create ShellRenderInterfaceOpenGL::SetViewport, instead of hardcoding

the height of the screen for scissoring. anything that would overflow
y with scrollbars would result in being cut off by a the difference between
768 and the viewports current resolution. even the debugger was broken.

change all examples to use this now as well.

Samples/basic/customlog/src/main.cpp

@@ -61,6 +61,8 @@ int main(int ROCKET_UNUSED(argc), char** ROCKET_UNUSED(argv))
 	// Rocket initialisation.
 	ShellRenderInterfaceOpenGL opengl_renderer;
 	Rocket::Core::SetRenderInterface(&opengl_renderer);
+    opengl_renderer.SetViewport(1024,768);
+
 
 	// Initialise our system interface to write the log messages to file.
 	SystemInterface system_interface;

Samples/basic/drag/src/main.cpp

@@ -61,6 +61,7 @@ int main(int ROCKET_UNUSED(argc), char** ROCKET_UNUSED(argv))
 	// Rocket initialisation.
 	ShellRenderInterfaceOpenGL opengl_renderer;
 	Rocket::Core::SetRenderInterface(&opengl_renderer);
+    opengl_renderer.SetViewport(1024,768);
 
 	ShellSystemInterface system_interface;
 	Rocket::Core::SetSystemInterface(&system_interface);

Samples/basic/loaddocument/src/main.cpp

@@ -60,6 +60,7 @@ int main(int ROCKET_UNUSED(argc), char** ROCKET_UNUSED(argv))
 	// Rocket initialisation.
 	ShellRenderInterfaceOpenGL opengl_renderer;
 	Rocket::Core::SetRenderInterface(&opengl_renderer);
+    opengl_renderer.SetViewport(1024,768);
 
 	ShellSystemInterface system_interface;
 	Rocket::Core::SetSystemInterface(&system_interface);

Samples/basic/treeview/src/main.cpp

@@ -62,6 +62,8 @@ int main(int ROCKET_UNUSED(argc), char** ROCKET_UNUSED(argv))
 
 	// Rocket initialisation.
 	ShellRenderInterfaceOpenGL opengl_renderer;
+    opengl_renderer.SetViewport(1024,768);
+
 	Rocket::Core::SetRenderInterface(&opengl_renderer);
 
 	ShellSystemInterface system_interface;

Samples/invaders/src/main.cpp

@@ -71,6 +71,8 @@ int main(int, char**)
 	// Rocket initialisation.
 	ShellRenderInterfaceOpenGL opengl_renderer;
 	Rocket::Core::SetRenderInterface(&opengl_renderer);
+    opengl_renderer.SetViewport(1024,768);
+
 	ShellSystemInterface system_interface;
 	Rocket::Core::SetSystemInterface(&system_interface);
 

Samples/shell/include/ShellRenderInterfaceOpenGL.h

@@ -41,6 +41,12 @@ class ShellRenderInterfaceOpenGL : public Rocket::Core::RenderInterface
 public:
 	ShellRenderInterfaceOpenGL();
 
+    /**
+     * @p width width of viewport
+     * @p height height of viewport
+     */
+    void SetViewport(int width, int height);
+
 	/// Called by Rocket when it wants to render geometry that it does not wish to optimise.
 	virtual void RenderGeometry(Rocket::Core::Vertex* vertices, int num_vertices, int* indices, int num_indices, Rocket::Core::TextureHandle texture, const Rocket::Core::Vector2f& translation);
 

Samples/shell/src/ShellRenderInterfaceOpenGL.cpp

@@ -34,6 +34,13 @@ ShellRenderInterfaceOpenGL::ShellRenderInterfaceOpenGL()
 {
 }
 
+void ShellRenderInterfaceOpenGL::SetViewport(int width, int height)
+{
+    m_width = width;
+    m_height = height;
+}
+
+
 // Called by Rocket when it wants to render geometry that it does not wish to optimise.
 void ShellRenderInterfaceOpenGL::RenderGeometry(Rocket::Core::Vertex* vertices, int ROCKET_UNUSED(num_vertices), int* indices, int num_indices, const Rocket::Core::TextureHandle texture, const Rocket::Core::Vector2f& translation)
 {
@@ -90,7 +97,7 @@ void ShellRenderInterfaceOpenGL::EnableScissorRegion(bool enable)
 // Called by Rocket when it wants to change the scissor region.		
 void ShellRenderInterfaceOpenGL::SetScissorRegion(int x, int y, int width, int height)
 {
-	glScissor(x, 768 - (y + height), width, height);
+	glScissor(x, m_height - (y + height), width, height);
 }
 
 // Set to byte packing, or the compiler will expand our struct, which means it won't read correctly from file

Samples/tutorial/datagrid/src/main.cpp

@@ -47,6 +47,7 @@ int main(int ROCKET_UNUSED(argc), char** ROCKET_UNUSED(argv))
 	// Rocket initialisation.
 	ShellRenderInterfaceOpenGL opengl_renderer;
 	Rocket::Core::SetRenderInterface(&opengl_renderer);
+    opengl_renderer.SetViewport(1024,768);
 
 	ShellSystemInterface system_interface;
 	Rocket::Core::SetSystemInterface(&system_interface);

Samples/tutorial/datagrid_tree/src/main.cpp

@@ -48,6 +48,7 @@ int main(int ROCKET_UNUSED(argc), char** ROCKET_UNUSED(argv))
 	// Rocket initialisation.
 	ShellRenderInterfaceOpenGL opengl_renderer;
 	Rocket::Core::SetRenderInterface(&opengl_renderer);
+    opengl_renderer.SetViewport(1024, 768);
 
 	ShellSystemInterface system_interface;
 	Rocket::Core::SetSystemInterface(&system_interface);

Samples/tutorial/template/src/main.cpp

@@ -44,6 +44,7 @@ int main(int ROCKET_UNUSED(argc), char** ROCKET_UNUSED(argv))
 	// Rocket initialisation.
 	ShellRenderInterfaceOpenGL opengl_renderer;
 	Rocket::Core::SetRenderInterface(&opengl_renderer);
+    opengl_renderer.SetViewport(1024, 768);
 
 	ShellSystemInterface system_interface;
 	Rocket::Core::SetSystemInterface(&system_interface);

Samples/tutorial/tutorial_drag/src/main.cpp

@@ -45,6 +45,7 @@ int main(int ROCKET_UNUSED(argc), char** ROCKET_UNUSED(argv))
 	// Rocket initialisation.
 	ShellRenderInterfaceOpenGL opengl_renderer;
 	Rocket::Core::SetRenderInterface(&opengl_renderer);
+    opengl_renderer.SetViewport(1024, 768);
 
 	ShellSystemInterface system_interface;
 	Rocket::Core::SetSystemInterface(&system_interface);