Note that because the origin of the worldcoordinatespace is at the upper-left corner of the client area, the page coordinates are the same as the world coordinates.
请注意，由于全局座标空间的原点位于工作区的左上角，因此画面座标和全局座标是相同的。
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This article lies the initial groundwork required for establishing a ray pick routine, by providing algorithms and working code to convert a pixel coordinate into a ray in worldspace.