Limb darkening for stars

Author: 375gnu

src/celengine/render.cpp

@@ -1828,6 +1828,9 @@ static void renderSphereUnlit(const RenderInfo& ri,
         textures.push_back(ri.overlayTex);
     }
 
+    if (ri.isStar)
+        shadprop.lightModel = LightingModel::StarModel;
+
     // Get a shader for the current rendering configuration
     auto* prog = r->getShaderManager().getShader(shadprop);
     if (prog == nullptr)
@@ -1838,6 +1841,8 @@ static void renderSphereUnlit(const RenderInfo& ri,
     prog->textureOffset = 0.0f;
     prog->ambientColor = ri.color.toVector3();
     prog->opacity = 1.0f;
+    if (ri.isStar)
+        prog->eyePosition = ri.eyePos_obj;
 
     Renderer::PipelineState ps;
     ps.depthMask = true;
@@ -2388,6 +2393,7 @@ void Renderer::renderObject(const Vector3f& pos,
         }
         else
         {
+            ri.isStar = obj.isStar;
             renderSphereUnlit(ri, viewFrustum, planetMVP, this);
         }
     }
@@ -3014,6 +3020,7 @@ void Renderer::renderStar(const Star& star,
         surface.appearanceFlags |= Surface::ApplyBaseTexture;
         surface.appearanceFlags |= Surface::Emissive;
 
+        rp.isStar = true;
         rp.surface = &surface;
         rp.rings = nullptr;
         rp.radius = star.getRadius();

src/celengine/render.h

@@ -472,12 +472,15 @@ class Renderer
         Surface* surface{ nullptr };
         const Atmosphere* atmosphere{ nullptr };
         RingSystem* rings{ nullptr };
+        LightingState::EclipseShadowVector* eclipseShadows{ nullptr };
+
+        Eigen::Quaternionf orientation{ Eigen::Quaternionf::Identity() };
+        Eigen::Vector3f semiAxes{ Eigen::Vector3f::Ones() };
         float radius{ 1.0f };
         float geometryScale{ 1.0f };
-        Eigen::Vector3f semiAxes{ Eigen::Vector3f::Ones() };
+
         ResourceHandle geometry{ InvalidResource };
-        Eigen::Quaternionf orientation{ Eigen::Quaternionf::Identity() };
-        LightingState::EclipseShadowVector* eclipseShadows;
+        bool isStar{ false };
     };
 
     struct DepthBufferPartition

src/celengine/renderinfo.h

@@ -21,12 +21,14 @@ class Texture;
 
 struct RenderInfo
 {
-    Color color{ 1.0f, 1.0f, 1.0f };
+    Eigen::Quaternionf orientation{ Eigen::Quaternionf::Identity() };
+
     Texture* baseTex{ nullptr };
     Texture* bumpTex{ nullptr };
     Texture* nightTex{ nullptr };
     Texture* glossTex{ nullptr };
     Texture* overlayTex{ nullptr };
+    Color color{ 1.0f, 1.0f, 1.0f };
     Color specularColor{ 0.0f, 0.0f, 0.0f };
     float specularPower{ 0.0f };
     Eigen::Vector3f sunDir_eye{ Eigen::Vector3f::UnitZ() };
@@ -36,10 +38,9 @@ struct RenderInfo
     Color sunColor{ 1.0f, 1.0f, 1.0f };
     Color ambientColor{ 0.0f, 0.0f, 0.0f };
     float lunarLambert{ 0.0f };
-    Eigen::Quaternionf orientation{ Eigen::Quaternionf::Identity() };
     float pixWidth{ 1.0f };
     float pointScale{ 1.0f };
+    bool isStar{ false };
 };
 
 extern LODSphereMesh* g_lodSphere;
-

src/celengine/shadermanager.cpp

@@ -2093,6 +2093,11 @@ ShaderManager::buildFragmentShader(const ShaderProperties& props)
         source += "gl_FragColor.rgb = gl_FragColor.rgb * scatterEx + scatterColor;\n";
     }
 
+    if (props.lightModel == LightingModel::StarModel)
+    {
+        source += "gl_FragColor.rgb = gl_FragColor.rgb - vec3(1.0 - NV) * vec3(0.56, 0.61, 0.72);\n";
+    }
+
     source += "}\n";
 
     DumpFSSource(source);

src/celengine/shadermanager.h

@@ -62,6 +62,7 @@ enum class LightingModel : std::uint16_t
     EmissiveModel         = 0x0100,
     ParticleModel         = 0x0200,
     UnlitModel            = 0x0400,
+    StarModel             = 0x0800,
 };
 
 ENUM_CLASS_BITWISE_OPS(LightingModel);