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Projective texture mapping is a method of texture mapping that allows a textured image to be projected onto a scene as if by a slide projector. Projective texture mapping is useful in a variety of lighting techniques and it is the starting point for shadow mapping. Projective texture mapping is essentially a special matrix transformation which is performed per-vertex and then linearly interpolated as standard texture mapping. == Fixed function pipeline approach == Historically, using projective texture mapping involved considering a special form of eye linear texture coordinate generation transform (''tcGen'' for short). This transform was then multiplied by another matrix representing the projector's properties which was stored in texture coordinate transform matrix. The resulting concatenated matrix was basically a function of both projector properties and vertex eye positions. The key points of this approach are that eye linear tcGen is a function of vertex eye coordinates, which is a result of both eye properties and object space vertex coordinates (more specifically, the object space vertex position is transformed by the model-view-projection matrix). Because of that, the corresponding texture matrix can be used to "shift" the eye properties so the concatenated result is the same as using an eye linear tcGen from a point of view which can be different from the observer. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Projective texture mapping」の詳細全文を読む スポンサード リンク
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