THREE-DIMENSIONAL GRAPHICS PACKAGES

                                   Design of 3 dimensional packages needs some concerns that don't seem to be necessary with two-dimensional packages. a big distinction between the 2 packages is that a three-dimensional package should embrace strategies for mapping scene descriptions onto a flat viewing surface. we'd like to think about implementation procedures for choosing completely different completely different views and for victimisation different projection techniques. we have a tendency to additionally have to be compelled to contemplate however surfaces of solid objects are to be sculpturesque, however visible surfaces is known, however transformations of objects are performed in area, and the way to explain the extra special properties introduced by 3 dimensions. Later chapters explore every of those concerns intimately. different concerns for three-dimensional packages are undemanding extensions from two-dimensional strategies. World-coordinate descriptions are extended to a few dimensions, and users are given output and input routines accessed with specifications like
                                    polyline3 (n, wcpoints)
                                    fillarea3 (n, wcpoints)
                                    text3 (wcpoint, string)
                                    getLocator3 (wcpoint)
                                    translate3 (translate Vector, matrix Translate)

Where points and vectors are nominal with 3 elements and transformation matrices have four rows and 4 columns. Two-dimensional attribute functions that are freelance of geometric concerns is applied in each two-dimensional and three-dimensional applications. No new attribute functions would like be outlined for colours, line designs, marker attributes, or text fonts. Attribute procedures for orientated character strings, how- ever, have to be compelled to be extended to accommodate discretionary special orientations.

Text-at- tribute routines related to the up vector needs growth to incorporate z-coordinate information in order that strings is given any special orientation. Area-filling routines, like those for positioning the pattern reference and for mapping patterns onto a fill space, have to be compelled to be swollen to accommodate numerous orientations of the fill-area plane and also the pattern plane. Also, most of the two-dimensional structure operations mentioned in earlier chapters is carried over to a three-dimensional package. once object definitions are regenerate to viewing coordinates and projected to the show plane, scan- conversion algorithms are applied to store the formation image.