Introduce ChromeVR to Chrome on Android (behind a build flag)

chrome/browser/android/vr_shell/vr_shell.cc

+// 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 "chrome/browser/android/vr_shell/vr_shell.h"
+
+#include "chrome/browser/android/vr_shell/vr_shell_renderer.h"
+#include "chrome/browser/android/vr_shell/vr_util.h"
+#include "jni/VrShell_jni.h"
+#include "ui/gl/gl_bindings.h"
+#include "ui/gl/init/gl_factory.h"
+
+namespace vr_shell {
+
+namespace {
+// Constant taken from treasure_hunt demo.
+const long kPredictionTimeWithoutVsyncNanos = 50000000;
+
+const float kZNear = 0.1f;
+const float kZFar = 1000.0f;
+
+// Content rect in world coordinates. Height and width are currently supplied
+// as DrawFrame arguments.
+const gvr::Vec3f kContentRectPositionDefault = {0.0f, 0.0f, -1.0f};
+
+}  // namespace
+
+ContentRect::ContentRect() {
+  SetIdentity();
+}
+
+ContentRect::~ContentRect() {}
+
+void ContentRect::SetIdentity() {
+  transfrom_to_world.m[0][0] = 1;
+  transfrom_to_world.m[0][1] = 0;
+  transfrom_to_world.m[0][2] = 0;
+  transfrom_to_world.m[0][3] = 0;
+  transfrom_to_world.m[1][0] = 0;
+  transfrom_to_world.m[1][1] = 1;
+  transfrom_to_world.m[1][2] = 0;
+  transfrom_to_world.m[1][3] = 0;
+  transfrom_to_world.m[2][0] = 0;
+  transfrom_to_world.m[2][1] = 0;
+  transfrom_to_world.m[2][2] = 1;
+  transfrom_to_world.m[2][3] = 0;
+  transfrom_to_world.m[3][0] = 0;
+  transfrom_to_world.m[3][1] = 0;
+  transfrom_to_world.m[3][2] = 0;
+  transfrom_to_world.m[3][3] = 1;
+}
+
+void ContentRect::Translate(float x, float y, float z) {
+  transfrom_to_world.m[0][3] += x;
+  transfrom_to_world.m[1][3] += y;
+  transfrom_to_world.m[2][3] += z;
+}
+
+VrShell::VrShell(JNIEnv* env, jobject obj) {
+  j_vr_shell_.Reset(env, obj);
+}
+
+void VrShell::Destroy(JNIEnv* env,
+                      const base::android::JavaParamRef<jobject>& obj) {
+  delete this;
+}
+
+bool RegisterVrShell(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+VrShell::~VrShell() {}
+
+void VrShell::GvrInit(JNIEnv* env,
+                      const base::android::JavaParamRef<jobject>& obj,
+                      jlong native_gvr_api) {
+  gvr_api_ =
+      gvr::GvrApi::WrapNonOwned(reinterpret_cast<gvr_context*>(native_gvr_api));
+}
+
+void VrShell::InitializeGl(JNIEnv* env,
+                           const base::android::JavaParamRef<jobject>& obj,
+                           jint texture_data_handle) {
+  gl::init::InitializeGLOneOff();
+  gvr_api_->InitializeGl();
+  std::vector<gvr::BufferSpec> specs;
+  specs.push_back(gvr_api_->CreateBufferSpec());
+  render_size_ = specs[0].GetSize();
+  swap_chain_.reset(new gvr::SwapChain(gvr_api_->CreateSwapchain(specs)));
+  content_rect_.reset(new ContentRect());
+  content_rect_->content_texture_handle =
+      reinterpret_cast<int>(texture_data_handle);
+  vr_shell_renderer_.reset(new VrShellRenderer());
+  buffer_viewport_list_.reset(
+      new gvr::BufferViewportList(gvr_api_->CreateEmptyBufferViewportList()));
+  buffer_viewport_.reset(
+      new gvr::BufferViewport(gvr_api_->CreateBufferViewport()));
+}
+
+void VrShell::DrawFrame(JNIEnv* env,
+                        const base::android::JavaParamRef<jobject>& obj) {
+  buffer_viewport_list_->SetToRecommendedBufferViewports();
+  gvr::Frame frame = swap_chain_->AcquireFrame();
+  gvr::ClockTimePoint target_time = gvr::GvrApi::GetTimePointNow();
+  target_time.monotonic_system_time_nanos += kPredictionTimeWithoutVsyncNanos;
+  head_pose_ = gvr_api_->GetHeadPoseInStartSpace(target_time);
+
+  // Content area positioning.
