Add comments and tidying.

examples/common/OpenGLWidget.cpp

@@ -26,27 +26,32 @@ void OpenGLWidget::setShader(QSharedPointer<QGLShaderProgram> shader)
 void OpenGLWidget::setViewableRegion(Region viewableRegion)
 {
 	m_viewableRegion = viewableRegion;
+
+	// The user has specifed a new viewable region
+	// so we need to regenerate our camera matrix.
 	setupWorldToCameraMatrix();
 }
 
 void OpenGLWidget::mousePressEvent(QMouseEvent* event)
 {
+	// Initialise these variables which will be used when the mouse actually moves.
 	m_CurrentMousePos = event->pos();
 	m_LastFrameMousePos = m_CurrentMousePos;
-
-	update();
 }
 
 void OpenGLWidget::mouseMoveEvent(QMouseEvent* event)
 {
+	// Update the x and y rotations based on the mouse movement.
 	m_CurrentMousePos = event->pos();
 	QPoint diff = m_CurrentMousePos - m_LastFrameMousePos;
 	m_xRotation += diff.x();
 	m_yRotation += diff.y();
 	m_LastFrameMousePos = m_CurrentMousePos;
 
+	// The camera rotation has changed so we need to regenerate the matrix.
 	setupWorldToCameraMatrix();
 
+	// Re-render.
 	update();
 }
 

examples/common/OpenGLWidget.h

@@ -52,7 +52,7 @@ public:
 	// Constructor
 	OpenGLWidget(QWidget *parent);
 
-	// Convert a SurfaceMesh to OpenGL index/vertex buffers. Inlined because it's templatised.
+	// Convert a PolyVox mesh to OpenGL index/vertex buffers. Inlined because it's templatised.
 	template <typename MeshType>
 	void addMesh(const MeshType& surfaceMesh, const PolyVox::Vector3DInt32& translation = PolyVox::Vector3DInt32(0, 0, 0), float scale = 1.0f)
 	{
@@ -78,24 +78,32 @@ public:
 		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, meshData.indexBuffer);
 		glBufferData(GL_ELEMENT_ARRAY_BUFFER, vecIndices.size() * sizeof(uint32_t), vecIndices.data(), GL_STATIC_DRAW);
 
-		//We need to tell OpenGL how to understand the format of the vertex data
+		// Every surface extractor outputs valid positions for the vertices, so tell OpenGL how these are laid out
-		glEnableVertexAttribArray(0); //We're talking about shader attribute '0' 
+		glEnableVertexAttribArray(0); // Attrib '0' is the vertex positions
 		glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(MeshType::VertexType), (GLvoid*)(offsetof(MeshType::VertexType, position))); //take the first 3 floats from every sizeof(decltype(vecVertices)::value_type)
 
-		glEnableVertexAttribArray(1); //We're talking about shader attribute '1'
+		// Some surface extractors also generate normals, so tell OpenGL how these are laid out. If a surface extractor
+		// does not generate normals then nonsense values are written into the buffer here and sghould be ignored by the
+		// shader. This is mostly just to simplify this example code - in a real application you will know whether your
+		// chosen surface extractor generates normals and can skip uploading them if not.
+		glEnableVertexAttribArray(1); // Attrib '1' is the vertex normals.
 		glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(MeshType::VertexType), (GLvoid*)(offsetof(MeshType::VertexType, normal)));
 
+		// Finally a surface extractor will probably output additional data. This is highly application dependant. For this example code 
+		// we're just uploading it as a set of bytes which we can read individually, but real code will want to do something specialised here.
 		glEnableVertexAttribArray(2); //We're talking about shader attribute '2'
-		GLint size = (std::min)(sizeof(MeshType::VertexType::VoxelType), size_t(4));
+		GLint size = (std::min)(sizeof(MeshType::VertexType::VoxelType), size_t(4)); // Can't upload more that 4 components (vec4 is GLSL's biggest type)
 		glVertexAttribIPointer(2, size, GL_UNSIGNED_BYTE, sizeof(MeshType::VertexType), (GLvoid*)(offsetof(MeshType::VertexType, material)));
 
+		// We're done uploading and can now unbind.
 		glBindVertexArray(0);
 
-		meshData.noOfIndices = vecIndices.size(); //Save this for the call to glDrawElements later
+		// A few additional properties can be copied across for use during rendering.
-
+		meshData.noOfIndices = vecIndices.size();
 		meshData.translation = QVector3D(translation.getX(), translation.getY(), translation.getZ());
 		meshData.scale = scale;
 
+		// Now add the mesh to the list of meshes to render.
 		mMeshData.push_back(meshData);
 	}