From 00a8383214c6dfd0992d7a44b269a0cba8b4ac61 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Sun, 3 Nov 2013 00:18:54 +0100
Subject: [PATCH] Shaders: ability to specify background color in Vector
 shader.

Makes it possible to use the shader without blending.
---
 src/Shaders/Vector.cpp  |  3 ++-
 src/Shaders/Vector.frag |  6 ++++--
 src/Shaders/Vector.h    | 15 +++++++++++++++
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/src/Shaders/Vector.cpp b/src/Shaders/Vector.cpp
index e89db7f86..301ef4770 100644
--- a/src/Shaders/Vector.cpp
+++ b/src/Shaders/Vector.cpp
@@ -38,7 +38,7 @@ namespace {
     template<> constexpr const char* vertexShaderName<3>() { return "AbstractVector3D.vert"; }
 }
 
-template<UnsignedInt dimensions> Vector<dimensions>::Vector(): transformationProjectionMatrixUniform(0), colorUniform(1) {
+template<UnsignedInt dimensions> Vector<dimensions>::Vector(): transformationProjectionMatrixUniform(0), backgroundColorUniform(1), colorUniform(2) {
     Utility::Resource rs("MagnumShaders");
 
     #ifndef MAGNUM_TARGET_GLES
@@ -76,6 +76,7 @@ template<UnsignedInt dimensions> Vector<dimensions>::Vector(): transformationPro
     #endif
     {
         transformationProjectionMatrixUniform = AbstractShaderProgram::uniformLocation("transformationProjectionMatrix");
+        backgroundColorUniform = AbstractShaderProgram::uniformLocation("backgroundColor");
         colorUniform = AbstractShaderProgram::uniformLocation("color");
     }
 
diff --git a/src/Shaders/Vector.frag b/src/Shaders/Vector.frag
index 8dd88fd4c..aa61ad4c4 100644
--- a/src/Shaders/Vector.frag
+++ b/src/Shaders/Vector.frag
@@ -29,8 +29,10 @@
 #endif
 
 #ifdef EXPLICIT_UNIFORM_LOCATION
-layout(location = 1) uniform vec4 color;
+layout(location = 1) uniform vec4 backgroundColor;
+layout(location = 2) uniform vec4 color;
 #else
+uniform lowp vec4 backgroundColor;
 uniform lowp vec4 color;
 #endif
 
@@ -48,5 +50,5 @@ out lowp vec4 fragmentColor;
 
 void main() {
     lowp float intensity = texture(vectorTexture, fragmentTextureCoordinates).r;
-    fragmentColor = intensity*color;
+    fragmentColor = mix(backgroundColor, color, intensity);
 }
diff --git a/src/Shaders/Vector.h b/src/Shaders/Vector.h
index 92e3b3860..10808325d 100644
--- a/src/Shaders/Vector.h
+++ b/src/Shaders/Vector.h
@@ -56,9 +56,23 @@ template<UnsignedInt dimensions> class MAGNUM_SHADERS_EXPORT Vector: public Abst
             return *this;
         }
 
+        /**
+         * @brief Set background color
+         * @return Reference to self (for method chaining)
+         *
+         * Default is transparent black.
+         * @see @ref setColor()
+         */
+        Vector& setBackgroundColor(const Color4& color) {
+            AbstractShaderProgram::setUniform(backgroundColorUniform, color);
+            return *this;
+        }
+
         /**
          * @brief Set fill color
          * @return Reference to self (for method chaining)
+         *
+         * @see @ref setBackgroundColor()
          */
         Vector& setColor(const Color4& color) {
             AbstractShaderProgram::setUniform(colorUniform, color);
@@ -67,6 +81,7 @@ template<UnsignedInt dimensions> class MAGNUM_SHADERS_EXPORT Vector: public Abst
 
     private:
         Int transformationProjectionMatrixUniform,
+            backgroundColorUniform,
             colorUniform;
 };