System and method for determining illumination of a pixel by shadow planes

A graphics processing circuit, comprising:

• a pixel shader operative to provide pixel position information for at least one pixel of interest in response to image data representing a scene to be rendered;
• a texture circuit, coupled to the pixel shader, operative to determine a luminance value to be applied to the at least one pixel of interest, wherein the luminance value is determined by:
• defining a plane containing the at least one pixel of interest, wherein the plane is defined by a plurality of planar values;
• comparing the plurality of planar values to a corresponding set of shadow map distance values;
• and
• determining a first luminance value for the plane based on the comparison of the plurality of planar values to the corresponding set of shadow map distance values;
• determining a second luminance value for the at least one pixel of interest based on the first luminance value;
• and
• a render back end circuit, coupled to the texture circuit, operative to apply the second luminance value to the pixel of interest.

A non-transitory storage media comprising:

• executable instructions that when executed by one or more processing devices, causes the one or more processing devices to:
• receive position information for at least one pixel of interest to be rendered
• define a plane containing the at least one pixel of interest, the plane being defined by a plurality of planar values;
• compare the plurality of planar values to a corresponding set of shadow map distance values;
• determine a first luminance value for the plane based on the comparison of the plurality of planar values to the corresponding set of shadow map distance values;
• determine a second luminance value for the at least one pixel of interest based on the first luminance value;
• and
• apply the second luminance value to the at least one pixel of interest.