg(up));
-    asl_offset.normalize();
-    if ( alt <= layer_asl ) {
-        asl_offset *= layer_asl;
-    } else {
-        asl_offset *= layer_asl + layer_thickness;
-    }
   
-    // cout << "asl_offset = " << asl_offset[0] << "," << asl_offset[1]
+    if (getCoverage() != SGCloudLayer::SG_CLOUD_CLEAR)
-    //      << "," << asl_offset[2] << endl;
+    {
-    asl_offset += toOsg(p);
+        // combine p and asl (meters) to get translation offset
-    // cout << "  asl_offset = " << asl_offset[0] << "," << asl_offset[1]
+        osg::Vec3 asl_offset(toOsg(up));
-    //      << "," << asl_offset[2] << endl;
+        asl_offset.normalize();
-
+        if ( alt <= layer_asl ) {
-    osg::Matrix T, LON, LAT;
+            asl_offset *= layer_asl;
-    // Translate to zero elevation
-    // Point3D zero_elev = current_view.get_cur_zero_elev();
-    T.makeTranslate( asl_offset );
-
-    // printf("  Translated to %.2f %.2f %.2f\n", 
-    //        zero_elev.x, zero_elev.y, zero_elev.z );
-
-    // Rotate to proper orientation
-    // printf("  lon = %.2f  lat = %.2f\n", 
-    //        lon * SGD_RADIANS_TO_DEGREES,
-    //        lat * SGD_RADIANS_TO_DEGREES);
-    LON.makeRotate(lon, osg::Vec3(0, 0, 1));
-
-    // xglRotatef( 90.0 - f->get_Latitude() * SGD_RADIANS_TO_DEGREES,
-    //             0.0, 1.0, 0.0 );
-    LAT.makeRotate(90.0 * SGD_DEGREES_TO_RADIANS - lat, osg::Vec3(0, 1, 0));
-
-    layer_transform->setMatrix( LAT*LON*T );
-
-    // The layers need to be drawn in order because they are
-    // translucent, but OSG transparency sorting doesn't work because
-    // the cloud polys are huge. However, the ordering is simple: the
-    // bottom polys should be drawn from high altitude to low, and the
-    // top polygons from low to high. The altitude can be used
-    // directly to order the polygons!
-    group_bottom->getStateSet()->setRenderBinDetails(-(int)layer_asl,
-                                                     "RenderBin");
-    group_top->getStateSet()->setRenderBinDetails((int)layer_asl,
-                                                  "RenderBin");
-    if ( alt <= layer_asl ) {
-      layer_root->setSingleChildOn(0);
-    } else if ( alt >= layer_asl + layer_thickness ) {
-      layer_root->setSingleChildOn(1);
-    } else {
-      layer_root->setAllChildrenOff();
-    }
-        
-
-    // now calculate update texture coordinates
-    SGGeod pos = SGGeod::fromRad(lon, lat);
-    if ( last_pos == SGGeod() ) {
-        last_pos = pos;
-    }
-
-    double sp_dist = speed*dt;
-    
-    
-    if ( lon != last_pos.getLongitudeRad() || lat != last_pos.getLatitudeRad() || sp_dist != 0 ) {
-        double course = SGGeodesy::courseDeg(last_pos, pos) * SG_DEGREES_TO_RADIANS, 
-            dist = SGGeodesy::distanceM(last_pos, pos);
-
-        // if start and dest are too close together,
-        // calc_gc_course_dist() can return a course of "nan".  If
-        // this happens, lets just use the last known good course.
-        // This is a hack, and it would probably be better to make
-        // calc_gc_course_dist() more robust.
-        if ( isnan(course) ) {
-            course = last_course;
         } else {
-            last_course = course;
+            asl_offset *= layer_asl + layer_thickness;
         }
 
-        // calculate cloud movement due to external forces
+        // cout << "asl_offset = " << asl_offset[0] << "," << asl_offset[1]
-        double ax = 0.0, ay = 0.0, bx = 0.0, by = 0.0;
+        //      << "," << asl_offset[2] << endl;
+        asl_offset += toOsg(p);
+        // cout << "  asl_offset = " << asl_offset[0] << "," << asl_offset[1]
+        //      << "," << asl_offset[2] << endl;
 
