Graphics system

Claim 2

A graphics system comprising: an object display data generation means for generating pixel data, which is used to display object polygons defining an object, on a screen of a display unit, and depth data relating to said pixel data, a pixel data selection means for selecting and taking out pixel data with the smallest depth for each pixel position, a means for generating shadow polygons, which define a shadow volume created by one of said object polygons intercepting light from a light source, a parity determination means for each pixel position, for each of said shadow volumes, for determining whether or not there are one or more shadow polygons defining the shadow volume concerned, between a depth position of a viewpoint and a depth position of pixel data selected for the pixel position concerned, and for determining a parity of the number of shadow polygons existing between said positions, a viewpoint position evaluation means for determining whether or not said viewpoint exists in the shadow volume relating to the parity determination, a shadow determination means for determining, based on the resultant determination of said parity determination means and said viewpoint position evaluation means, that there is a shadow on said pixel position if said viewpoint is in the shadow volume relating to said parity determination, and said parity determination is even, or if said viewpoint is outside the shadow volume relating to said parity determination, and said parity determination is odd, a pixel data modulation means for modulating the pixel data outputted from said pixel data selection means, based on the resultant determination of said shadow determination means, to reflect the shadow on said pixel data; and, a pixel data outputting means for outputting the modulated pixel data to said display unit.

Claim 3

A graphics system comprising: an object display data generation means for generating pixel data, which is used to display object polygons defining an object, on a screen of a display unit, and depth data relating to said pixel data, a pixel data selection means for selecting and taking out pixel data with the smallest depth for each pixel position, a means for generating shadow polygons, which define a shadow volume created by one of said object polygons intercepting light from a light source, a parity determination means for each pixel position, for each of said shadow volumes, for determining whether or not there are one or more shadow polygons defining the shadow volume concerned, between a depth position of a viewpoint and a depth position of pixel data selected for the pixel position concerned, and for determining a parity of the number of shadow polygons existing between said positions, a viewpoint position evaluation means for determining whether or not said viewpoint exists in the shadow volume relating to the parity determination, a shadow determination means for determining, based on the resultant determination of said parity determination means and said viewpoint position evaluation means, that there is a shadow on said pixel position if said viewpoint is in the shadow volume relating to said parity determination, and said parity determination is even, or if said viewpoint is outside the shadow volume relating to said parity determination, and said parity determination is odd, a counting means for each of said pixel positions, responsive to the resultant determination by said shadow determination means for each of a plurality of light sources, for counting how many of said light sources generate shadows on the pixel position concerned, a pixel data modulation means for modulating the pixel data outputted from said pixel data selection means based on the resultant count of said counting means to reflect the shadows, including penumbrae, on said pixel data; and, a pixel data outputting means for outputting the modulated pixel data to said display unit.

Claim 4

A graphics system comprising: an object display data generation means for generating pixel data, which is used to display object polygons defining an object, on a screen of a display unit, and depth data relating to said pixel data, a pixel data selection means for selecting and taking out pixel data with the smallest depth for each pixel position, a means for generating shadow polygons, which define a shadow volume created by one of said object polygons intercepting light from a light source, a parity determination means for each pixel position, for each of said shadow volumes, for determining whether or not there are one or more shadow polygons defining the shadow volume concerned, between a depth position of a viewpoint and a depth position of pixel data selected for the pixel position concerned, and for determining a parity of the number of shadow polygons existing between said positions, a viewpoint position evaluation means for determining whether or not said viewpoint exists in the shadow volume relating to the parity determination, a shadow determination means for determining, based on the resultant determination of said parity determination means and said viewpoint position evaluation means, that there is a shadow on said pixel position if said viewpoint is in the shadow volume relating to said parity determination, and said parity determination is even, or if said viewpoint is outside the shadow volume relating to said parity determination, and said parity determination is odd, a counting means for each of said pixel positions, responsive to the resultant determination by said shadow determination means for each of a plurality of light sources, for counting how many of said light sources generate shadows on the pixel position concerned, a pixel data modulation means for modulating the pixel data outputted from said pixel data selection means based on the resultant count of said counting means to reflect the shadows, including penumbrae, on said pixel data; and, a pixel data outputting means for outputting the modulated pixel data to said display unit.

