/**
* Copyright 2014 JogAmp Community. All rights reserved.
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* Redistribution and use in source and binary forms, with or without modification, are
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* 3. Compliance with Oculus VR RIFT SDK LICENSE (see below)
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* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JogAmp Community OR
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*
* This file contains mathematical equations, comments and algorithms
* used in the Oculus VR RIFT SDK 0.3.2.
*
* Due to unknown legal status, the 'requested' Copyright tag and disclaimer
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* Copyright © 2014 Oculus VR, Inc. All rights reserved
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* Oculus VR, Inc. Software Development Kit License Agreement
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* Human-Readable Summary*:
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* You are Free to:
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* * - This human-readable Summary is not a license. It is simply a convenient
* reference for understanding the full Oculus VR Rift SDK License Agreement.
* The Summary is written as a user-friendly interface to the full Oculus VR Rift
* SDK License below. This Summary itself has no legal value, and its contents do
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package jogamp.opengl.oculusvr.stereo.lense;
import com.jogamp.math.VectorUtil;
import com.jogamp.nativewindow.util.DimensionImmutable;
import com.jogamp.opengl.util.stereo.generic.GenericStereoDeviceConfig;
public class DistortionSpec {
public DistortionSpec(final LensConfig lens) {
this.lens = lens;
this.pixelsPerTanAngleAtCenter = new float[2];
this.tanEyeAngleScale = new float[2];
this.lensCenter = new float[2];
}
private static final float[] quaterHalf = new float[] { 0.25f, 0.5f };
final LensConfig lens;
final float[] pixelsPerTanAngleAtCenter;
final float[] tanEyeAngleScale;
final float[] lensCenter;
public static DistortionSpec[] CalculateDistortionSpec (final GenericStereoDeviceConfig deviceConfig, final float[] eyeReliefInMeters) {
final DistortionSpec[] result = new DistortionSpec[2];
/// FIXME: Add 'pluggable' lense configuration
final LensConfig[] lensConfig = LensConfig.GenerateLensConfigFromEyeRelief(eyeReliefInMeters, LensConfig.DistortionEquation.CatmullRom10);
result[0] = CalculateDistortionSpec (deviceConfig, 0, eyeReliefInMeters[0], lensConfig[0]);
result[1] = CalculateDistortionSpec (deviceConfig, 1, eyeReliefInMeters[1], lensConfig[1]);
return result;
}
private static DistortionSpec CalculateDistortionSpec (final GenericStereoDeviceConfig deviceConfig, final int eyeName,
final float eyeReliefInMeters, final LensConfig lensConfig) {
// From eye relief, IPD and device characteristics, we get the distortion mapping.
// This distortion does the following things:
// 1. It undoes the distortion that happens at the edges of the lens.
// 2. It maps the undistorted field into "retina" space.
// So the input is a pixel coordinate - the physical pixel on the display itself.
// The output is the real-world direction of the ray from this pixel as it comes out of the lens and hits the eye.
// However we typically think of rays "coming from" the eye, so the direction (TanAngleX,TanAngleY,1) is the direction
// that the pixel appears to be in real-world space, where AngleX and AngleY are relative to the straight-ahead vector.
// If your renderer is a raytracer, you can use this vector directly (normalize as appropriate).
// However in standard rasterisers, we have rendered a 2D image and are putting it in front of the eye,
// so we then need a mapping from this space to the [-1,1] UV coordinate space, which depends on exactly
// where "in space" the app wants to put that rendertarget.
// Where in space, and how large this rendertarget is, is completely up to the app and/or user,
// though of course we can provide some useful hints.
// TODO: Use IPD and eye relief to modify distortion (i.e. non-radial component)
// TODO: cope with lenses that don't produce collimated light.
// This means that IPD relative to the lens separation changes the light vergence,
// and so we actually need to change where the image is displayed.
final DistortionSpec localDistortion = new DistortionSpec(lensConfig);
final DimensionImmutable resolutionInPixels = deviceConfig.surfaceSizeInPixels;
final float[] pixelsPerMeter = new float[] { resolutionInPixels.getWidth() / deviceConfig.screenSizeInMeters[0],
resolutionInPixels.getHeight() / deviceConfig.screenSizeInMeters[1] };
VectorUtil.scaleVec2(localDistortion.pixelsPerTanAngleAtCenter, pixelsPerMeter, localDistortion.lens.MetersPerTanAngleAtCenter);
// Same thing, scaled to [-1,1] for each eye, rather than pixels.
VectorUtil.scaleVec2(localDistortion.tanEyeAngleScale, quaterHalf,
VectorUtil.divVec2(new float[2], deviceConfig.screenSizeInMeters, localDistortion.lens.MetersPerTanAngleAtCenter) );
// <--------------left eye------------------><-ScreenGapSizeInMeters-><--------------right eye----------------->
// <------------------------------------------ScreenSizeInMeters.Width----------------------------------------->
// <------------interpupillaryDistanceInMeters-------------->
// <--centerFromLeftInMeters->
// ^
// Center of lens
// Find the lens centers in scale of [-1,+1] (NDC) in left eye.
final float visibleWidthOfOneEye = 0.5f * ( deviceConfig.screenSizeInMeters[0] );
final float centerFromLeftInMeters = ( deviceConfig.screenSizeInMeters[0] - deviceConfig.interpupillaryDistanceInMeters ) * 0.5f;
localDistortion.lensCenter[0] = ( centerFromLeftInMeters / visibleWidthOfOneEye ) * 2.0f - 1.0f;
localDistortion.lensCenter[1] = ( deviceConfig.pupilCenterFromScreenTopInMeters / deviceConfig.screenSizeInMeters[1] ) * 2.0f - 1.0f;
if ( 1 == eyeName ) {
localDistortion.lensCenter[0] = -localDistortion.lensCenter[0];
}
return localDistortion;
}
}