-        if (dist > 0.0) {
+        osg::Matrix T, LON, LAT;
-            ax = -cos(course) * dist;
+        // Translate to zero elevation
-            ay = sin(course) * dist;
+        // Point3D zero_elev = current_view.get_cur_zero_elev();
-        }
+        T.makeTranslate( asl_offset );
 
-        if (sp_dist > 0) {
+        // printf("  Translated to %.2f %.2f %.2f\n", 
-            bx = cos((180.0-direction) * SGD_DEGREES_TO_RADIANS) * sp_dist;
+        //        zero_elev.x, zero_elev.y, zero_elev.z );
-            by = sin((180.0-direction) * SGD_DEGREES_TO_RADIANS) * sp_dist;
-        }
 
+        // Rotate to proper orientation
+        // printf("  lon = %.2f  lat = %.2f\n", 
+        //        lon * SGD_RADIANS_TO_DEGREES,
+        //        lat * SGD_RADIANS_TO_DEGREES);
+        LON.makeRotate(lon, osg::Vec3(0, 0, 1));
 
-        double xoff = (ax + bx) / (2 * scale);
+        // xglRotatef( 90.0 - f->get_Latitude() * SGD_RADIANS_TO_DEGREES,
-        double yoff = (ay + by) / (2 * scale);
+        //             0.0, 1.0, 0.0 );
+        LAT.makeRotate(90.0 * SGD_DEGREES_TO_RADIANS - lat, osg::Vec3(0, 1, 0));
 
+        layer_transform->setMatrix( LAT*LON*T );
 
-//        const float layer_scale = layer_span / scale;
+        // The layers need to be drawn in order because they are
-
+        // translucent, but OSG transparency sorting doesn't work because
-        // cout << "xoff = " << xoff << ", yoff = " << yoff << endl;
+        // the cloud polys are huge. However, the ordering is simple: the
-        base[0] += xoff;
+        // bottom polys should be drawn from high altitude to low, and the
-
+        // top polygons from low to high. The altitude can be used
-        // the while loops can lead to *long* pauses if base[0] comes
+        // directly to order the polygons!
-        // with a bogus value.
+        group_bottom->getStateSet()->setRenderBinDetails(-(int)layer_asl,
-        // while ( base[0] > 1.0 ) { base[0] -= 1.0; }
+                                                         "RenderBin");
-        // while ( base[0] < 0.0 ) { base[0] += 1.0; }
+        group_top->getStateSet()->setRenderBinDetails((int)layer_asl,
-        if ( base[0] > -10.0 && base[0] < 10.0 ) {
+                                                      "RenderBin");
-            base[0] -= (int)base[0];
+        if ( alt <= layer_asl ) {
+          layer_root->setSingleChildOn(0);
+        } else if ( alt >= layer_asl + layer_thickness ) {
+          layer_root->setSingleChildOn(1);
         } else {
-            SG_LOG(SG_ASTRO, SG_DEBUG,
+          layer_root->setAllChildrenOff();
-                "Error: base = " << base[0] << "," << base[1] <<
-                " course = " << course << " dist = " << dist );
-            base[0] = 0.0;
         }
             
