Thorsten Renk:

Add a 4th layer to the sun (next to disc, inner halo and outer halo). While the inner/outer halos change with atmosphere conditions, the new layer is supposed to represent the effect of blinding brilliance - ideally it adds a suitable ray structure to the sun. The effect is most prominent in space (where I'm most keen on seeing it admittedly) because there all atmospheric halo effects are absent and we end with a really unrealistic white disc.

Some screenshots and discussion there

http://forum.flightgear.org/viewtopic.php?f=47&t=27216

diff --git a/simgear/scene/sky/oursun.cxx b/simgear/scene/sky/oursun.cxx
index f4b049ee99f91b8657a9d89983b54d5b52a28b07..be78ca6c7309a7b8cade13f8836c0a256014e3d3 100644 (file)
--- a/simgear/scene/sky/oursun.cxx
+++ b/simgear/scene/sky/oursun.cxx
@@ -216,6 +216,46 @@ SGSun::build( SGPath path, double sun_size, SGPropertyNode *property_tree_Node )
 
     sun_transform->addChild( geode );
 
+
+    // set up the brilliance state
+
+    geode = new osg::Geode;
+    stateSet = geode->getOrCreateStateSet();
+    stateSet->setRenderBinDetails(-9, "RenderBin");
+
+
+    texture = SGLoadTexture2D("brilliance.png", options.get());
+    stateSet->setTextureAttributeAndModes(0, texture);
+
+
+    // Build ssg structure
+    brilliance_cl = new osg::Vec4Array;
+    brilliance_cl->push_back(osg::Vec4(1, 1, 1, 1));
+
+    double brilliance_size = sun_size * 12.0;
+    osg::Vec3Array* brilliance_vl = new osg::Vec3Array;
+    brilliance_vl->push_back(osg::Vec3(-brilliance_size, 0, -brilliance_size));
+    brilliance_vl->push_back(osg::Vec3(brilliance_size, 0, -brilliance_size));
+    brilliance_vl->push_back(osg::Vec3(-brilliance_size, 0, brilliance_size));
+    brilliance_vl->push_back(osg::Vec3(brilliance_size, 0, brilliance_size));
+
+    osg::Vec2Array* brilliance_tl = new osg::Vec2Array;
+    brilliance_tl->push_back(osg::Vec2(0, 0));
+    brilliance_tl->push_back(osg::Vec2(1, 0));
+    brilliance_tl->push_back(osg::Vec2(0, 1));
+    brilliance_tl->push_back(osg::Vec2(1, 1));
+
+    geometry = new osg::Geometry;
+    geometry->setUseDisplayList(false);
+    geometry->setVertexArray(brilliance_vl);
+    geometry->setColorArray(brilliance_cl.get(), osg::Array::BIND_OVERALL);
+    geometry->setNormalBinding(osg::Geometry::BIND_OFF);
+    geometry->setTexCoordArray(0, brilliance_tl, osg::Array::BIND_PER_VERTEX);
+    geometry->addPrimitiveSet(new osg::DrawArrays(GL_TRIANGLE_STRIP, 0, 4));
+    geode->addDrawable(geometry);
+
+    sun_transform->addChild( geode );
+
     // force a repaint of the sun colors with arbitrary defaults
     repaint( 0.0, 1.0 );
 
@@ -262,7 +302,7 @@ bool SGSun::repaint( double sun_angle, double new_visibility ) {
         }
 
         // ok, now let's go and generate the sun and scene color
-        osg::Vec4 i_halo_color, o_halo_color, scene_color, sun_color;
+        osg::Vec4 i_halo_color, o_halo_color, scene_color, sun_color, brilliance_color;
 
         // Some comments:
         // * When the sunangle changes, light has to travel a longer
@@ -336,16 +376,29 @@ bool SGSun::repaint( double sun_angle, double new_visibility ) {
         if (o_halo_color[3] > 1) o_halo_color[3] = 1;
         if (o_halo_color[3] < 0) o_halo_color[3] = 0;
 
+       brilliance_color[0] = i_halo_color[0];
+       brilliance_color[1] = i_halo_color[1];
+       brilliance_color[2] = i_halo_color[2];
+
+       double norm = (i_halo_color[0] * i_halo_color[0] + i_halo_color[1] * i_halo_color[1] + i_halo_color[2] * i_halo_color[2])/1.732;
+
+       brilliance_color[3] = pow(norm, 6.0);
+       if (brilliance_color[3] < 0.0) {brilliance_color[3] = 0.0;}
+       
+
+
         gamma_correct_rgb( i_halo_color._v );
         gamma_correct_rgb( o_halo_color._v );
         gamma_correct_rgb( scene_color._v );
         gamma_correct_rgb( sun_color._v );
+        gamma_correct_rgb( brilliance_color._v );
 
        if (sun_angle >91.0 * 3.1415/180.0 + horizon_angle)
                {
                sun_color[3] = 0;
                o_halo_color[3]=0;
                i_halo_color[3]=0;
+               brilliance_color[3]=0;
                }
 
         (*sun_cl)[0] = sun_color;
@@ -356,6 +409,8 @@ bool SGSun::repaint( double sun_angle, double new_visibility ) {
         ihalo_cl->dirty();
         (*ohalo_cl)[0] = o_halo_color;
         ohalo_cl->dirty();
+       (*brilliance_cl)[0] = brilliance_color;
+        brilliance_cl->dirty();
     }
 
     return true;

diff --git a/simgear/scene/sky/oursun.hxx b/simgear/scene/sky/oursun.hxx
index bd1f3db10895653985ecfb2f8eb8c572617c5f35..e1e2b75ce854822b2d6453cb9705118caf650c2f 100644 (file)
--- a/simgear/scene/sky/oursun.hxx
+++ b/simgear/scene/sky/oursun.hxx
@@ -45,6 +45,7 @@ class SGSun : public SGReferenced {
     osg::ref_ptr<osg::Vec4Array> scene_cl;
     osg::ref_ptr<osg::Vec4Array> ihalo_cl;
     osg::ref_ptr<osg::Vec4Array> ohalo_cl;
+    osg::ref_ptr<osg::Vec4Array> brilliance_cl;
 
     double visibility;
     double prev_sun_angle;