Patent ID: 7362327
Filing Date: 2008-04-22
Classification: G06T

Abstract:
1. An image drawing apparatus that draws an object, which includes multiple polygons and has a changing transparency, in a frame buffer with reference to a Z-buffer, comprising: a change rate setting section that sets a transparency change rate of the object; a threshold setting section that sets a transparency threshold used for determining whether a Z value of a view coordinate system should be written to the Z-buffer according to the set change rate in connection with each pixel where each of the multiple polygons is perspective-transformed from a viewpoint and projected on a virtual screen; a Z value calculating section that calculates the Z value of each pixel projected on the virtual screen in connection with each of the multiple polygons; a transparency calculating section that calculates transparency of each pixel projected on the virtual screen according to the set change rate; a transparency comparing section that compares the calculated transparency of each pixel with the set transparency threshold; a Z-buffer writing section that writes the calculated Z value of the pixel to the Z-buffer when the transparency is lower than the transparency threshold; an image writing section that writes image data of each pixel projected on the virtual screen to the frame buffer with reference to the Z value of each pixel written to the Z-buffer; and a display control section that causes a display to display an image corresponding to image data written to the frame buffer.