-        base[1] += yoff;
+
-        // the while loops can lead to *long* pauses if base[0] comes
+        // now calculate update texture coordinates
-        // with a bogus value.
+        SGGeod pos = SGGeod::fromRad(lon, lat);
-        // while ( base[1] > 1.0 ) { base[1] -= 1.0; }
+        if ( last_pos == SGGeod() ) {
-        // while ( base[1] < 0.0 ) { base[1] += 1.0; }
+            last_pos = pos;
-        if ( base[1] > -10.0 && base[1] < 10.0 ) {
+        }
-            base[1] -= (int)base[1];
+
-        } else {
+        double sp_dist = speed*dt;
-            SG_LOG(SG_ASTRO, SG_DEBUG,
+        
+        
+        if ( lon != last_pos.getLongitudeRad() || lat != last_pos.getLatitudeRad() || sp_dist != 0 ) {
+            double course = SGGeodesy::courseDeg(last_pos, pos) * SG_DEGREES_TO_RADIANS, 
+                dist = SGGeodesy::distanceM(last_pos, pos);
+
+            // if start and dest are too close together,
+            // calc_gc_course_dist() can return a course of "nan".  If
+            // this happens, lets just use the last known good course.
+            // This is a hack, and it would probably be better to make
+            // calc_gc_course_dist() more robust.
+            if ( isnan(course) ) {
+                course = last_course;
+            } else {
+                last_course = course;
+            }
+
+            // calculate cloud movement due to external forces
+            double ax = 0.0, ay = 0.0, bx = 0.0, by = 0.0;
+
+            if (dist > 0.0) {
+                ax = -cos(course) * dist;
+                ay = sin(course) * dist;
+            }
+
+            if (sp_dist > 0) {
+                bx = cos((180.0-direction) * SGD_DEGREES_TO_RADIANS) * sp_dist;
+                by = sin((180.0-direction) * SGD_DEGREES_TO_RADIANS) * sp_dist;
+            }
+
+
+            double xoff = (ax + bx) / (2 * scale);
+            double yoff = (ay + by) / (2 * scale);
+
+
+    //        const float layer_scale = layer_span / scale;
+
+            // cout << "xoff = " << xoff << ", yoff = " << yoff << endl;
+            base[0] += xoff;
+
+            // the while loops can lead to *long* pauses if base[0] comes
+            // with a bogus value.
+            // while ( base[0] > 1.0 ) { base[0] -= 1.0; }
+            // while ( base[0] < 0.0 ) { base[0] += 1.0; }
+            if ( base[0] > -10.0 && base[0] < 10.0 ) {
+                base[0] -= (int)base[0];
+            } else {
+                SG_LOG(SG_ASTRO, SG_DEBUG,
                     "Error: base = " << base[0] << "," << base[1] <<
                     " course = " << course << " dist = " << dist );
-            base[1] = 0.0;
+                base[0] = 0.0;
+            }
+
+            base[1] += yoff;
+            // the while loops can lead to *long* pauses if base[0] comes
+            // with a bogus value.
+            // while ( base[1] > 1.0 ) { base[1] -= 1.0; }
+            // while ( base[1] < 0.0 ) { base[1] += 1.0; }
+            if ( base[1] > -10.0 && base[1] < 10.0 ) {
+                base[1] -= (int)base[1];
+            } else {
+                SG_LOG(SG_ASTRO, SG_DEBUG,
+                        "Error: base = " << base[0] << "," << base[1] <<
+                        " course = " << course << " dist = " << dist );
+                base[1] = 0.0;
+            }
+
+            // cout << "base = " << base[0] << "," << base[1] << endl;
+
+            setTextureOffset(base);
+            last_pos = pos;
         }
-
-        // cout << "base = " << base[0] << "," << base[1] << endl;
-
-        setTextureOffset(base);
-        last_pos = pos;
     }
 
     layer3D->reposition( p, up, lon, lat, dt, layer_asl, speed, direction);

simgear/scene/sky/newcloud.cxx

@@ -72,16 +72,17 @@ double SGNewCloud::sprite_density = 1.0;
 SGNewCloud::SGNewCloud(const SGPath &texture_root, const SGPropertyNode *cld_def)
 {
     min_width = cld_def->getDoubleValue("min-cloud-width-m", 500.0);
-    max_width = cld_def->getDoubleValue("max-cloud-width-m", 1000.0);
+    max_width = cld_def->getDoubleValue("max-cloud-width-m", min_width*2);
-    min_height = cld_def->getDoubleValue("min-cloud-height-m", min_width);
+    min_height = cld_def->getDoubleValue("min-cloud-height-m", 400.0);
-    max_height = cld_def->getDoubleValue("max-cloud-height-m", max_width);
+    max_height = cld_def->getDoubleValue("max-cloud-height-m", min_height*2);
     min_sprite_width = cld_def->getDoubleValue("min-sprite-width-m", 200.0);
-    max_sprite_width = cld_def->getDoubleValue("max-sprite-width-m", min_sprite_width);
+    max_sprite_width = cld_def->getDoubleValue("max-sprite-width-m", min_sprite_width*1.5);
-    min_sprite_height = cld_def->getDoubleValue("min-sprite-height-m", min_sprite_width);
+    min_sprite_height = cld_def->getDoubleValue("min-sprite-height-m", 150);
-    max_sprite_height = cld_def->getDoubleValue("max-sprite-height-m", max_sprite_width);
+    max_sprite_height = cld_def->getDoubleValue("max-sprite-height-m", min_sprite_height*1.5);
     num_sprites = cld_def->getIntValue("num-sprites", 20);
     num_textures_x = cld_def->getIntValue("num-textures-x", 4);
     num_textures_y = cld_def->getIntValue("num-textures-y", 4);
+    height_map_texture = cld_def->getBoolValue("height-map-texture", false);
     bottom_shade = cld_def->getDoubleValue("bottom-shade", 1.0);
     zscale = cld_def->getDoubleValue("z-scale", 1.0);
     texture = cld_def->getStringValue("texture", "cl_cumulus.png");
@@ -166,7 +167,11 @@ osg::ref_ptr<EffectGeode> SGNewCloud::genCloud() {
     
