Page 123 - DCAP504_Computer Graphics

Computer Graphics

For the center of a polygon or the polygon’s first vertex, the values may be
calculated. Here, the variations in shade are not produced for this polygon that
should actually occur in this case.

Gouraud Shading

Gouraud shading also known as intensity interpolation shading, does not support intensity
discontinuity. The figure 8.6 is a triangle with all its vertices having different shades. The second figure
displays all the shades that are displayed in vertices and the edges of the shaded triangle.

Figure 8.6 : Gouraud Shading

Source: http://www.dcemu.co.uk/vbulletin/threads/172575-Gouraud-Shading-Test-(Sega-Saturn-Techdemo)
Gouraud shading is based on the concept of another shading method known as interpolation shading.
This method interpolates polygon vertex illumination values that take the approximate values of
polygons. It requires that the normal is known for each vertex of the polygonal mesh.

Interpolation Shading
Here the shading information is interpolated in a linear manner across a triangle from
the values that are determined for its vertices. This method is conveniently used in scan
line algorithms.

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