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How to draw at exact positions instead of relative

Started by Colby_ Feb 22, 2012 at 12:19 AM 2 replies 950+ views

Original Post

Feb 22, 2012 at 12:19 AM

Imagine I have a list of things I want to draw, and their exact positions in relation to the origin. For drawing the first object, I can simply translate to the coordinates of the object and draw it. However, for any object after that one, the points i enter are relative to the last translation. How can I reset similarly to glLoadIdentity(); but without discarding my camera rotations? Surely I dont have to subtract the coordinates of all models or re translate the camera for each position?

For example, say I have two cubes at (0, 5, 0) and (0, 10, 0). I currently must draw them as so:

translatecam
translate(0, 5, 0);
drawcube
translate(0, 5, 0);
drawcube
updatescreen

and I need to be able to do it like so:

translatecam
setresetpoint

translate(0, 5, 0);
drawcube
reset
translate(0, 10, 0);
drawcube
updatescreen

Waterlimon

148

Waterlimon

Feb 22, 2012 at 12:25 AM

I think there is a function for going backwards in the matrix stack, you should call that a few times.

SiCrane

Mod

473

SiCrane

Feb 22, 2012 at 12:56 AM

I think what you want is glPushMatrix() and glPopMatrix().

slicer4ever

390

slicer4ever

Feb 22, 2012 at 6:40 AM

glPushMatrix/glPopMatrix, per above's answer, essentially:


 glMultMatrix(CameraMatrix);
 glPushMatrix();
 glTranslater(0.0f, 5.0f, 0.0f);
 drawCube();
 glPopMatrix()
 glPushMatrix()
 glTranslate(0.0f, 10.0f, 0.0f);
 drawCube();
 glPopMatrix()

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