third_party/WebKit/Source/modules/vr/VRFrameData.cpp

// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "modules/vr/VRFrameData.h"

#include "modules/vr/VREyeParameters.h"
#include "modules/vr/VRPose.h"

#include <cmath>

namespace blink {

// TODO(bajones): All of the matrix math here is temporary. It will be removed
// once the VRService has been updated to allow the underlying VR APIs to
// provide the projection and view matrices directly.

// Build a projection matrix from a field of view and near/far planes.
void projectionFromFieldOfView(DOMFloat32Array* outArray, VRFieldOfView* fov, float depthNear, float depthFar)
{
    float upTan = tanf(fov->upDegrees() * M_PI / 180.0);
    float downTan = tanf(fov->downDegrees() * M_PI / 180.0);
    float leftTan = tanf(fov->leftDegrees() * M_PI / 180.0);
    float rightTan = tanf(fov->rightDegrees() * M_PI / 180.0);
    float xScale = 2.0f / (leftTan + rightTan);
    float yScale = 2.0f / (upTan + downTan);

    float* out = outArray->data();
    out[0] = xScale;
    out[1] = 0.0f;
    out[2] = 0.0f;
    out[3] = 0.0f;
    out[4] = 0.0f;
    out[5] = yScale;
    out[6] = 0.0f;
    out[7] = 0.0f;
    out[8] = -((leftTan - rightTan) * xScale * 0.5);
    out[9] = ((upTan - downTan) * yScale * 0.5);
    out[10] = depthFar / (depthNear - depthFar);
    out[11] = -1.0f;
    out[12] = 0.0f;
    out[13] = 0.0f;
    out[14] = (depthFar * depthNear) / (depthNear - depthFar);
    out[15] = 0.0f;
}

// Create a matrix from a rotation and translation.
void matrixfromRotationTranslation(DOMFloat32Array* outArray, const mojo::WTFArray<float>& rotation, const mojo::WTFArray<float>& translation)
{
    // Quaternion math
    float x = rotation.is_null() ? 0.0f : rotation[0];
    float y = rotation.is_null() ? 0.0f : rotation[1];
    float z = rotation.is_null() ? 0.0f : rotation[2];
    float w = rotation.is_null() ? 1.0f : rotation[3];
    float x2 = x + x;
    float y2 = y + y;
    float z2 = z + z;

    float xx = x * x2;
    float xy = x * y2;
    float xz = x * z2;
    float yy = y * y2;
    float yz = y * z2;
    float zz = z * z2;
    float wx = w * x2;
    float wy = w * y2;
    float wz = w * z2;

    float* out = outArray->data();
    out[0] = 1 - (yy + zz);
    out[1] = xy + wz;
    out[2] = xz - wy;
    out[3] = 0;
    out[4] = xy - wz;
    out[5] = 1 - (xx + zz);
    out[6] = yz + wx;
    out[7] = 0;
    out[8] = xz + wy;
    out[9] = yz - wx;
    out[10] = 1 - (xx + yy);
    out[11] = 0;
    out[12] = translation.is_null() ? 0.0f : translation[0];
    out[13] = translation.is_null() ? 0.0f : translation[1];
    out[14] = translation.is_null() ? 0.0f : translation[2];
    out[15] = 1;
}

// Translate a matrix
void matrixTranslate(DOMFloat32Array* outArray, const DOMFloat32Array* translation)
{
    if (!translation)
        return;

    float x = translation->data()[0];
    float y = translation->data()[1];
    float z = translation->data()[2];

    float* out = outArray->data();
    out[12] = out[0] * x + out[4] * y + out[8] * z + out[12];
    out[13] = out[1] * x + out[5] * y + out[9] * z + out[13];
    out[14] = out[2] * x + out[6] * y + out[10] * z + out[14];
    out[15] = out[3] * x + out[7] * y + out[11] * z + out[15];
}

bool matrixInvert(DOMFloat32Array* outArray)
{
    float* out = outArray->data();
    float a00 = out[0];
    float a01 = out[1];
    float a02 = out[2];
    float a03 = out[3];
    float a10 = out[4];
    float a11 = out[5];
    float a12 = out[6];
    float a13 = out[7];
    float a20 = out[8];
    float a21 = out[9];
    float a22 = out[10];
    float a23 = out[11];
    float a30 = out[12];
    float a31 = out[13];
    float a32 = out[14];
    float a33 = out[15];

