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glReadPixels(0, 0, w, h, GL_DEPTH_COMPONENT, GL_FLOAT, myDepths);

    QMatrix4x4 matrix;
    matrix.setToIdentity();
    matrix.perspective(fov, ((float)width()/(float)height()), 0.00001, 1000.0);
    matrix.lookAt(e,t,u);

    glLoadMatrixf(matrix.constData());

		// sets depth for spline path occlusion
		// see http://www.fractalforums.com/index.php?topic=16405.0
		gl_FragDepth = ((1000.0 / (1000.0 - 0.00001)) +
		(1000.0 * 0.00001 / (0.00001 - 1000.0)) /
		clamp(Ray.Pos, 0.00001, 1000.0));

quantized space.... eventually:
resolution3d= step size between points in quantized space; 

 if resolution3d= .05;  then  (.13, .06, -.04) =  (.15, .05, -.05)

vec4 pointData <x> [y][z][iteration] =  vec3 orbitTrapData [iteration], distance estimation[iteration];

  Actually will probably bind the point data to textures for storage between redraws, as non-uniforms are lost on redraw.  

	while (fi<=feedbackstop) {   
			if (feedbackcontrol1[fi].x==m) {   //do we apply this iteration???
				zappaz=length (pos-feedback[fi].xyz);  
				if (zappaz<feedbackcontrol2[fi].x) {    // check to see if it is within feedback radius

// if it's in the effect's radius, we do a simple drop off in intensity from the center of the effect (maximum effect) 
// to the edge (0 effect) :     zappaz = (FeedbackRadius-zappaz) * FeedbackStrength;
					zappaz= (feedbackcontrol2[fi].x-zappaz)*feedbackcontrol2[fi].y;
					
					if (feedbackcontrol1[fi].y==1.) {     //FBFormulaType = 1
						if (feedbackcontrol1[fi].z==1.) {   // FBApplicationType = 1
							z2=vec3(zappaz,0.,0.);  // we just add in a vector of zappaz length
//                                                   ////  z2 rotated around FBRotVector by FBRotAngle (we started out on x axis, so..)
							z2*=rotationMatrix3(normalize(feedbackrotation[fi].xyz),feedbackrotation[fi].w);
							z+=z2;   // setting direction with our rotation vectors and angle
						} else if (feedbackcontrol1[fi].z==2.) {   // FBApplicationType = 2
							z2=vec3(zappaz,zappaz,zappaz)*sr13;  // we just add in a vector of zappaz length
//                                                   ////  z2 rotated around FBRotVector by FBRotAngle (we started out on x axis, so..)
							z2*=rotationMatrix3(normalize(feedbackrotation[fi].xyz),feedbackrotation[fi].w);
							z+=z2;   // setting direction with our rotation vectors and angle
						} else if (feedbackcontrol1[fi].z==3.) {
							z+=feedback[fi].xyz*zappaz;
						} else if (feedbackcontrol1[fi].z==4.) {
							zappaz=length(feedback[fi].xyz)*zappaz;
							z2=vec3(zappaz,0.,0.);
							z2*=rotationMatrix3(normalize(feedbackrotation[fi].xyz),feedbackrotation[fi].w);
							z+=z2;
						}
					} else if (feedbackcontrol1[fi].y==2.) {   //formula =2 
						z2= (pos-feedback[fi].xyz)*zappaz;
						z2*=rotationMatrix3(normalize(feedbackrotation[fi].xyz),feedbackrotation[fi].w);
					
						if (feedbackcontrol1[fi].z==1.) {   //app type = 1
							z=z2;
						} else if (feedbackcontrol1[fi].z==2.) {   //app type =2
							z+=z2;
						}
						
					} else if (feedbackcontrol1[fi].y==3.) {  /form 3
						if (feedbackcontrol1[fi].z==1.) {  //app 1
							z*= rotationMatrix3(normalize(feedbackrotation[fi].xyz),feedbackrotation[fi].w*zappaz);
						} else if (feedbackcontrol1[fi].z==2.) {
							if (zappaz<0) {zappaz=-(feedbackrotation[fi].w-zappaz);} else {zappaz+=feedbackrotation[fi].w;}
							z*= rotationMatrix3(normalize(feedbackrotation[fi].xyz),zappaz);
						} else if (feedbackcontrol1[fi].z==3.) {
							if (zappaz<0) {zappaz=zappaz-.1;} else {zappaz=zappaz+.1;}
							z*= rotationMatrix3(normalize(feedbackrotation[fi].xyz),feedbackrotation[fi].w/zappaz);
						} 
						
					}	 else if (feedbackcontrol1[fi].y==4.) {   
					
//heightmap function here
// feedcontrol1.w = texture speed
// feedcontrol2.zw=  heightmap texture offset
// feedbackcontrol1.z= texture to use instead of application type.  

						MapType=HeightMapType;
						textoff=vec2(feedbackcontrol2[fi].z,feedbackcontrol2[fi].w)*.1;
						texturespeed=feedbackcontrol1[fi].w;
						hintensity=zappaz;
						ColorTex=int(feedbackcontrol1[fi].z);    
							z2= z*rotationMatrix3(normalize(feedbackrotation[fi].xyz),feedbackrotation[fi].w);
							z2=TextureIT(vec4(z2,length(z2)));

							z+=z2*hintensity;
					
					}	 else if (feedbackcontrol1[fi].y==5.) {

// this is a fun one, use the FBRotVector for the one part, FeedbackStrength effects this part:
						r=zappaz * length (vec3(
							z.x*feedbackrotation[fi].x,
							z.y*feedbackrotation[fi].y,
							z.z*feedbackrotation[fi].z
							));

//  use the Feedback Variables (1, 2, and 3)  for this part.  You can stretch stuff, or whatever... fun!  

