The opacity of an image defined by an alpha value per pixel interleaved with the color components (for example, ARGB), an alpha value per pixel stored in a separate alpha surface, or a constant alpha value for the entire surface.
alpha color component
The portion of a 32-bit color that determines its opacity. In this case, the alpha value per pixel is interleaved with the color components (for example, ARGB). Less commonly, this term can also refer to an image with an alpha value per pixel stored in a separate alpha surface.
alpha constant
A level of opacity (alpha value) applied to an entire surface.
alpha edge blend
A particular use of alpha blending (and alpha channel information) to reduce aliasing by blending edges, based on pixel coverage information.
ambient
Description of a light source that illuminates everything in a scene, regardless of the orientation, position, and surface characteristics of the objects in the scene. Because it illuminates a scene with equal strength everywhere, the position and orientation of the frame that an ambient light source is attached to are inconsequential. Multiple ambient light sources are combined within a scene.
anisotropic filtering
A mipmap filtering mode that compensates for anisotropic distortion.
anisotropy
The distortion visible in the image of a 3-D object whose surface is oriented at an angle with respect to the viewing plane. The anisotropy is measured as the elongation (length divided by width) of a screen pixel that is inverse-mapped into texture space.
array object
A group of objects organized into an array. Array objects make it simpler to apply operations to the entire group. The COM interfaces that enable you to work with array objects contain the GetElement and GetSize methods. These methods retrieve a pointer to an element in the array and the size of the array, respectively.
attach
To connect multiple DirectDrawSurface objects into complex structures, such as those needed to support 3-D page flipping with z-buffers. Attachment is not bidirectional, and a surface cannot be attached to itself. Emulated surfaces (in system memory) cannot be attached to nonemulated surfaces. Unless one surface is a texture map, the two attached surfaces must be the same size.
attached
Physically connected to the system. A device may be installed but not currently attached.
attack
The period at the beginning of a force-feedback effect when the magnitude is reaching its basic or sustain level.