diff options
Diffstat (limited to 'LibOVR/Src/OVR_StereoProjection.cpp')
| -rw-r--r-- | LibOVR/Src/OVR_StereoProjection.cpp | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/LibOVR/Src/OVR_StereoProjection.cpp b/LibOVR/Src/OVR_StereoProjection.cpp new file mode 100644 index 0000000..f0ae034 --- /dev/null +++ b/LibOVR/Src/OVR_StereoProjection.cpp @@ -0,0 +1,216 @@ +/************************************************************************************ + +Filename : OVR_StereoProjection.cpp +Content : Stereo rendering functions +Created : November 30, 2013 +Authors : Tom Fosyth + +Copyright : Copyright 2014 Oculus VR, LLC All Rights reserved. + +Licensed under the Oculus VR Rift SDK License Version 3.2 (the "License"); +you may not use the Oculus VR Rift SDK except in compliance with the License, +which is provided at the time of installation or download, or which +otherwise accompanies this software in either electronic or hard copy form. + +You may obtain a copy of the License at + +http://www.oculusvr.com/licenses/LICENSE-3.2 + +Unless required by applicable law or agreed to in writing, the Oculus VR SDK +distributed under the License is distributed on an "AS IS" BASIS, +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +See the License for the specific language governing permissions and +limitations under the License. + +*************************************************************************************/ + +#include "OVR_StereoProjection.h" + + +namespace OVR { + + +ScaleAndOffset2D CreateNDCScaleAndOffsetFromFov ( FovPort tanHalfFov ) +{ + float projXScale = 2.0f / ( tanHalfFov.LeftTan + tanHalfFov.RightTan ); + float projXOffset = ( tanHalfFov.LeftTan - tanHalfFov.RightTan ) * projXScale * 0.5f; + float projYScale = 2.0f / ( tanHalfFov.UpTan + tanHalfFov.DownTan ); + float projYOffset = ( tanHalfFov.UpTan - tanHalfFov.DownTan ) * projYScale * 0.5f; + + ScaleAndOffset2D result; + result.Scale = Vector2f(projXScale, projYScale); + result.Offset = Vector2f(projXOffset, projYOffset); + // Hey - why is that Y.Offset negated? + // It's because a projection matrix transforms from world coords with Y=up, + // whereas this is from NDC which is Y=down. + + return result; +} + + + +Matrix4f CreateProjection( bool rightHanded, bool isOpenGL, FovPort tanHalfFov, StereoEye /*eye*/, + float zNear /*= 0.01f*/, float zFar /*= 10000.0f*/, + bool flipZ /*= false*/, bool farAtInfinity /*= false*/) +{ + if(!flipZ && farAtInfinity) + { + //OVR_ASSERT_M(false, "Cannot push Far Clip to Infinity when Z-order is not flipped"); Assertion disabled because this code no longer has access to LibOVRKernel assertion functionality. + farAtInfinity = false; + } + + // A projection matrix is very like a scaling from NDC, so we can start with that. + ScaleAndOffset2D scaleAndOffset = CreateNDCScaleAndOffsetFromFov ( tanHalfFov ); + + float handednessScale = rightHanded ? -1.0f : 1.0f; + + Matrix4f projection; + // Produces X result, mapping clip edges to [-w,+w] + projection.M[0][0] = scaleAndOffset.Scale.x; + projection.M[0][1] = 0.0f; + projection.M[0][2] = handednessScale * scaleAndOffset.Offset.x; + projection.M[0][3] = 0.0f; + + // Produces Y result, mapping clip edges to [-w,+w] + // Hey - why is that YOffset negated? + // It's because a projection matrix transforms from world coords with Y=up, + // whereas this is derived from an NDC scaling, which is Y=down. + projection.M[1][0] = 0.0f; + projection.M[1][1] = scaleAndOffset.Scale.y; + projection.M[1][2] = handednessScale * -scaleAndOffset.Offset.y; + projection.M[1][3] = 0.0f; + + // Produces Z-buffer result - app needs to fill this in with whatever Z range it wants. + // We'll just use some defaults for now. + projection.M[2][0] = 0.0f; + projection.M[2][1] = 0.0f; + + if (farAtInfinity) + { + projection.M[2][2] = 0.0f; + projection.M[2][3] = zNear; + } + else + { + if (isOpenGL) + { + projection.M[2][2] = -handednessScale * (flipZ ? 