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Facing another player/object, Redux

by Novack · in Torque Game Engine · 05/25/2009 (9:28 pm) · 9 replies

Hi, inhabitants of the double G hills! Im in need of a hand here.

Found this resource to face an object by rotating the player around the Z axis, commonly known as Yaw.

It works like a charm for Yaw, but I need to adjust the Pitch as well, that is, to rotate the Player/Camera around the X Axis. Hence, my initial mod over the resource, denoted by ***1***, surprisingly not working (surprisingly for me, thats it ;).

After some extensive reading, I tried a second approach, by using MatrixCreateFromEuler() (denoted in the code below as ***2***) which neither work, and in fact produced the same effect as with approach 1: The Pitch rotation not only doesnt work, but also affects the Yaw (!?)

So I have at this point two doubts:
  • The math part, on how Im getting the Pitch angle (*** Critical Point A ***)
  • The whole thing of setting the Pitch not working for some alien reason
function Player::lookAtTarget(%this, %target)
{
   // This is not the problem, but commented out for simplicity
   // %target.eyePos = getWords(%target.getEyeTransform(), 0, 2);
   // %this.eyePos = getWords(%this.getEyeTransform(), 0, 2);   
   // %forward = VectorSub(%target.eyePos, %this.eyePos);

   %forward = VectorSub(%target.getPosition(), %this.getPosition()); 
   
   %x = getWord(%forward, 0);
   %y = getWord(%forward, 1);
   %z = getWord(%forward, 2);
   
   %angleYaw = -mAtan(-%x, %y);
   %anglePitch = -mAtan(%z, mSqrt(%x*%x + %y*%y)); // *** Critical Point A ***
                                                   // Im asuming this is correct,
                                                   // for getting the Pitch angle, 
                                                   // salvaged it from other resource
   
   %tYaw = %this.getPosition();
   %tYaw = %tYaw SPC "0 0 1" SPC %angleYaw;
   %this.setTransform(%tYaw);

   // ***1***
   //%tPitch = %this.getPosition();
   //%tPitch = %tPitch SPC "1 0 0" SPC %anglePitch;
   //%this.setTransform(%tPitch);

   // ***2***   
   //%tmpM = MatrixCreateFromEuler(%anglePitch SPC "0" SPC %angleYaw); 
   //%tFinal = getWords(%this.getPosition(), 0, 2) SPC GetWords(%tmpM, 3, 6);     
   //%client = %this.getControllingClient();
   //%client.camera.setTransform(%tFinal); 
}

Thanks in advance for any math genious (or not), that can visualize my mistake.
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Torque 3D Owner Nicolai Dutka
#1
05/25/2009 (9:46 pm)
Good luck on Pitch... as far as 'ControlObject' is concerned, from what I have read, it is impossible to do through script alone...

Torque 3D Owner Novack
CyberianSoftware
#2
05/25/2009 (9:54 pm)
Mhh. Do you remember where did you read that? If I can confirm the hint, I would start working C++ side... What a hassle.

Torque 3D Owner Nicolas Buquet
#3
05/25/2009 (11:56 pm)
It seems to remember that the player class is build to always have its Z up.

If that's really the case, you can't rotate the player around its X axis.

For the camera, it is possible with the advanced camera resource (I tested it). Don't know with stock TGE camera code.

Nicolas Buquet
www.buquet-net.com/cv/

Associate Michael Hall
Distracted...
#4
05/26/2009 (12:29 am)
I never tried using this for players, but you may derive some use out of it, if only to tell you what rotation you need.
function pointToPos(%posOne, %posTwo)
{
    // sub the two positions so we get a vector pointing from the origin in the
    // direction we want our object to face
    %vec = VectorSub(%posTwo, %posOne);
	
    // pull the values out of the vector
    %x = firstWord(%vec);
    %y = getWord(%vec, 1);
    %z = getWord(%vec, 2);
	
    // this finds the distance from origin to our point
    %len = vectorLen(%vec);
	
    // -------- X
    // given the rise and length of our vector this will give us the angle in radians
    %rotAngleX = mATan(%z, %len);
	
    // -------- Z
    // get the angle for the z axis
    %rotAngleZ = mATan(%x, %y);
	
    // create 2 matrices, one for the z rotation, the other for the x rotation
    %matrix = MatrixCreateFromEuler("0 0" SPC %rotAngleZ * -1);
    %matrix2 = MatrixCreateFromEuler(%rotAngleX SPC "0 0");
	
    // now multiply them together so we end up with the rotation we want
    %finalMat = MatrixMultiply(%matrix, %matrix2);
	
    // we're done, send the proper numbers back
    return getWords(%finalMat, 3, 6);
}

Torque 3D Owner Novack
CyberianSoftware
#5
05/26/2009 (5:09 am)
Thanks for the info Nicholas. I dont completely follow what you say though, what you mean by always have its Z up?

@Michael, Interesting, much appreciated, I will test that today.


Associate Orion Elenzil
Real Life Plus
#6
05/26/2009 (6:37 am)
there's a few places in the C code which make the assumption (and enforce it) that player objects are always vertical. ie, that the player's local Z axis is parallel to the world's Z axis.

eg, try setting the transform of your player to 90-degrees around X:
%playerObj.setTransform("0 0 0 1 0 0" SPC mDegToRad(90))
you'll notice that nothing happens.

i think overcoming this is a fair bit of work.
you might consider using the flying vehicle as your player class instead,
although i'm not sure what other strings are attached to that.

Torque 3D Owner Nicolas Buquet
#7
05/26/2009 (9:17 am)
Orion expressed it better than me.

There was a resource about quaternions who seems to allow player not to be always vertical : www.garagegames.com/community/resources/view/16149

Hope it can help.

Nicolas Buquet
www.buquet-net.com/cv/

Torque 3D Owner Novack
CyberianSoftware
#8
05/26/2009 (3:01 pm)
Again, thank you guys. I will consider carefully what to do.

Torque Owner Javier Canon
#9
11/19/2009 (3:27 am)
how i can make that the player face to a mouse click or mouse position?, i tried some options without lucky... ex. when click on the terrain, you dont have a %targetObject

i have captured the onMouseClick from the playgui and works fine (left and rigth), like a RTS