| 摘要 |
A spotlight characteristic which provides an illumination effect to a polygonal image displayed by an image processor is formed by using a table, and the number of light sources which can be used in an image scene is increased to exceed the number of light sources which can be used simultaneously. To realize this, in a method for forming a spotlight effect characteristic provided to pixels constituting the polygon, a plurality of characteristic values corresponding to a predetermined spotlight characteristic curve are stored in a table, and the spotlight characteristic curve is formed by interpolated values found by interpolating characteristic values read out of the table and adjacent characteristics values. Also, an inner product of an optical axis vector of a spot and a light vector toward a pixel is found, and by using the value of the inner product thus found as an address, the characteristic value is read out of the corresponding address in the table. In addition, the image processor is provided with a buffer for storing data of light sources which are not fewer than light sources which can be used simultaneously, means for appending as many light source identification symbols as the number of light sources affected by each polygon, means for reading the light source information from the buffer in accordance with the light source identification symbols, and means for shading in accordance with the light source information.
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