Add support for "squashing" the billboarding of individual 3D cloud sprites, to allow thin layers of stratus to be generated by large textures.

simgear/scene/sky/CloudShaderGeometry.cxx

@@ -116,7 +116,7 @@ void CloudShaderGeometry::drawImplementation(RenderInfo& renderInfo) const
                            (GLfloat) t.cloud_height };
         extensions->glVertexAttrib3fv(USR_ATTR_1, ua1 );
         extensions->glVertexAttrib3fv(USR_ATTR_2, ua2 );
-        glColor4f(t.position.x(), t.position.y(), t.position.z(), 1.0);
+        glColor4f(t.position.x(), t.position.y(), t.position.z(), zscale);
         _geometry->draw(renderInfo);
     }
 }

simgear/scene/sky/CloudShaderGeometry.hxx

@@ -52,8 +52,8 @@ class CloudShaderGeometry : public osg::Drawable
             setUseDisplayList(false); 
         }
 
-        CloudShaderGeometry(int vx, int vy, float width, float height) :
+        CloudShaderGeometry(int vx, int vy, float width, float height, float zsc) :
-            varieties_x(vx), varieties_y(vy)
+            varieties_x(vx), varieties_y(vy), zscale(zsc)
         { 
             setUseDisplayList(false); 
             float x = width/2.0f;
@@ -107,13 +107,14 @@ class CloudShaderGeometry : public osg::Drawable
             _geometry = geometry;
         }
         
-    void addSprite(const SGVec3f& p, int tx, int ty, float w, float h,
+        void addSprite(const SGVec3f& p, int tx, int ty, float w, float h,
-                   float s, float cull, float cloud_height);
+                       float s, float cull, float cloud_height);
                 
         osg::ref_ptr<osg::Drawable> _geometry;
 
         int varieties_x;
         int varieties_y;
+        float zscale;
         
         // Bounding box extents.
         osg::BoundingBox _bbox;

simgear/scene/sky/newcloud.cxx

@@ -83,6 +83,7 @@ SGNewCloud::SGNewCloud(const SGPath &texture_root, const SGPropertyNode *cld_def
     num_textures_x = cld_def->getIntValue("num-textures-x", 4);
     num_textures_y = cld_def->getIntValue("num-textures-y", 4);
     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");
 
     // Create a new Effect for the texture, if required.
@@ -165,7 +166,7 @@ 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);
+    CloudShaderGeometry* sg = new CloudShaderGeometry(num_textures_x, num_textures_y, max_width, max_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

simgear/scene/sky/newcloud.hxx

@@ -70,6 +70,7 @@ private:
         double min_sprite_height;
         double max_sprite_height;
         double bottom_shade;
+        double zscale;
         int num_sprites;
         int num_textures_x;
         int num_textures_y;