Autodesk 62205-051408-9001 User Guide - Page 174

5 Compositing Using OpenGL OpenGL delivers high-performance 2D and 3D graphics. With the correct hardware, you can use OpenGL to improve performance in the viewports. For example, a broadcast design project may have lots of moving text and graphics. If you play the composite clip in an OpenGL viewport, you can preview the result quickly. The workflow is smoother and more interactive since you can see changes as you make them. You can also render using OpenGL. Instead of rendering using the software-based renderer, image files are saved from the output of your OpenGL graphics card. This is useful for quick renders as you work on a project. Note: Some advanced composition attributes such as ambient lighting, spot light falloff and reflections will not produce the same results as they would in software rendering mode. In such cases, software rendering is recommended for final rendering. Keep in mind that some OpenGL graphics accelerator cards include limited texture memory which may result in limited performance when using OpenGL in Combustion. If you have a limited OpenGL graphics card, it is recommended that you set your Combustion Preferences to Software OpenGL. See Setting OpenGL Preferences. For OpenGL requirements for various types of software see the Autodesk Combustion 2008 Installation Guide for Microsoft Windows. Previewing with OpenGL Any viewport that displays a Composite operator can be switched to OpenGL. The Particles operator automatically switches to an OpenGL view. Other operators cannot take advantage of OpenGL, so this preview option is not available. Note: If you do not have a graphics card that includes OpenGL hardware, the software simulates the OpenGL results. Obviously, this is slower because there is no hardware acceleration. When you switch a viewport to use OpenGL, the graphics in the viewport are generated by your OpenGL hardware. Combustion sends OpenGL instructions to the graphics card, so the softwarebased renderer is not used. The OpenGL preview can display most of the composite features in Combustion. Refer to the following table. Cards All Some None Support These Features Layers and their transformations, transparency, surface properties, lights, shading, shadows, Normal and Add transfer modes. Subtract transfer mode, reflections, Normal and Add reflection modes. All other transfer modes not already listed above, all other reflection modes not listed above, 3D Depth, 3D Shading, stencil layers. Note: Surface properties include luminosity, diffuse level, specular level, and glossiness. You can also set the display quality. For example, you can set the viewports to Best to use anti-aliasing and supersampling. Features that are unsupported are automatically disabled or unavailable in the controls for the Composite operator. (For example, an unsupported transfer mode appears in lighter gray in the list.) This is also true if the required hardware is not present for a feature that is only supported on some cards. In other words, if the required OpenGL extensions are not available for a feature, you cannot display it. If the composite uses such a feature when you show the OpenGL preview, Combustion displays a warning icon in the Info palette located across the bottom of the screen; double-click the warning icon to show a list of the error messages. A sample 158