    float b00 = a00 * a11 - a01 * a10;
    float b01 = a00 * a12 - a02 * a10;
    float b02 = a00 * a13 - a03 * a10;
    float b03 = a01 * a12 - a02 * a11;
    float b04 = a01 * a13 - a03 * a11;
    float b05 = a02 * a13 - a03 * a12;
    float b06 = a20 * a31 - a21 * a30;
    float b07 = a20 * a32 - a22 * a30;
    float b08 = a20 * a33 - a23 * a30;
    float b09 = a21 * a32 - a22 * a31;
    float b10 = a21 * a33 - a23 * a31;
    float b11 = a22 * a33 - a23 * a32;

    // Calculate the determinant
    float det = b00 * b11 - b01 * b10 + b02 * b09 + b03 * b08 - b04 * b07 + b05 * b06;

    if (!det)
        return false;

    det = 1.0 / det;

    out[0] = (a11 * b11 - a12 * b10 + a13 * b09) * det;
    out[1] = (a02 * b10 - a01 * b11 - a03 * b09) * det;
    out[2] = (a31 * b05 - a32 * b04 + a33 * b03) * det;
    out[3] = (a22 * b04 - a21 * b05 - a23 * b03) * det;
    out[4] = (a12 * b08 - a10 * b11 - a13 * b07) * det;
    out[5] = (a00 * b11 - a02 * b08 + a03 * b07) * det;
    out[6] = (a32 * b02 - a30 * b05 - a33 * b01) * det;
    out[7] = (a20 * b05 - a22 * b02 + a23 * b01) * det;
    out[8] = (a10 * b10 - a11 * b08 + a13 * b06) * det;
    out[9] = (a01 * b08 - a00 * b10 - a03 * b06) * det;
    out[10] = (a30 * b04 - a31 * b02 + a33 * b00) * det;
    out[11] = (a21 * b02 - a20 * b04 - a23 * b00) * det;
    out[12] = (a11 * b07 - a10 * b09 - a12 * b06) * det;
    out[13] = (a00 * b09 - a01 * b07 + a02 * b06) * det;
    out[14] = (a31 * b01 - a30 * b03 - a32 * b00) * det;
    out[15] = (a20 * b03 - a21 * b01 + a22 * b00) * det;

    return true;
};

VRFrameData::VRFrameData()
    : m_timestamp(0.0)
{
    m_leftProjectionMatrix = DOMFloat32Array::create(16);
    m_leftViewMatrix = DOMFloat32Array::create(16);
    m_rightProjectionMatrix = DOMFloat32Array::create(16);
    m_rightViewMatrix = DOMFloat32Array::create(16);
    m_pose = VRPose::create();
}

bool VRFrameData::update(const device::blink::VRPosePtr& pose, VREyeParameters* leftEye, VREyeParameters* rightEye, float depthNear, float depthFar)
{
    if (!pose)
        return false;

    m_timestamp = pose->timestamp;

    // Build the projection matrices
    projectionFromFieldOfView(m_leftProjectionMatrix, leftEye->fieldOfView(), depthNear, depthFar);
    projectionFromFieldOfView(m_rightProjectionMatrix, rightEye->fieldOfView(), depthNear, depthFar);

    // Build the view matrices
    matrixfromRotationTranslation(m_leftViewMatrix, pose->orientation, pose->position);
    matrixTranslate(m_leftViewMatrix, leftEye->offset());
    if (!matrixInvert(m_leftViewMatrix))
        return false;

    matrixfromRotationTranslation(m_rightViewMatrix, pose->orientation, pose->position);
    matrixTranslate(m_rightViewMatrix, rightEye->offset());
    if (!matrixInvert(m_rightViewMatrix))
        return false;

    // Set the pose
    m_pose->setPose(pose);

    return true;
}

DEFINE_TRACE(VRFrameData)
{
    visitor->trace(m_leftProjectionMatrix);
    visitor->trace(m_leftViewMatrix);
    visitor->trace(m_rightProjectionMatrix);
    visitor->trace(m_rightViewMatrix);
    visitor->trace(m_pose);
}

} // namespace blink