The two values shown for each coordinate are the current smallest and largest for that coordinate. Initially they are 0.0 and 1.0 for both S and T. The following mapping is used in the tutorial: the texel at coordinates (smallest S, smallest T) is mapped to the lower-left corner of the rectangle, the texel at (largest S, smallest T) is mapped to the lower-right corner, the texel at (largest S, largest T) is mapped to the upper-right corner and the texel at (smallest S, largest T) is mapped to the upper-left corner. If S and T have their initial values, then one instance of the image map is applied to the entire rectangle. If we select the S and T coordinates such that their smallest and largest values are strictly between 0.0 and 1.0, then we are selecting a rectangle of texels that is inside the entire image map.
Let us consider another possible selection and, in particular the following conditons.
smallest S < 0.0, largest S > 1.0 smallest T < 0.0 largest T > 1.0If the Repeat wrapping option is selected for both coordinates and if at least one of the above conditions hold, then the effect is multiple, including partial, instances of the image map appearing on the rectangle. If either of the other wrapping options is selected, then only one instance of the image map is displayed but with a border. The border is filled with the border color for the option Clamp to Border while it is filled with the texels on the corresponding edges of the image map for the option Clamp to Edge.
The window also provides for selecting the four components of the border color (red, green, blue and alpha).
As for any of our tutorials having a parameter input window, we can use either the mouse or the up and down arrow keys to change any of the selectable values that are initially drawn in green.