# Changes between Version 11 and Version 12 of MousePicking

Show
Ignore:
Timestamp:
05/18/06 16:10:37 (13 years ago)
Comment:

--

Unmodified
Removed
Modified
• ## MousePicking

v11 v12
143143
144144=== Clipping Space to View Space ===
145A point in view space is transformed to clipping space with the {{{GL_PROJECTION}}} matrix:
146
147{{{
148#!latex-math-hook
149\begin{eqnarray*}
150{\boldsymbol P}{\boldsymbol v}&=&{\boldsymbol c} \\
151\text{where} \\
152{\boldsymbol P}&=&\text{projection matrix} \\
153\boldsymbol{v} &=& \text{point in view space} \\
154\boldsymbol{c} &=& \text{point in clip space} \\
155\end{eqnarray*}
156}}}
157
158Given this we can do the opposite by multiplying the clipping space coordinate by the inverse of the {{{GL_PROJECTION}}} matrix.  This isn't as bad as it sounds since we can avoid computing a true 4x4 matrix inverse if we just construct the inverse projection matrix at the same time we build the projection matrix.
159
160A typical OpenGL projection matrix takes the form:
161