FlxCamera perspective projection

[flunardelli]

I added a helper function to work with perspective projection in FlxCamera that I think could be useful.

/**
         * Helper function to change the camera's perpective.
         * 
         * @param   fiedOfView  Specifies an angle, as a degree between 0 and 180, for the field of view in three dimensions.
         * This value determines how strong the perspective transformation and distortion apply to a three-dimensional display object with a non-zero z-coordinate.
         * @param   rotationX   Indicates the x-axis rotation of the DisplayObject instance, in degrees, from its original orientation relative to the 3D parent container. 
         * Values from 0 to 180 represent clockwise rotation; values from 0 to -180 represent counterclockwise rotation. 
         * Values outside this range are added to or subtracted from 360 to obtain a value within the range.
         * @param   rotationY   Indicates the y-axis rotation of the DisplayObject instance, in degrees, from its original orientation relative to the 3D parent container. 
         * Values from 0 to 180 represent clockwise rotation; values from 0 to -180 represent counterclockwise rotation. 
         * Values outside this range are added to or subtracted from 360 to obtain a value within the range.
         * @param   rotationZ  Indicates the z-axis rotation of the DisplayObject instance, in degrees, from its original orientation relative to the 3D parent container. 
         * Values from 0 to 180 represent clockwise rotation; values from 0 to -180 represent counterclockwise rotation. 
         * Values outside this range are added to or subtracted from 360 to obtain a value within the range.
         */
        public function perspectiveProjection(fiedOfView:uint=90,rotationX:Number=-40,rotationY:Number=0,rotationZ:Number=0):void {         
            var perpective:PerspectiveProjection = new PerspectiveProjection;
            perpective.fieldOfView = fiedOfView;            
            _flashSprite.rotationX = rotationX;
            _flashSprite.rotationY = rotationY;
            _flashSprite.rotationZ = rotationZ;         
            _flashSprite.transform.perspectiveProjection = perpective;          
        }

[Gama11]

This is pretty awesome! :D There are a lot of cool things this could be used for, for example a transition effect between levels.

I've been playing around with this a bit. One thing I'd definitely change is the possibility of passing invalid values for fieldOfView, namely, everything smaller than 1 and bigger than 179, which causes a crash. That's why I find the description of fieldOfView a bit misleading - yeah, it says between 0 and 180, so it's technically not wrong - but it also doesn't explicitly state that those two numbers are excluded, so it could lead to quite a bit of confusion.

The crashes could be prevented really easily:

if (fieldOfView < 1) fieldOfView = 1;
else if (fieldOfView > 179) fieldOfView = 179;

Might also conisder throwing an error log in there (like, FlxG.log("FlxG.camera.perspectiveProjection: Invalid value of fieldOfView, but there's no real harm done in passing invalid parameters at this point when crashes aren't possible anymore.

Do you mind me submitting this to the Haxe-Port of flixel as well? (unless you want to do that yourself of course)

[flunardelli]

Pretty demo Gama !!!
I agree with your point and I will work I little more in error prevention.
Please keep free to share this idea with HaxeFlixel community.

[Dovyski]

This is really cool, @flunardelli ! The addition of perspectiveProjection() will allow the creation of several effects (Star Wars text anyone? :D)