     osg::ref_ptr<EffectGeode> geode = new EffectGeode;
         
-    CloudShaderGeometry* sg = new CloudShaderGeometry(num_textures_x, num_textures_y, max_width, max_height, zscale);
+    CloudShaderGeometry* sg = new CloudShaderGeometry(num_textures_x, 
+                                                      num_textures_y, 
+                                                      max_width + max_sprite_width, 
+                                                      max_height + max_sprite_height, 
+                                                      zscale);
     
     // Determine how big this specific cloud instance is. Note that we subtract
     // the sprite size because the width/height is used to define the limits of
@@ -186,20 +191,22 @@ osg::ref_ptr<EffectGeode> SGNewCloud::genCloud() {
         // Determine the position of the sprite. Rather than being completely random,
         // we place them on the surface of a distorted sphere. However, we place
         // the first sprite in the center of the sphere (and at maximum size) to
-	// ensure good coverage and reduce the chance of there being "holes" in our
+	      // ensure good coverage and reduce the chance of there being "holes" in the
+	      // middle of our cloud. Also note that (0,0,0) defines the _bottom_ of the
+	      // cloud, not the middle. 
 
         float x, y, z;
 
         if (i == 0) {
             x = 0;
             y = 0;
-            z = 0;
+            z = height * 0.5;
         } else {
             double theta = sg_random() * SGD_2PI;
             double elev  = sg_random() * SGD_PI;
             x = width * cos(theta) * 0.5f * sin(elev);
             y = width * sin(theta) * 0.5f * sin(elev);
-            z = height * cos(elev) * 0.5f;
+            z = height * cos(elev) * 0.5f + height * 0.5f;
         }
         
         // Determine the height and width as scaling factors on the minimum size (used to create the quad).
@@ -218,16 +225,30 @@ osg::ref_ptr<EffectGeode> SGNewCloud::genCloud() {
             sprite_height = 1.0f + (max_sprite_height - min_sprite_height) / min_sprite_height;
         }
         
+        // If the center of the sprite is less than half the sprite heightthe sprite will extend 
+        // below the bottom of the cloud and must be shifted upwards. This is particularly important 
+        // for cumulus clouds which have a very well defined base.
+        if (z < 0.5f * sprite_height * min_sprite_height)
+        {
+            z = 0.5f * sprite_height * min_sprite_height;          
+        }        
+
         // Determine the sprite texture indexes.
         int index_x = (int) floor(sg_random() * num_textures_x);
         if (index_x == num_textures_x) { index_x--; }
                 
-        // The y index depends on the positing of the sprite within the cloud.
+        int index_y = (int) floor(sg_random() * num_textures_y);
-        // This allows cloud designers to have particular sprites for the base
+        
-        // and tops of the cloud.
+        if (height_map_texture) {
-        int index_y = (int) floor((z / height + 0.5f) * num_textures_y);
+          // The y index depends on the position of the sprite within the cloud.
+          // This allows cloud designers to have particular sprites for the base
+          // and tops of the cloud.
+          index_y = (int) floor((z / height + 0.5f) * num_textures_y);
+        }
+        
         if (index_y == num_textures_y) { index_y--; }
         
+        
         sg->addSprite(SGVec3f(x, y, z), 
                     index_x, 
                     index_y, 

simgear/scene/sky/newcloud.hxx

@@ -71,6 +71,7 @@ private:
         double max_sprite_height;
         double bottom_shade;
         double zscale;
+        bool height_map_texture;
         int num_sprites;
         int num_textures_x;
         int num_textures_y;