| 摘要 |
A video/graphics controller (IMC) which includes a novel spanning based method for rendering and display of 3D graphical data on a display device. The IMC first operates to construct a 3-D Virtual display refresh list (3D-VDRL) in memory. The IMC constructs the 3-D VDRL by first parsing the geometry data, generating independent vertex-sorted geometric primitives (eg, triangles) and then performing setup on the geometric primitives. Setup includes assembling a list of parameters for each of the triangle vertices and determining slope values for the triangle edges. The IMC uses 3D vertex and slope information to compute horizontal segments that make up each triangle. The IMC then performs a Y sort of the triangles for each span line, and an X sort of triangles segments and vertices for each span line. For each span line, triangle segments are generated and X sorted based on starting X position of triangles for each segment. Span lines are horizontal line of pixels that run the entire length of the display device, and segments are portions of the span line that represent horizontal triangle start to stop segments. After the Y and X sorts, the IMC performs a Z rules determination for each span line to discard or reject those segments that are hidden, i.e., to reject the now one-dimensional triangle segments that are hidden by other triangle segments. After the Y and X sorts, and the Z rules determination, which determines the segments that are visible, the IMC then constructs the 3-D VDRL list for each span line comprising pointers which reference viewed triangle spans. During execution of the 3-D VDRL, the 3-D VDRL is read and interpreted for triangle parameter data, texture address, attributes and other control information to generate pixel data. The pixel data includes the viewed triangle spans and may include texture data or other data referenced by the VDRL.
|
