| 摘要 |
A method and apparatus are provided for compressing vertex parameter data in a 3D computer graphic system, where the vertex parameter data is a data block relating to a plurality of vertices used for rendering an image. The data relating to each vertex includes multiple byte data relating to at least one parameter. The parameters include X, Y and Z coordinates and further coordinates for texturing and shading. The multiple byte data is divided into individual bytes and bytes with corresponding byte positions relating to each vertex are grouped together to form a plurality of byte blocks. In one embodiment at least one of the byte blocks is compressed by storing at least one byte in a byte block as a byte origin and storing each of the remaining bytes in the byte block as a difference value from one of the byte origins. In the second embodiment at least one the byte blocks is compressed by identifying the unique bytes in the byte block, storing at least one of the unique bytes as a raw byte origin in a byte delta table, storing in the byte delta table remaining unique bytes as difference values from the preceding byte or from the byte origin, and forming a byte index encoding the bytes in the byte block by reference to the byte delta table. Decompression means are also provided for decompressing vertex parameter data thus compressed. These are able to access randomly the compressed data, rather than having to read a stream of data. |
