wip

shaders/star_new_frag.glsl

@@ -10,8 +10,8 @@ varying highp float brightness;
 /*uniform*/ const float sigma2 = 0.35;
 /*uniform highp*/ const float glareFalloff = 1.0 / 15.0;
 /*uniform highp*/ const float glareBrightness = 0.003;
-/*uniform*/ const float diffSpikeBrightness = 0.3;
+/*uniform*/ const float diffSpikeBrightness = 0.9;
-/*uniform*/ const float exposure = 21.72534925735687;
+uniform /*const*/ float exposure/* = 21.72534925735687|74.430977*/;
 
 mediump vec3 linearToSRGB(mediump vec3 c)
 {
@@ -31,5 +31,5 @@ void main()
     float spikes = (max(0.0, 1.0 - abs(offset.x + offset.y)) + max(0.0, 1.0 - abs(offset.x - offset.y))) * diffSpikeBrightness;
     b += glareBrightness / (glareFalloff * pow(r2, 1.5) + 1.0) * (spikes + 0.5);
 #endif
-    gl_FragColor = vec4(linearToSRGB(b * exposure * color.rgb * brightness), 1.0);
+    gl_FragColor = vec4(linearToSRGB(b * exposure * color.rgb * brightness * 5.0), 1.0);
 }

shaders/star_new_vert.glsl

@@ -11,12 +11,12 @@ attribute vec4 in_Color;
 uniform vec2 viewportSize;
 uniform vec2 viewportCoord;
 
-/*uniform*/ const float magScale = 1.3369011415551906;
+uniform /*const*/ float magScale/* = 1.3369011415551906*/;
 /*uniform*/ const float sigma2 = 0.35;
 /*uniform highp*/ const float glareFalloff = 1.0 / 15.0;
 /*uniform highp*/ const float glareBrightness = 0.003;
-/*uniform*/ const float exposure = 21.72534925735687;
+uniform /*const*/ float exposure /*= 21.72534925735687|74.430977*/;
-/*uniform*/ const float thresholdBrightness = 1.0 / 255.0;
+uniform /*const*/ float thresholdBrightness/* = 1.0 / 255.0*/;
 
 varying vec2 pointCenter;
 varying vec4 color;

src/celengine/pointstarvertexbuffer.cpp

@@ -31,10 +31,11 @@ PointStarVertexBuffer::~PointStarVertexBuffer()
     delete[] vertices;
 }
 
-void PointStarVertexBuffer::startSprites()
+void PointStarVertexBuffer::startSprites(float _limitingMagnitude)
 {
     program = renderer.getShaderManager().getShader("star_new");
     pointSizeFromVertex = true;
+    limitingMagnitude = _limitingMagnitude;
 }
 
 void PointStarVertexBuffer::startBasicPoints()
@@ -82,6 +83,14 @@ void PointStarVertexBuffer::makeCurrent()
     renderer.getViewport(viewport);
     program->vec2Param("viewportSize") = Eigen::Vector2f(viewport[2], viewport[3]);
     program->vec2Param("viewportCoord") = Eigen::Vector2f(viewport[0], viewport[1]);
+    float visibilityThreshold = 1.0f / 255.0f;
+    float logMVisThreshold = log(visibilityThreshold) / log(2.512f);
+    float saturationMag = limitingMagnitude - 4.5f; //+ logMVisThreshold;
+    float magScale = (logMVisThreshold) / (saturationMag - limitingMagnitude);
+    program->floatParam("thresholdBrightness") = visibilityThreshold;
+    program->floatParam("exposure") = pow(2.512f, magScale * saturationMag);
+    program->floatParam("magScale") = magScale;
+
     if (pointSizeFromVertex)
     {
         program->samplerParam("starTex") = 0;

src/celengine/pointstarvertexbuffer.h

@@ -32,7 +32,7 @@ public:
     PointStarVertexBuffer& operator=(PointStarVertexBuffer&&) = delete;
 
     void startBasicPoints();
-    void startSprites();
+    void startSprites(float);
     void render();
     void finish();
     inline void addStar(const Eigen::Vector3f& pos, const Color&, float);
@@ -59,6 +59,7 @@ private:
     Texture* texture            { nullptr };
     bool pointSizeFromVertex    { false };
     float pointScale            { 1.0f };
+    float limitingMagnitude     { 7.0f };
     CelestiaGLProgram* program  { nullptr };
 
     static PointStarVertexBuffer* current;

src/celengine/render.cpp

@@ -4649,11 +4649,11 @@ void Renderer::renderPointStars(const StarDatabase& starDB,
     starRenderer.glareVertexBuffer->setPointScale(screenDpi / 96.0f);
 
     PointStarVertexBuffer::enable();
-    starRenderer.glareVertexBuffer->startSprites();
+    starRenderer.glareVertexBuffer->startSprites(faintestMag);
     if (starStyle == PointStars)
         starRenderer.starVertexBuffer->startBasicPoints();
     else
-        starRenderer.starVertexBuffer->startSprites();
+        starRenderer.starVertexBuffer->startSprites(faintestMag);
 
 #ifdef OCTREE_DEBUG
     m_starProcStats.nodes = 0;