| 摘要 |
PURPOSE:To reduce the number of bits for showing transparency by constituting a method so that the part for which color attribute information for showing that there is no action to plotting is imparted does not work on plotting in the case of superposing a pattern subjected to mapping conversion to a plotting area. CONSTITUTION:By a command from a CPU 2, data of a main memory 3 are subjected to three-dimensional coordinate transformation and two-dimensional transformation on a screen by a coordinate transformation device 7, and by the CPU 2, a sorting processing for determining the sequence for plotting a polygon on the screen is executed. An image synthesizing device 6 calculates the gradient of data subjected to sorting, plots a polygon, and outputs its image. In such a state, in a frame memory 10 connected to the image synthesizing device 6, a texture area, a plotting area, and plural color look-up table (CLUT) are provided, and the CLUT can be selected at every texture. Also, a transparent color can be defined to the color information of the texture, and at the time of superposing a texture pattern to the image of a plotting area, the transparent color does not work on the image of the plotting area. |
