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POOpenGL Rotations around World Origin when they should be around Local Origin
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copied!<p>I'm implementing a simple camera system in OpenGL. I set up gluPerspective under the projection matrix and then use gluLookAt on the ModelView matrix. After this I have my main render loop which checks for keyboard events and, if any of the arrow keys are pressed, modifies angular and forward speeds (I only rotate through the y axis and move through the z (forwards)). Then I move the view using the following code (deltaTime is the amount of time since the last frame was rendered in seconds, in order to decouple movement from framerate):</p> <pre><code>//place our camera newTime = RunTime(); //get the time since app start deltaTime = newTime - time; //get the time since the last frame was rendered time = newTime; glRotatef(view.angularSpeed*deltaTime,0,1,0); //rotate glTranslatef(0,0,view.forwardSpeed*deltaTime); //move forwards //draw our vertices draw(); //swap buffers Swap_Buffers(); </code></pre> <p>Then the code loops around again. My draw algorithm begins with a <code>glPushMatrix()</code> and ends in a <code>glPopMatrix()</code>.</p> <p>Each call to glRotatef() and glTranslatef() pushes the view forwards by the forwards speed in the direction of view.</p> <p>However when I run the code, my object is drawn in the correct place, but when I move the movement is done with the orientation of the world origin (0,0,0 - facing along the Z axis) as opposed to the local orientation (where I'm pointing) and when I rotate, the rotation is done about (0,0,0) and not the position of the camera.</p> <p>I end up with this strange effect of my camera orbiting (0,0,0) as opposed to rotating on the spot.</p> <p>I do not call <code>glLoadIdentity()</code> at all anywhere inside the loop, and I am sure that the Matrix Mode is set to <code>GL_MODELVIEW</code> for the entire loop.</p> <p>Another odd effect is if I put a <code>glLoadIdentity()</code> call inside the <code>draw(</code>) function (between the PushMatrix and PopMatrix calls, the screen just goes black and no matter where I look I can't find the object I draw.</p> <p>Does anybody know what I've messed up in order to make this orbit (0,0,0) instead of rotate on the spot?</p>

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