						z=vec3(z.x+feedbackcontrol1[fi].w*r,
								z.y+feedbackcontrol2[fi].z*r,
								z.z+feedbackcontrol2[fi].w*r);
							
					}
				}  //zapparadius check
			}   //feedbackcontrol iteration check
			fi++;
		} // end of while (fi<FeedBacks)

//feedbackcontrol1.x[]     
uniform float ApplyOnIteration;slider[0,0,30]
//feedbackcontrol1.y[]
uniform float FormulaType;slider[1,1,30]
//feedbackcontrol1.z[]
uniform float ApplicationType;slider[1,1,30]

//feedbackcontrol1.x[]     
uniform int ApplyOnIteration;slider[0,0,30]
//feedbackcontrol1.y[]
uniform int FormulaType;slider[1,1,30]
//feedbackcontrol1.z[]
uniform int ApplicationType;slider[1,1,30]

	while (fi<=feedbackstop) {
			if (feedbackcontrol1[fi].x==m) {   //feedbackcontrol1[fi].x =  ApplyOnIteration
				zappaz=length (pos-feedback[fi].xyz);
				if (zappaz<feedbackcontrol2[fi].x) {     //feedbackcontrol2[fi].x= Radius of effect!
							zappaz= (feedbackcontrol2[fi].x-zappaz)*feedbackcontrol2[fi].y;
					       //feedbackcontrol2[fi].y = strength of effect, holding in alt key makes negative!!!
					if (feedbackcontrol1[fi].y==1.) {  //feedcontrol1[fi].y= formula type 
						if (feedbackcontrol1[fi].z==1.) {  //  application type   
							//zappaz=length(feedback[fi].xyz)*zappaz;
							z2=vec3(zappaz,0.,0.);
							z2*=rotationMatrix3(normalize(feedbackrotation[fi].xyz),feedbackrotation[fi].w);
							z+=z2;
						} else if (feedbackcontrol1[fi].z==2.) {
							z+=feedback[fi].xyz*zappaz;
						} else if (feedbackcontrol1[fi].z==3.) {
							zappaz=length(feedback[fi].xyz)*zappaz;
							z2=vec3(zappaz,0.,0.);
							z2*=rotationMatrix3(normalize(feedbackrotation[fi].xyz),feedbackrotation[fi].w);
							z+=z2;
						}
					} else if (feedbackcontrol1[fi].y==2.) {
						z2= (pos-feedback[fi].xyz)*zappaz;
						z2*=rotationMatrix3(normalize(feedbackrotation[fi].xyz),feedbackrotation[fi].w);
					
						if (feedbackcontrol1[fi].z==1.) {
							z=z2;
						} else if (feedbackcontrol1[fi].z==2.) {
							z+=z2;
						}
						
					} else if (feedbackcontrol1[fi].y==3.) {
//formula type 3 lets you rotate around the point- not fully set up yet..  should set it up so that space and the fractal can be
// twisted around a certain line/cylinder
						if (feedbackcontrol1[fi].z==1.) {
							z*= rotationMatrix3(normalize(feedbackrotation[fi].xyz),feedbackrotation[fi].w*zappaz);
						} else if (feedbackcontrol1[fi].z==2.) {
							if (zappaz<0) {zappaz=-(feedbackrotation[fi].w-zappaz);} else {zappaz+=feedbackrotation[fi].w;}
							z*= rotationMatrix3(normalize(feedbackrotation[fi].xyz),zappaz);
						} else if (feedbackcontrol1[fi].z==3.) {
							if (zappaz<0) {zappaz=zappaz-.1;} else {zappaz=zappaz+.1;}
							z*= rotationMatrix3(normalize(feedbackrotation[fi].xyz),feedbackrotation[fi].w/zappaz);
						} 
						
					}	 else if (feedbackcontrol1[fi].y==4.) {
					
//heightmap function here   ***************************************************
// feedcontrol1.w = texture speed        ************    Selecting formula type = 4 get you the heightmap
// feedcontrol2.z=  heightmap texture selection
// zappa uses feedcontrol2.y as the heightmap strength variable... 
						MapType=HeightMapType;
						textoff=vec2(feedbackcontrol2[fi].z,feedbackcontrol2[fi].w)*.1;
						texturespeed=feedbackcontrol1[fi].w;
						hintensity=zappaz;
						ColorTex=int(feedbackcontrol1[fi].z);    //set colortex to height map 1 texture	
							z2= z*rotationMatrix3(normalize(feedbackrotation[fi].xyz),feedbackrotation[fi].w);
							z2=TextureIT(vec4(z2,length(z2)));

							z+=z2*hintensity;

//  I didn't set it up so that you could set up multiple shapes to stamp with yet (square stamp, rectangular, etc.)
//  but you can heightmap specific places at specific iterations....  
						
						
						
					}	 else if (feedbackcontrol1[fi].y==5.) {
//  formula type 5 is sort of cool- you can set it up to stretch and distort based on fractal values... play with this one!
						r=zappaz * length (vec3(
							z.x*feedbackrotation[fi].x,
							z.y*feedbackrotation[fi].y,
							z.z*feedbackrotation[fi].z
							));
						z=vec3(z.x+feedbackcontrol1[fi].w*r,
								z.y+feedbackcontrol2[fi].z*r,
								z.z+feedbackcontrol2[fi].w*r);
							
					}
				}  //zapparadius check
			}   //feedbackcontrol iteration check
			fi++;
		} // end of while (fi<FeedBacks)

Current Zappa:0, -1 : 226,24,0

    /// copy the depth value @ mouse XY
    if(!zapLocked && cameraControl->getID() == "3D")
      glReadPixels ( mouseXY.x(), height() - mouseXY.y(), 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &ZAtMXY );