Adding color to VBO.

A color can be specified to render the geometry of the VBO.
For legacy painting glColor is used, for shader a uniform is set.
In order to allow rendering without texcoords, it is possible to pass
a null pointer as texcoords.
Shader added to scene which just renders a colored geometry without texturing.

lib/kwinglutils.cpp

@@ -1229,6 +1229,8 @@ class GLVertexBufferPrivate
             , numberVertices( 0 )
             , dimension( 2 )
             , useShader( false )
+            , useColor( false )
+            , color( 0, 0, 0, 255 )
             {
             if( GLVertexBufferPrivate::supported )
                 {
@@ -1250,6 +1252,8 @@ class GLVertexBufferPrivate
         static bool supported;
         QVector<float> legacyVertices;
         QVector<float> legacyTexCoords;
+        bool useColor;
+        QColor color;
 
         void legacyPainting( QRegion region, GLenum primitiveMode );
         void corePainting( const QRegion& region, GLenum primitiveMode );
@@ -1262,8 +1266,14 @@ void GLVertexBufferPrivate::legacyPainting( QRegion region, GLenum primitiveMode
     // Enable arrays
     glEnableClientState( GL_VERTEX_ARRAY );
     glVertexPointer( dimension, GL_FLOAT, 0, legacyVertices.constData() );
-    glEnableClientState( GL_TEXTURE_COORD_ARRAY );
-    glTexCoordPointer( 2, GL_FLOAT, 0, legacyTexCoords.constData() );
+    if (!legacyTexCoords.isEmpty()) {
+        glEnableClientState( GL_TEXTURE_COORD_ARRAY );
+        glTexCoordPointer( 2, GL_FLOAT, 0, legacyTexCoords.constData() );
+    }
+
+    if (useColor) {
+        glColor4f(color.redF(), color.greenF(), color.blueF(), color.alphaF());
+    }
 
     // Clip using scissoring
     PaintClipper pc( region );
@@ -1275,7 +1285,9 @@ void GLVertexBufferPrivate::legacyPainting( QRegion region, GLenum primitiveMode
         }
 
     glDisableClientState( GL_VERTEX_ARRAY );
-    glDisableClientState( GL_TEXTURE_COORD_ARRAY );
+    if (!legacyTexCoords.isEmpty()) {
+        glDisableClientState( GL_TEXTURE_COORD_ARRAY );
+    }
 #endif
     }
 
@@ -1296,6 +1308,13 @@ void GLVertexBufferPrivate::corePainting( const QRegion& region, GLenum primitiv
     glBindBuffer( GL_ARRAY_BUFFER, buffers[ 1 ] );
     glVertexAttribPointer( texAttrib, 2, GL_FLOAT, GL_FALSE, 0, 0 );
 
+    if (useColor) {
+        GLint colorLocation = glGetUniformLocation(currentProgram, "geometryColor");
+        if (colorLocation != 0) {
+            glUniform4f(currentProgram, color.redF(), color.greenF(), color.blueF(), color.alphaF());
+        }
+    }
+
     // TODO: reenable paint clipper
     // Clip using scissoring
     PaintClipper pc( region );
@@ -1339,11 +1358,12 @@ void GLVertexBuffer::setData( int numberVertices, int dim, const float* vertices
             d->legacyVertices << vertices[i];
             }
         d->legacyTexCoords.clear();
-        d->legacyTexCoords.reserve( numberVertices * 2 );
-        for( int i=0; i<numberVertices*2; ++i)
-            {
-            d->legacyTexCoords << texcoords[i];
+        if (texcoords != NULL) {
+            d->legacyTexCoords.reserve( numberVertices * 2 );
+            for (int i=0; i<numberVertices*2; ++i) {
+                d->legacyTexCoords << texcoords[i];
             }
+        }
         return;
         }
     GLenum hint;
@@ -1366,8 +1386,10 @@ void GLVertexBuffer::setData( int numberVertices, int dim, const float* vertices
     glBindBuffer( GL_ARRAY_BUFFER, d->buffers[ 0 ] );
     glBufferData( GL_ARRAY_BUFFER, sizeof(GLfloat)*numberVertices*d->dimension, vertices, hint );
 
-    glBindBuffer( GL_ARRAY_BUFFER, d->buffers[ 1 ] );
-    glBufferData( GL_ARRAY_BUFFER, sizeof(GLfloat)*numberVertices*2, texcoords, hint );
+    if (texcoords != NULL) {
+        glBindBuffer( GL_ARRAY_BUFFER, d->buffers[ 1 ] );
+        glBufferData( GL_ARRAY_BUFFER, sizeof(GLfloat)*numberVertices*2, texcoords, hint );
+    }
 
     glBindBuffer( GL_ARRAY_BUFFER, 0 );
     }
@@ -1398,6 +1420,10 @@ void GLVertexBuffer::render( const QRegion& region, GLenum primitiveMode )
     glBindBuffer( GL_ARRAY_BUFFER, d->buffers[ 1 ] );
     glTexCoordPointer( 2, GL_FLOAT, 0, 0 );
 
+    if (d->useColor) {
+        glColor4f(d->color.redF(), d->color.greenF(), d->color.blueF(), d->color.alphaF());
+    }
+
     // Clip using scissoring
     PaintClipper pc( region );
     for( PaintClipper::Iterator iterator;
@@ -1429,6 +1455,22 @@ bool GLVertexBuffer::isSupported()
     return GLVertexBufferPrivate::supported;
     }
 
