camera system object centric

Graphics and GPU Programming Programming

Started by giugio August 01, 2011 12:40 PM

2 comments, last by kauna 12 years, 8 months ago

giugio

246

Author

August 01, 2011 12:40 PM

hello.
I have this function in webgl for a camera system:



function handleMouseMove(event) {



        	if (!mouseDown) {

            	return;

        	}

        	var newX = event.clientX;

        	var newY = event.clientY;



        	var deltaX = newX - lastMouseX

        	var newRotationMatrix = mat4.create();

        	mat4.identity(newRotationMatrix);

        	mat4.rotate(newRotationMatrix, degToRad(deltaX / 10), [0, 1, 0]);



        	var deltaY = newY - lastMouseY;

        	mat4.rotate(newRotationMatrix, degToRad(deltaY / 10), [1, 0, 0]);





        	mat4.multiply(newRotationMatrix, RotationMatrix, RotationMatrix);



        	lastMouseX = newX

        	lastMouseY = newY;

    	}

the problem is that this camera system is not object centered.
I wish, when rotate , rotates the object around its axis and for the traslation go ahead and back.
I already done for traslation and mouse weel, but i don't know how do for the rotation of the camera around object.
How i can find the object axis? i have a bounding sphere, and his center.
thanks.

kauna

2,925

August 01, 2011 01:36 PM

You could use the object's world transformation to find out the axis you'll wish to rotate around.

You should find a function called LookAt to generate a view matrix from desired location to the center of your object. Now, only thing you'll need to do is to rotate the camera location around the axis you get from the world matrix.

Possibly, there might even be a function for that.

Cheers!

giugio

246

Author

August 01, 2011 02:17 PM

You could use the object's world transformation to find out the axis you'll wish to rotate around.

You should find a function called LookAt to generate a view matrix from desired location to the center of your object. Now, only thing you'll need to do is to rotate the camera location around the axis you get from the world matrix.

Possibly, there might even be a function for that.

Cheers!

thanks, but how i can find the object axis?

kauna

2,925

August 02, 2011 07:13 AM

[quote name='kauna' timestamp='1312205794' post='4843112']
You could use the object's world transformation to find out the axis you'll wish to rotate around.

You should find a function called LookAt to generate a view matrix from desired location to the center of your object. Now, only thing you'll need to do is to rotate the camera location around the axis you get from the world matrix.

Possibly, there might even be a function for that.

Cheers!

thanks, but how i can find the object axis?
[/quote]

Well, you should look in to the world transform matrix of the object, which practically contains 3 vectors describing the XYZ-axises of rotation.

Does it matter that you camera rotates around the object's axis or do you just want your camera to rotate around the object regardless of the object axis?

Cheers!

camera system object centric

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