Output Devices

All forms of rendered output must be associated with an output device. The device object represents the visual display destination for the renderer.

The renderer's behavior depends on the type of output device that is specified. You can define multiple viewports on a device, allowing different aspects of the scene to be viewed simultaneously. You can also specify any number of devices, allowing multiple destination devices for the same scene.

Retained Mode supports devices that render directly to the screen, to windows, or into application memory.

Applications use the IDirect3DRMDevice3, IDirect3DRMDevice2, and IDirect3DRMDevice interfaces to interact with the output device. For related information, see IDirect3DRMDevice3.

This section describes the options available to display Direct3D images to output devices.

Quality
Color Models
Window Management

Quality

The output device allows the scene and its component parts to be rendered with various degrees of realism. The device rendering quality is the maximum quality at which rendering can take place on the rendering surface of that device. Mesh, progressive mesh, and mesh builder objects can also have a specified rendering quality.

A device's or object's quality has three components: shade mode (flat or Gouraud; Phong is not yet implemented and will default to Gouraud shading), lighting type (on or off), and fill mode (point, wireframe or solid).

You can set the quality of a device with IDirect3DRMDevice3::SetQuality and IDirect3DRMDevice3::SetQuality methods. By default, the device quality is D3DRMRENDER_FLAT (flat shading, lights on, and solid fill).

You can set the quality of a Direct3DRMProgressiveMesh, Direct3DRMMeshBuilder3, or Direct3DRMMeshBuilder3 object with their respective SetQuality methods: IDirect3DRMProgressiveMesh::SetQuality, IDirect3DRMMeshBuilder3::SetQuality, and IDirect3DRMMeshBuilder3::SetQuality. By default, the quality of these objects is D3DRMRENDER_GOURAUD (Gouraud shading, lights on, and solid fill).

Tip: Gourad shading gets better performance on progressive mesh objects that change level of detail, often or quickly.

Direct3D Retained Mode renders an object at the lowest quality setting based on the device and object's current setting for each individual component. For example, if the object's current quality setting is D3DRMRENDER_GOURAUD, and the device is D3DRMRENDER_FLAT then the object will be rendered with flat shading, solid fill, and lights on.

If the object's current quality setting is D3DRMSHADE_GOURAUD|D3DRMLIGHT_OFF|D3DRMFILL_WIREFRAME and the device's quality setting is D3DRMSHADE_FLAT|D3DRMLIGHT_ON|D3DRMFILL_POINT, then the object will be rendered with flat shading, lights off, and point fill mode.

These rules apply to Direct3DRMMeshBuilder3 object s, Direct3DRMMeshBuilder3 objects, and Direct3DRMProgressiveMesh objects. However, Direct3DRMMesh objects do not follow these rules. Mesh objects ignore the device's quality settings and use the group quality setting (which defaults to D3DRMRENDER_GOURAUD).

Color Models

Retained Mode supports two color models: an RGB model and a monochromatic (or ramp) model. To retrieve the color model, an application can use the IDirect3DRMDevice3::GetColorModel method.

The RGB model treats color as a combination of red, green, and blue light, and it supports multiple light sources that can be colored. There is no limit to the number of colors in the scene. You can use this model with 8-, 16-, 24-, and 32-bit displays. If the display depth is less than 24 bits, the limited color resolution can produce banding artifacts. You can avoid these artifacts by using optional dithering.

The monochromatic model also supports multiple light sources, but their color content is ignored. Each source is set to a gray intensity. RGB colors at a vertex are interpreted as brightness levels. Brightness levels between vertices with different brightness are interpolated (in Gouraud shading) across the intervening face. The number of differently colored objects in the scene is limited; after all the system's free palette entries are used up, the system's internal palette manager finds colors that already exist in the palette and that most closely match the intended colors. Like the RGB model, you can use this model with 8-, 16-, 24-, and 32-bit displays. (The monochromatic model supports only 8-bit textures, however.) The advantage of the monochromatic model over the RGB model is better performance.

It is not possible to change the color model of a Direct3D device. Your application should use the IDirect3D::EnumDevices or IDirect3D::FindDevice method to identify a driver that supports the required color model, then specify this driver in one of the device-creation methods.

Palettes are supported for textures, off-screen surfaces, and overlay surfaces, none of which is required to have the same palette as the primary surface. If a device supports a 4-bit indexed palette (16 colors) and you have 8-bit indexed art (256 colors), Retained Mode will render the art as 4-bit by taking the first 16 entries from your palette and remapping to those. Therefore, you should put your 16 preferred colors at the front of the palette if possible.

Window Management

For correct operation, applications must inform Direct3D when the WM_MOVE, WM_PAINT, and WM_ACTIVATE messages are received from the operating system by using the IDirect3DRMWinDevice::HandlePaint and IDirect3DRMWinDevice::HandleActivate methods.

For related information, see IDirect3DRMWinDevice.