1.0f : -1.0f) * (zNear + zFar) / (zFar - zNear); + projection.M[2][3] = -2.0f * ((flipZ ? -zFar : zFar) * zNear) / (zFar - zNear); + } + else + { + projection.M[2][2] = -handednessScale * (flipZ ? -zNear : zFar) / (zNear - zFar); + projection.M[2][3] = ((flipZ ? -zFar : zFar) * zNear) / (zNear - zFar); + } + } + + // Produces W result (= Z in) + projection.M[3][0] = 0.0f; + projection.M[3][1] = 0.0f; + projection.M[3][2] = handednessScale; + projection.M[3][3] = 0.0f; + + return projection; +} + + +Matrix4f CreateOrthoSubProjection ( bool /*rightHanded*/, StereoEye eyeType, + float tanHalfFovX, float tanHalfFovY, + float unitsX, float unitsY, + float distanceFromCamera, float interpupillaryDistance, + Matrix4f const &projection, + float zNear /*= 0.0f*/, float zFar /*= 0.0f*/, + bool flipZ /*= false*/, bool farAtInfinity /*= false*/) +{ + if(!flipZ && farAtInfinity) + { + //OVR_ASSERT_M(false, "Cannot push Far Clip to Infinity when Z-order is not flipped"); Assertion disabled because this code no longer has access to LibOVRKernel assertion functionality. + farAtInfinity = false; + } + + float orthoHorizontalOffset = interpupillaryDistance * 0.5f / distanceFromCamera; + switch ( eyeType ) + { + case StereoEye_Center: + orthoHorizontalOffset = 0.0f; + break; + case StereoEye_Left: + break; + case StereoEye_Right: + orthoHorizontalOffset = -orthoHorizontalOffset; + break; + default: + break; + } + + // Current projection maps real-world vector (x,y,1) to the RT. + // We want to find the projection that maps the range [-FovPixels/2,FovPixels/2] to + // the physical [-orthoHalfFov,orthoHalfFov] + // Note moving the offset from M[0][2]+M[1][2] to M[0][3]+M[1][3] - this means + // we don't have to feed in Z=1 all the time. + // The horizontal offset math is a little hinky because the destination is + // actually [-orthoHalfFov+orthoHorizontalOffset,orthoHalfFov+orthoHorizontalOffset] + // So we need to first map [-FovPixels/2,FovPixels/2] to + // [-orthoHalfFov+orthoHorizontalOffset,orthoHalfFov+orthoHorizontalOffset]: + // x1 = x0 * orthoHalfFov/(FovPixels/2) + orthoHorizontalOffset; + // = x0 * 2*orthoHalfFov/FovPixels + orthoHorizontalOffset; + // But then we need the sam mapping as the existing projection matrix, i.e. + // x2 = x1 * Projection.M[0][0] + Projection.M[0][2]; + // = x0 * (2*orthoHalfFov/FovPixels + orthoHorizontalOffset) * Projection.M[0][0] + Projection.M[0][2]; + // = x0 * Projection.M[0][0]*2*orthoHalfFov/FovPixels + + // orthoHorizontalOffset*Projection.M[0][0] + Projection.M[0][2]; + // So in the new projection matrix we need to scale by Projection.M[0][0]*2*orthoHalfFov/FovPixels and + // offset by orthoHorizontalOffset*Projection.M[0][0] + Projection.M[0][2]. + + float orthoScaleX = 2.0f * tanHalfFovX / unitsX; + float orthoScaleY = 2.0f * tanHalfFovY / unitsY; + Matrix4f ortho; + ortho.M[0][0] = projection.M[0][0] * orthoScaleX; + ortho.M[0][1] = 0.0f; + ortho.M[0][2] = 0.0f; + ortho.M[0][3] = -projection.M[0][2] + ( orthoHorizontalOffset * projection.M[0][0] ); + + ortho.M[1][0] = 0.0f; + ortho.M[1][1] = -projection.M[1][1] * orthoScaleY; // Note sign flip (text rendering uses Y=down). + ortho.M[1][2] = 0.0f; + ortho.M[1][3] = -projection.M[1][2]; + + const float zDiff = zNear - zFar; + if (fabsf(zDiff) < 0.001f) + { + ortho.M[2][0] = 0.0f; + ortho.M[2][1] = 0.0f; + ortho.M[2][2] = 0.0f; + ortho.M[2][3] = flipZ ? zNear : zFar; + } + else + { + ortho.M[2][0] = 0.0f; + ortho.M[2][1] = 0.0f; + + if(farAtInfinity) + { + ortho.M[2][2] = 0.0f; + ortho.M[2][3] = zNear; + } + else if (zDiff != 0.0f) + { + ortho.M[2][2] = (flipZ ? zNear : zFar) / zDiff; + ortho.M[2][3] = ((flipZ ? -zFar : zFar) * zNear) / zDiff; + } + } + + // No perspective correction for ortho. + ortho.M[3][0] = 0.0f; + ortho.M[3][1] = 0.0f; + ortho.M[3][2] = 0.0f; + ortho.M[3][3] = 1.0f; + + return ortho; +} + + + +} //namespace OVR + + |