Claim 5

A graphics system comprising: an object display data generation means for generating pixel data, which is used to display object polygons defining an object, on a screen of a display unit, and depth data relating to said pixel data, a pixel data selection means for selecting and taking out pixel data with the smallest depth for each pixel position, a means for generating shadow polygons, which define a shadow volume created by one of said object polygons intercepting light from a light source, a parity determination means for each pixel position, for each of said shadow volumes, for determining whether or not there are one or more shadow polygons defining the shadow volume concerned, between a depth position of a viewpoint and a depth position of pixel data selected for the pixel position concerned, and for determining a parity of the number of shadow polygons existing between said positions, a viewpoint position evaluation means for determining whether or not said viewpoint exists in the shadow volume relating to the parity determination, a shadow determination means for determining, based on the resultant determination of said parity determination means and said viewpoint position evaluation means, that there is a shadow on said pixel position if said viewpoint is in the shadow volume relating to said parity determination, and said parity determination is even, or if said viewpoint is outside the shadow volume relating to said parity determination, and said parity determination is odd, a shadow light source data generation means for each of said pixel positions, responsive to the resultant determination by said shadow determination means for each of a plurality of light sources, for generating shadow light source data indicative of which of said light sources generates a shadow on the pixel position concerned, a means for generating for each of said pixel position normal data of an object polygon to which the pixel data occupying said pixel position belongs, a shadow intensity determination means for determining intensity of a shadow based on said shadow light source data and said normal data, a pixel data modulation means for modulating the pixel data from said pixel data selection means based on the shadow intensity data from said shadow intensity determining means to reflect the shadows, including penumbrae, on said pixel data; and a pixel data outputting means for outputting the modulated pixel data to said display unit.

Claim 6

A graphics system comprising: an object display data generation means for generating pixel data, which is used to display object polygons defining an object, on a screen of a display unit, and depth data relating to said pixel data, a pixel data selection means for selecting and taking out pixel data with the smallest depth for each pixel position, a means for generating shadow polygons, which define a shadow volume created by one of said object polygons intercepting light from a light source, a parity determination means for each pixel position, for each of said shadow volumes, for determining whether or not there are one or more shadow polygons defining the shadow volume concerned, between a depth position of a viewpoint and a depth position of pixel data selected for the pixel position concerned, and for determining a parity of the number of shadow polygons existing between said positions, a viewpoint position evaluation means for determining whether or not said viewpoint exists in the shadow volume relating to the parity determination, a shadow determination means for determining, based on the resultant determination of said parity determination means and said viewpoint position evaluation means, that there is a shadow on said pixel position if said viewpoint is in the shadow volume relating to said parity determination, and said parity determination is even, or if said viewpoint is outside the shadow volume relating to said parity determination, and said parity determination is odd, a shadow light source data generation means for each of said pixel positions, responsive to the resultant determination by said shadow determination means for each of a plurality of light sources, for generating shadow light source data indicative of which of said light sources generates a shadow on the pixel position concerned, a means for generating for each of said pixel position normal data of an object polygon to which the pixel data occupying said pixel position belongs, a shadow intensity determination means for determining intensity of a shadow based on said shadow light source data and said normal data, a pixel data modulation means for modulating the pixel data from said pixel data selection means based on the shadow intensity data from said shadow intensity determining means to reflect the shadows, including penumbrae, on said pixel data; and a pixel data outputting means for outputting the modulated pixel data to said display unit.

Claim 7

A graphics system as claimed in Claim 3, wherein said normal data is quantized.

Claim 8

A graphics system as claimed in Claim 4, wherein said object display data generation means, said pixel data selection means, and said parity determination means are composed of a pipeline type processing means.

Claim 9

A graphics system as claimed in any one of Claims 1 to 5 further comprising a processing range limiting means for generating processing range limiting data indicating in which range of a scan line the processing is necessary for said shadow volume; and a processing avoiding means for avoiding unnecessary processing based on said processing range limiting data.