next »

[elijah]

Is there a way to determine the size of the Quad Shape3D that must be created based upon the Texture Size without stretching the image? The other question is also for button and label size.

[Marvin Fröhlich]

In parallel projection, it's easy. But I guess, that's not, what you want .

If you want to use perspective projection, you could try to do it by casting a pick ray at (w/2,h/2), where w and h are the size if the texture. Then you calculate, w' and h' at the shape's distance from the camera.

Marvin

[elijah]

Is there any code examples in xith-tk ( or books ) that I should look at to help me understand your explanation. It looks very simple. Is it something like

PickRay pr = new PickRay( RenderPassConfig, canvas, canvas.getWidth()/2, canvas.getHeight()/2 ) ;
pr.recalculate( Image.getWidth()/2, Image.getHeight()/2 );

then how to get w' and h' ? Hope you can help me further.

[Marvin Fröhlich]

The recalculate is unnecessary, if you pass the image's size into the constructor.

The rest should be simple vector math.

Code:

// Define a point on the image shape's boundary (where it is located). We start with the pick ray's origin...
Point3f boundary = new Point3f( pr.getOrigin() );
// Set the pick ray's length to the distance from canvas to the image shape.
pr.getDirection().normalize();
pr.getDirection().setLength( absDistanceCanvasToImage );
// ...and add the pick ray's direction vector.
boundary.add( pr.getDirection() );
// Define the center of the image shape (where it is located).
Point3f center = new Point3f( 0f, 0f, -absDistanceCanvasToImage );
// The distance from 'center' to 'boundary' is half of the image shape's height (where it is located).
float height = center.distanceTo( boundary ) * 2f;

The width can now be calculated by using the image's aspect ratio and the calculated height.

The code is untested and written straight from my head. But it should basically work.

Marvin

[elijah]

Thank you for your help. I will try this and will post back on the testing