Add the ability to feather borders of screenspace renderables

include/openspace/rendering/screenspacerenderable.h

@@ -140,6 +140,7 @@ protected:
     // Border
     properties::FloatProperty _borderWidth;
     properties::Vec3Property _borderColor;
+    properties::BoolProperty _borderFeather;
 
     properties::FloatProperty _scale;
     properties::FloatProperty _gammaOffset;
@@ -149,7 +150,7 @@ protected:
 
     glm::ivec2 _objectSize = glm::ivec2(0);
     UniformCache(color, opacity, blackoutFactor, hue, value, saturation, mvpMatrix, tex,
-        backgroundColor, gamma, borderColor, borderWidth) _uniformCache;
+        backgroundColor, gamma, borderColor, borderWidth, borderFeather) _uniformCache;
     std::unique_ptr<ghoul::opengl::ProgramObject> _shader;
 };
 

modules/base/shaders/screenspace_fs.glsl

@@ -40,6 +40,7 @@ uniform float saturation;
 uniform float gamma = 1.0;
 uniform vec2 borderWidth = vec2(0.1);
 uniform vec3 borderColor = vec3(0.0);
+uniform int borderFeather = 0;
 
 
 Fragment getFragment() {
@@ -54,6 +55,13 @@ Fragment getFragment() {
       vs_st.y < borderWidth.y || vs_st.y > 1 - borderWidth.y)
   {
     frag.color = vec4(borderColor, opacity);
+    if (borderFeather == 1) {
+      vec2 f1 = vs_st / borderWidth;
+      float g1 = min(f1.x, f1.y);
+      vec2 f2 = (vec2(1) - vs_st) / borderWidth;
+      float g2 = min(f2.x, f2.y);
+      frag.color *= min(g1, g2);
+    }
   }
 
   if (frag.color.a == 0.0) {

src/rendering/screenspacerenderable.cpp

@@ -169,6 +169,13 @@ namespace {
         openspace::properties::Property::Visibility::NoviceUser
     };
 
+    constexpr openspace::properties::Property::PropertyInfo BorderFeatherInfo = {
+        "BorderFeather",
+        "Border Feather",
+        "If this value is enabled and a border width is set, the border will be rendered "
+        "as a feathered border rather than a hard corner."
+    };
+
     float wrap(float value, float min, float max) {
         return glm::mod(value - min, max - min) + min;
     }
@@ -222,6 +229,9 @@ namespace {
         // [[codegen::verbatim(BorderColorInfo.description)]]
         std::optional<glm::vec3> borderColor [[codegen::color()]];
 
+        // [[codegen::verbatim(BorderFeatherInfo.description)]]
+        std::optional<bool> borderFeather;
+
         // [[codegen::verbatim(ScaleInfo.description)]]
         std::optional<float> scale;
 
@@ -318,6 +328,7 @@ ScreenSpaceRenderable::ScreenSpaceRenderable(const ghoul::Dictionary& dictionary
     )
     , _borderWidth(BorderWidthInfo, 0.f, 0.f, 1000.f)
     , _borderColor(BorderColorInfo, glm::vec3(0.f), glm::vec3(0.f), glm::vec3(1.f))
+    , _borderFeather(BorderFeatherInfo, false)
     , _scale(ScaleInfo, 0.25f, 0.f, 2.f)
     , _gammaOffset(GammaOffsetInfo, 0.f, -1.f, 10.f)
     , _multiplyColor(MultiplyColorInfo, glm::vec3(1.f), glm::vec3(0.f), glm::vec3(1.f))
@@ -368,6 +379,7 @@ ScreenSpaceRenderable::ScreenSpaceRenderable(const ghoul::Dictionary& dictionary
 
     addProperty(_borderColor);
     addProperty(_borderWidth);
+    addProperty(_borderFeather);
 
     _borderWidth = p.borderWidth.value_or(_borderWidth);
 
@@ -667,6 +679,7 @@ void ScreenSpaceRenderable::draw(const glm::mat4& modelTransform,
     _shader->setUniform(_uniformCache.backgroundColor, _backgroundColor);
     _shader->setUniform(_uniformCache.borderWidth, borderUV);
     _shader->setUniform(_uniformCache.borderColor, _borderColor);
+    _shader->setUniform(_uniformCache.borderFeather, _borderFeather);
     _shader->setUniform(
         _uniformCache.mvpMatrix,
         global::renderEngine->scene()->camera()->viewProjectionMatrix() * modelTransform