Equirectangular viewer Pixel Bender filter

EquirectangularViewer.pbk

/**
 * Equirectangular viewer
 * Last update: 6 March 2013
 *
 * Changelog:
 *		1.0 - Initial release
 *
 * Licensed under the MIT License:
 * http://www.opensource.org/licenses/mit-license.php
 *
 * 
 * Credits and references
 * ======================
 *
 * Inspired by LittlePlanets by subblue:
 * http://www.subblue.com/blog/2010/6/17/little_planets
 * 
 * A good selection of cosc-licensed equirectangular panorama source images can be found here:
 * http://www.flickr.com/photos/sbprzd/sets/72057594100163739/
 * http://www.flickr.com/photos/heiwa4126/sets/72157601609820530/
 * http://www.flickr.com/search/?q=equirectangular&z=e&l=deriv&ss=2&ct=5&mt=all&adv=1
 *
 *
 * Contact
 * =======
 *
 * This plugin is free to use for personal or commercial projects. 
 * I'd love to hear how you are using it so email me at aldo@fieldofview.com
 *
 */

#define TWOPI 6.283185307179586
#define PI	3.141592653589793

<languageVersion : 1.0;>

kernel EquirectangularViewer
<	namespace : "com.fieldofview";
	vendor : "Aldo Hoeben - www.fieldofview.com";
	version : 1;
	displayname: "Equirectangular Viewer";
	description : "Unwraps an equirectangular panorama image.";
>
{


	parameter float2 inputSize
	<
		minValue: float2(8, 4);
		maxValue: float2(4096, 4096);
		defaultValue: float2(2000, 1000);
		stepInterval: float2(1, 1);
		displayName: "Input image size";
		componentName: "Width|Height";
		aeDisplayName: "Input image size";
	>;

	parameter float2 outputSize
	<
		minValue: float2(8, 4);
		maxValue: float2(4096, 4096);
		defaultValue: float2(800, 400);
		stepInterval: float2(1, 1);
		displayName: "Output image size";
		componentName: "Width|Height";
		aeDisplayName: "Output image size";
	>;

	parameter float yaw
	<
		minValue: -180.0;
		maxValue: 180.0;
		defaultValue: 0.0;
		stepInterval: 0.5;
		displayName: "Yaw";
		aeDisplayName: "Yaw";
		aeUIControl:"aeAngle";
	>;

	parameter float pitch
	<
		minValue: -90.0;
		maxValue: 90.0;
		defaultValue: 0.0;
		stepInterval: 0.5;
		displayName: "Pitch";
		aeDisplayName: "Pitch";
		aeUIControl:"aeAngle";
	>;

	parameter float hfov
	<
		minValue: 1.0;
		maxValue: 170.0;
		defaultValue: 80.0;
		stepInterval: 1;
		displayName: "Horizontal Field of View";
		aeDisplayName: "Horizontal Field of View";
		aeUIControl:"aeAngle";
	>;

	input image4 src;
	output pixel4 dst;


	#if !AIF_FLASH_TARGET
	region needed(region outputRegion, imageRef inputRef) 
	{
		return region(float4(0, 0, inputSize.x, inputSize.y)); 
	}

	region changed(region outputRegion, imageRef inputRef) 
	{
		return region(float4(0, 0, outputSize.x, outputSize.y)); 
	}
	#endif



	float3x3 rotationMatrix(const float2 euler)
	{
		float2 se = sin(euler);
		float2 ce = cos(euler);
		
		return float3x3( 
			ce.x, 0.,-se.x,
			0.,   1., 0.,
			se.x, 0., ce.x
		) * float3x3( 
			1., 0.,   0.,
			0., ce.y,-se.y,
			0., se.y, ce.y
		);        
	}

	float3 toCartesian(float2 sphericalCoord)
	{
		return normalize(float3(sphericalCoord.x, sphericalCoord.y, 0.5 / tan(0.5 * radians(hfov))));
	}


	float2 toSpherical(float3 cartesianCoord)
	{
		float2 sphericalCoord = float2(
			atan(cartesianCoord.x, cartesianCoord.z),
			acos(cartesianCoord.y)
		);

		if(sphericalCoord.x < 0.0)
			sphericalCoord.x += TWOPI;
		
		return sphericalCoord;
	}

	void evaluatePixel() 
	{
		float2 sphericalCoord = outCoord() / outputSize - float2(0.5);
		sphericalCoord.y *= -outputSize.y / outputSize.x;        
		
		float3 cartesianCoord = rotationMatrix(float2(radians(yaw+180.), radians(pitch))) * toCartesian(sphericalCoord);

		dst = sampleLinear(src, toSpherical(cartesianCoord) / float2(TWOPI, PI) * (inputSize-float2(1.0))+float2(0.5));
	}
}