+  content_rect_->SetIdentity();
+  content_rect_->Translate(kContentRectPositionDefault.x,
+                           kContentRectPositionDefault.y,
+                           kContentRectPositionDefault.z);
+
+  gvr::Mat4f left_eye_view_matrix =
+      MatrixMul(gvr_api_->GetEyeFromHeadMatrix(GVR_LEFT_EYE), head_pose_);
+  gvr::Mat4f right_eye_view_matrix =
+      MatrixMul(gvr_api_->GetEyeFromHeadMatrix(GVR_RIGHT_EYE), head_pose_);
+
+  // Bind back to the default framebuffer.
+  frame.BindBuffer(0);
+
+  // Use culling to remove back faces.
+  glEnable(GL_CULL_FACE);
+
+  // Enable depth testing.
+  glEnable(GL_DEPTH_TEST);
+  glEnable(GL_SCISSOR_TEST);
+
+  glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
+
+  // Enable transparency.
+  glEnable(GL_BLEND);
+  glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
+  buffer_viewport_list_->GetBufferViewport(GVR_LEFT_EYE,
+                                           buffer_viewport_.get());
+  DrawEye(left_eye_view_matrix, *buffer_viewport_);
+  buffer_viewport_list_->GetBufferViewport(GVR_RIGHT_EYE,
+                                           buffer_viewport_.get());
+  DrawEye(right_eye_view_matrix, *buffer_viewport_);
+
+  frame.Unbind();
+  frame.Submit(*buffer_viewport_list_, head_pose_);
+}
+
+void VrShell::DrawEye(const gvr::Mat4f& view_matrix,
+                      const gvr::BufferViewport& params) {
+  gvr::Recti pixel_rect =
+      CalculatePixelSpaceRect(render_size_, params.GetSourceUv());
+  glViewport(pixel_rect.left, pixel_rect.bottom,
+             pixel_rect.right - pixel_rect.left,
+             pixel_rect.top - pixel_rect.bottom);
+  glScissor(pixel_rect.left, pixel_rect.bottom,
+            pixel_rect.right - pixel_rect.left,
+            pixel_rect.top - pixel_rect.bottom);
+
+  view_matrix_ = view_matrix;
+
+  projection_matrix_ =
+      PerspectiveMatrixFromView(params.GetSourceFov(), kZNear, kZFar);
+
+  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+  DrawContentRect();
+}
+
+void VrShell::DrawContentRect() {
+  gvr::Mat4f content_rect_combined_matrix =
+      MatrixMul(view_matrix_, content_rect_->transfrom_to_world);
+  content_rect_combined_matrix =
+      MatrixMul(projection_matrix_, content_rect_combined_matrix);
+  vr_shell_renderer_->GetTexturedQuadRenderer()->Draw(
+      content_rect_->content_texture_handle, content_rect_combined_matrix);
+}
+
+void VrShell::OnPause(JNIEnv* env,
+                      const base::android::JavaParamRef<jobject>& obj) {
+  if (gvr_api_ == nullptr)
+    return;
+  gvr_api_->PauseTracking();
+}
+
+void VrShell::OnResume(JNIEnv* env,
+                       const base::android::JavaParamRef<jobject>& obj) {
+  if (gvr_api_ == nullptr)
+    return;
+  gvr_api_->RefreshViewerProfile();
+  gvr_api_->ResumeTracking();
+}
+
+// ----------------------------------------------------------------------------
+// Native JNI methods
+// ----------------------------------------------------------------------------
+
+jlong Init(JNIEnv* env, const base::android::JavaParamRef<jobject>& obj) {
+  VrShell* vrShell = new VrShell(env, obj);
+  return reinterpret_cast<intptr_t>(vrShell);
+}
+
+}  // namespace vr_shell