X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;f=simgear%2Fscene%2Fsky%2Fcloud.cxx;h=7042c568c95b567be4ec8b025c729a429499640f;hb=ab29063a974b1262365112f68a1823d59d99e9b1;hp=c98582a413ee516277a3884cfbf1952692e00209;hpb=f6c9af488b51fa2a5aeb6fecb1206bd22386b728;p=simgear.git

diff --git a/simgear/scene/sky/cloud.cxx b/simgear/scene/sky/cloud.cxx
index c98582a4..7042c568 100644
--- a/simgear/scene/sky/cloud.cxx
+++ b/simgear/scene/sky/cloud.cxx
@@ -42,7 +42,7 @@
 #include "cloud.hxx"
 
 
-static ssgSimpleState *layer_states[SGCloudLayer::SG_MAX_CLOUD_COVERAGES];
+static ssgStateSelector *layer_states[SGCloudLayer::SG_MAX_CLOUD_COVERAGES];
 static bool state_initialized = false;
 
 
@@ -50,6 +50,7 @@ static bool state_initialized = false;
 SGCloudLayer::SGCloudLayer( const string &tex_path ) :
     layer_root(new ssgRoot),
     layer_transform(new ssgTransform),
+    state_sel(0),
     texture_path(tex_path),
     layer_span(0.0),
     layer_asl(0.0),
@@ -162,30 +163,54 @@ SGCloudLayer::rebuild()
         SG_LOG(SG_ASTRO, SG_INFO, "initializing cloud layers");
 
         SGPath cloud_path;
+        ssgStateSelector *state_sel;
+        ssgSimpleState *state;
 
+        state_sel = new ssgStateSelector( 2 );
+        state_sel->ref();
         cloud_path.set(texture_path.str());
         cloud_path.append("overcast.rgb");
-        layer_states[SG_CLOUD_OVERCAST] = sgCloudMakeState(cloud_path.str());
+        state_sel->setStep( 0, sgCloudMakeState(cloud_path.str()) );
+        cloud_path.set(texture_path.str());
+        cloud_path.append("overcast_top.rgb");
+        state_sel->setStep( 1, sgCloudMakeState(cloud_path.str()) );
+        layer_states[SG_CLOUD_OVERCAST] = state_sel;
 
+        state_sel = new ssgStateSelector( 2 );
+        state_sel->ref();
         cloud_path.set(texture_path.str());
         cloud_path.append("broken.rgba");
-        layer_states[SG_CLOUD_BROKEN]
-            = sgCloudMakeState(cloud_path.str());
+        state = sgCloudMakeState(cloud_path.str());
+        state_sel->setStep( 0, state );
+        state_sel->setStep( 1, state );
+        layer_states[SG_CLOUD_BROKEN] = state_sel;
 
+        state_sel = new ssgStateSelector( 2 );
+        state_sel->ref();
         cloud_path.set(texture_path.str());
         cloud_path.append("scattered.rgba");
-        layer_states[SG_CLOUD_SCATTERED]
-            = sgCloudMakeState(cloud_path.str());
+        state = sgCloudMakeState(cloud_path.str());
+        state_sel->setStep( 0, state );
+        state_sel->setStep( 1, state );
+        layer_states[SG_CLOUD_SCATTERED] = state_sel;
 
+        state_sel = new ssgStateSelector( 2 );
+        state_sel->ref();
         cloud_path.set(texture_path.str());
         cloud_path.append("few.rgba");
-        layer_states[SG_CLOUD_FEW]
-            = sgCloudMakeState(cloud_path.str());
+        state = sgCloudMakeState(cloud_path.str());
+        state_sel->setStep( 0, state );
+        state_sel->setStep( 1, state );
+        layer_states[SG_CLOUD_FEW] = state_sel;
 
+        state_sel = new ssgStateSelector( 2 );
+        state_sel->ref();
         cloud_path.set(texture_path.str());
         cloud_path.append("cirrus.rgba");
-        layer_states[SG_CLOUD_CIRRUS]
-            = sgCloudMakeState(cloud_path.str());
+        state = sgCloudMakeState(cloud_path.str());
+        state_sel->setStep( 0, state );
+        state_sel->setStep( 1, state );
+        layer_states[SG_CLOUD_CIRRUS] = state_sel;
 
         layer_states[SG_CLOUD_CLEAR] = 0;
     }
@@ -203,7 +228,16 @@ SGCloudLayer::rebuild()
 
     const float layer_scale = layer_span / scale;
     const float mpi = SG_PI/4;
-    const float alt_diff = layer_asl * 0.8;
+
+    // caclculate the difference between a flat-earth model and 
+    // a round earth model given the span and altutude ASL of
+    // the cloud layer. This is the difference in altitude between
+    // the top of the inverted bowl and the edge of the bowl.
+    // const float alt_diff = layer_asl * 0.8;
+    const float layer_to_core = (SG_EARTH_RAD * 1000 + layer_asl);
+    const float layer_angle = acos( 0.5*layer_span / layer_to_core);
+    const float border_to_core = layer_to_core * sin(layer_angle);
+    const float alt_diff = layer_to_core - border_to_core;
 
     for (int i = 0; i < 4; i++)
     {
@@ -276,6 +310,7 @@ SGCloudLayer::rebuild()
         if ( layer_states[layer_coverage] != NULL ) {
             layer[i]->setState( layer_states[layer_coverage] );
         }
+        state_sel = layer_states[layer_coverage];
     }
 
     // force a repaint of the sky colors with arbitrary defaults
@@ -467,8 +502,9 @@ bool SGCloudLayer::reposition( sgVec3 p, sgVec3 up, double lon, double lat,
 }
 
 
-void SGCloudLayer::draw() {
+void SGCloudLayer::draw( bool top ) {
     if ( layer_coverage != SG_CLOUD_CLEAR ) {
+        state_sel->selectStep( top ? 1 : 0 );
         ssgCullAndDraw( layer_root );
     }
 }
@@ -495,9 +531,5 @@ ssgSimpleState *sgCloudMakeState( const string &path ) {
     state->enable( GL_ALPHA_TEST );
     state->setAlphaClamp( 0.01 );
 
-    // ref() the state so it doesn't get deleted if the last layer of
-    // it's type is deleted.
-    state->ref();
-
     return state;
 }