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Index › Programming Questions & Help › OpenGL and 3D Libraries › reading the modeling/view matrix in Processing
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reading the modeling/view matrix in Processing (Read 763 times)
coordinator69
reading the modeling/view matrix in Processing
Jun 25th, 2006, 6:40am  
First question:  Is it possible to read back the transformation matrix in Processing?  I know that you can printCamera() and printProjection to display it on the screen, but is there a way to get this into an array so that you can use this information within your program?

Second question:  Is there a way to read the z-buffer in Processing?
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st33d
Re: reading the modeling/view matrix in Processing
Reply #1 - Jun 25th, 2006, 12:20pm  
1st:

http://processing.org/reference/printMatrix_.html

http://processing.org/reference/applyMatrix_.html

http://processing.org/reference/resetMatrix_.html
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coordinator69
Re: reading the modeling/view matrix in Processing
Reply #2 - Jun 25th, 2006, 9:22pm  
Thanks for the links, but I need to be able to get the projection and modelview matrix values into arrays or variables so that I can actual do my own computation on them, not just view them on the screen.

As for the second question, I found my answer.  I can use g.zbuffer[y*width+x].  As for properly interpreting the z-buffer values, I need to know the projection matrix.
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st33d
Re: reading the modeling/view matrix in Processing
Reply #3 - Jun 25th, 2006, 11:26pm  
The values of the matrix are stored in a PMatrix instance called modelview that is inside "g", the applet display image.

Since this is digging around in the developers back garden, I warn you that they may start to restructure things on a whim and you may find your code not working in future.

Anyway, now that you've been warned:
Code:

void setup(){
  size(100,100,P3D);
  println(g.modelview.m00);
}

Each of the 16 matrix entries are named m00, m01, m02, etc. See the following source for illumination.

http://dev.processing.org/source/index.cgi/trunk/processing/core/PGraphics3.java?rev=2286&view=markup
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coordinator69
Re: reading the modeling/view matrix in Processing
Reply #4 - Jun 26th, 2006, 5:18am  
Thank you.  That's what I was looking for.
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