+bool GLVertexBuffer::isUseColor() const
+{
+    return d->useColor;
+}
+
+void GLVertexBuffer::setUseColor(bool enable)
+{
+    d->useColor = enable;
+}
+
+void GLVertexBuffer::setColor(const QColor& color, bool enable)
+{
+    d->useColor = enable;
+    d->color = color;
+}
+
 void GLVertexBuffer::initStatic()
     {
 #ifdef KWIN_HAVE_OPENGLES

lib/kwinglutils.h

@@ -404,6 +404,33 @@ class KWIN_EXPORT GLVertexBuffer
          * @since 4.7
          **/
         bool isUseShader() const;
+        /**
+         * Sets the color the geometry will be rendered with.
+         * For legacy rendering glColor is used before rendering the geometry.
+         * For core shader a uniform "geometryColor" is expected and is set.
+         * @param color The color to render the geometry
+         * @param enableColor Whether the geometry should be rendered with a color or not
+         * @see setUseColor
+         * @see isUseColor
+         * @since 4.7
+         **/
+        void setColor(const QColor& color, bool enableColor = true);
+        /**
+         * @return @c true if geometry will be painted with a color, @c false otherwise
+         * @see setUseColor
+         * @see setColor
+         * @since 4.7
+         **/
+        bool isUseColor() const;
+        /**
+         * Enables/Disables rendering the geometry with a color.
+         * If no color is set an opaque, black color is used.
+         * @param enable Enable/Disable rendering with color
+         * @see isUseColor
+         * @see setColor
+         * @since 4.7
+         **/
+        void setUseColor(bool enable);
 
         /**
          * @internal

resources.qrc

@@ -4,6 +4,8 @@
   <file>lanczos-fragment.glsl</file>
   <file>scene-vertex.glsl</file>
   <file>scene-fragment.glsl</file>
+  <file>scene-color-vertex.glsl</file>
+  <file>scene-color-fragment.glsl</file>
   <file>scene-generic-vertex.glsl</file>
 </qresource>
 </RCC>

scene-color-fragment.glsl

@@ -0,0 +1,11 @@
+#ifdef GL_ES
+precision highp float;
+#endif
+uniform vec4 geometryColor;
+
+// not used
+varying vec2 varyingTexCoords;
+
+void main() {
+    gl_FragColor = geometryColor;
+}

scene-color-vertex.glsl

@@ -0,0 +1,14 @@
+#ifdef GL_ES
+precision highp float;
+#endif
+// size of the complete display in pixels, x==width, y==height
+uniform vec2 displaySize;
+// geometry of the window/texture to be rendered: x, y, width, height in display geometry
+uniform vec4 geometry;
+
+// passed in vertex - only x and y are used
+attribute vec4 vertex;
+
+void main() {
+    gl_Position.xy = 2.0*vec2(geometry.x + vertex.x, displaySize.y - vertex.y - geometry.y)/displaySize - vertex.ww;
+}

scene_opengl.cpp

@@ -166,6 +166,22 @@ bool SceneOpenGL::setupSceneShaders()
         kDebug(1212) << "Generic Scene Shader is not valid";
         return false;
     }
+    m_colorShader = new GLShader(":/resources/scene-color-vertex.glsl", ":/resources/scene-color-fragment.glsl");
+    if (m_colorShader->isValid()) {
+        m_colorShader->bind();
+        m_colorShader->setUniform("displaySize", QVector2D(displayWidth(), displayHeight()));
+        m_colorShader->unbind();
+        kDebug(1212) << "Color Shader is valid";
+    } else {
+        delete m_genericSceneShader;
+        m_genericSceneShader = NULL;
+        delete m_sceneShader;
+        m_sceneShader = NULL;
+        delete m_colorShader;
+        m_colorShader = NULL;
+        kDebug(1212) << "Color Scene Shader is not valid";
+        return false;
+    }
     return true;
 }
 

scene_opengl.h

@@ -53,7 +53,7 @@ class SceneOpenGL
         virtual void windowDeleted( Deleted* );
         GLShader* sceneShader() const;
         bool hasSceneShader() const {
-            return m_sceneShader != NULL && m_genericSceneShader != NULL;
+            return m_sceneShader != NULL && m_genericSceneShader != NULL && m_colorShader != NULL;
         }
     protected:
         virtual void paintGenericScreen( int mask, ScreenPaintData data );
@@ -109,6 +109,7 @@ class SceneOpenGL
         bool selfCheckDone;
         GLShader* m_sceneShader;
         GLShader* m_genericSceneShader;
+        GLShader* m_colorShader;
         bool debug;
     };
 

scene_opengl_egl.cpp

@@ -33,6 +33,7 @@ SceneOpenGL::SceneOpenGL( Workspace* ws )
     , selfCheckDone( true )
     , m_sceneShader( NULL )
     , m_genericSceneShader( NULL )
+    , m_colorShader( NULL )
     {
     if( !initRenderingContext() )
         return;

scene_opengl_glx.cpp

@@ -41,6 +41,7 @@ SceneOpenGL::SceneOpenGL( Workspace* ws )
     , selfCheckDone( false )
     , m_sceneShader( NULL )
     , m_genericSceneShader( NULL )
+    , m_colorShader( NULL )
     {
     if( !Extensions::glxAvailable())
         {