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GeneralRe: double to CString and back Pin
Zac Howland19-Jul-06 4:32
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GeneralRe: double to CString and back Pin
toxcct19-Jul-06 4:46
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GeneralRe: double to CString and back [modified] Pin
Zac Howland19-Jul-06 4:55
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GeneralRe: double to CString and back Pin
toxcct19-Jul-06 5:00
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QuestionGDI+ and Zooming on the picture ... Pin
Hadi Rezaee19-Jul-06 0:22
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QuestionFinding if the target platform supports 64 bit Arithmetic Pin
ComplexLifeForm19-Jul-06 0:19
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AnswerRe: Finding if the target platform supports 64 bit Arithmetic Pin
Steve S19-Jul-06 1:39
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AnswerRe: Finding if the target platform supports 64 bit Arithmetic Pin
Chris Losinger19-Jul-06 1:41
professionalChris Losinger19-Jul-06 1:41 
Questionvs c++ Pin
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AnswerRe: vs c++ Pin
toxcct18-Jul-06 23:56
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GeneralRe: vs c++ Pin
see me19-Jul-06 0:07
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GeneralRe: vs c++ Pin
toxcct19-Jul-06 0:11
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GeneralRe: vs c++ Pin
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GeneralRe: vs c++ Pin
toxcct19-Jul-06 0:24
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GeneralRe: vs c++ Pin
see me19-Jul-06 0:34
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GeneralRe: vs c++ Pin
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AnswerRe: vs c++ Pin
sunit519-Jul-06 0:01
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AnswerRe: vs c++ Pin
_AnsHUMAN_ 19-Jul-06 0:21
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GeneralRe: vs c++ Pin
see me19-Jul-06 0:31
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AnswerRe: vs c++ Pin
Ștefan-Mihai MOGA19-Jul-06 0:35
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Questionpush n pop matrix Pin
ooola rocks18-Jul-06 23:22
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AnswerRe: push n pop matrix Pin
toxcct18-Jul-06 23:54
toxcct18-Jul-06 23:54 
GeneralRe: push n pop matrix Pin
Steve S19-Jul-06 1:39
Steve S19-Jul-06 1:39 
AnswerRe: push n pop matrix Pin
Maximilien19-Jul-06 3:01
Maximilien19-Jul-06 3:01 
AnswerRe: push n pop matrix [modified] Pin
Rilhas21-Jul-06 12:44
Rilhas21-Jul-06 12:44 
I think you already gt a technical answer. A conceptual one could be:

One reason to push or pop matrices is to "accumulate" matrixes, or, in other words, make "hierarchical" transformations.

For example, if you are animating a robot arm, you may move the finger (relative to the point where it is attached to the wrist).

Then you push the matrix (to save it and "remember" its state) and move the wrist relative to the radio (and the finger should be transformed as well, since the wrist is attached to the radio, and the finger to the wrist).

Then you push the matrix again and move the radio relative to the elbow (and the finger and wrist should be transformed as well). And so on.

In the end you pop all the matrices and get the expected result (combined result).

The result is that these movements allow hierarchical relashionships. If it is programmed correctly, then when you rotate the shoulder joint then all the attached components (humerus, radio, wrist, and finger) will move as if they were all connected (as intended).

The advantage is that you don't have to compute all the individual movements relative to the world, because with push and pop they may be relative to each other. If the "parent" moves then all "childs" move.

Anyway, the programming of these tasks will appear reversed in OpenGL, so take this information as a simple and not so accurate conceptual explanation. Once you grasped the concept and its usefullness you should study the technical aspects and play a little with it (by making objects with hierarchical components, and see the efects of accumulating transformations).

I hope this helps,
Rilhas



-- modified at 18:45 Friday 21st July, 2006

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