Added WebVR Render path to VrShell

chrome/browser/android/vr_shell/vr_shell_renderer.cc

Index: chrome/browser/android/vr_shell/vr_shell_renderer.cc
diff --git a/chrome/browser/android/vr_shell/vr_shell_renderer.cc b/chrome/browser/android/vr_shell/vr_shell_renderer.cc
index 7fb405fdd5b3717c19ce424240913e5adc7455bb..65bc41bf639e32eb98a8c1f6351b71cfecaa488e 100644
--- a/chrome/browser/android/vr_shell/vr_shell_renderer.cc
+++ b/chrome/browser/android/vr_shell/vr_shell_renderer.cc
@@ -25,8 +25,22 @@ const float kTexturedQuadTextureCoordinates[12] = {
     0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f};
 const int kTextureCoordinateDataSize = 2;
 
+const float kWebVrVertices[32] = {
+  //   x     y    u,   v
+    -1.f,  1.f, 0.f, 0.f, // Left Eye
+    -1.f, -1.f, 0.f, 1.f,
+     0.f, -1.f, 1.f, 1.f,
+     0.f,  1.f, 1.f, 0.f,
+
+     0.f,  1.f, 0.f, 0.f, // Right Eye
+     0.f, -1.f, 0.f, 1.f,
+     1.f, -1.f, 1.f, 1.f,
+     1.f,  1.f, 1.f, 0.f };
+const int kWebVrVerticesSize = sizeof(float) * 32;
+
 #define SHADER(Src) #Src
 #define OEIE_SHADER(Src) "#extension GL_OES_EGL_image_external : require\n" #Src
+#define VOID_OFFSET(x) reinterpret_cast<void*>(x)
 
 const char* GetShaderSource(ShaderID shader) {
   switch (shader) {
@@ -44,6 +58,26 @@ const char* GetShaderSource(ShaderID shader) {
             vec4 texture = texture2D(u_Texture, v_TexCoordinate);
             gl_FragColor = vec4(texture.r, texture.g, texture.b, 1.0);
           });
+    case vr_shell::ShaderID::WEBVR_VERTEX_SHADER:
+      return SHADER(
+          attribute vec2 a_Position;
+          attribute vec2 a_TexCoordinate;
+          uniform vec4 u_SrcRect;
+          varying vec2 v_TexCoordinate;
+
+          void main() {
+            v_TexCoordinate = u_SrcRect.xy + (a_TexCoordinate * u_SrcRect.zw);
+            gl_Position = vec4(a_Position, 0.0, 1.0);
+          });
+    case vr_shell::ShaderID::WEBVR_FRAGMENT_SHADER:
+      return OEIE_SHADER(
+          precision highp float;
+          uniform samplerExternalOES u_Texture;
+          varying vec2 v_TexCoordinate;
+
+          void main() {
+            gl_FragColor = texture2D(u_Texture, v_TexCoordinate);
+          });
     default:
       LOG(ERROR) << "Shader source requested for unknown shader";
       return "";
@@ -118,8 +152,109 @@ TexturedQuadRenderer::~TexturedQuadRenderer() {
   glDeleteShader(fragment_shader_handle_);
 }
 
+WebVrRenderer::WebVrRenderer() {
+  left_bounds_ = { 0.0f, 0.0f, 0.5f, 1.0f };
+  right_bounds_ = { 0.5f, 0.0f, 0.5f, 1.0f };
+
+  std::string error;
+  GLuint vertex_shader_handle = CompileShader(
+      GL_VERTEX_SHADER, GetShaderSource(WEBVR_VERTEX_SHADER), error);
+  if (vertex_shader_handle == 0) {
+    LOG(ERROR) << error;
+    exit(1);

[David Trainor- moved to gerrit, 2016/09/08 06:16:05]

Should we just do CHECK_EQ(0, vertex_shader_handle) << error; or something
similar?  Same for other cases.

It doesn't look like we really do exit() anywhere else in chrome/.

+  }
+  GLuint fragment_shader_handle = CompileShader(
+      GL_FRAGMENT_SHADER, GetShaderSource(WEBVR_FRAGMENT_SHADER), error);
+  if (fragment_shader_handle == 0) {
+    LOG(ERROR) << error;
+    exit(1);
+  }
+
+  program_handle_ = CreateAndLinkProgram(
+      vertex_shader_handle, fragment_shader_handle, 2, nullptr, error);
+  if (program_handle_ == 0) {
+    LOG(ERROR) << error;
+    exit(1);
+  }
+
+  // Once the program is linked the shader objects are no longer needed
+  glDeleteShader(vertex_shader_handle);
+  glDeleteShader(fragment_shader_handle);
+
+  tex_uniform_handle_ = glGetUniformLocation(program_handle_, "u_Texture");
+  src_rect_uniform_handle_ = glGetUniformLocation(program_handle_, "u_SrcRect");
+  position_handle_ = glGetAttribLocation(program_handle_, "a_Position");
+  texcoord_handle_ = glGetAttribLocation(program_handle_, "a_TexCoordinate");
+
+  // TODO: Figure out why this need to be restored.

[David Trainor- moved to gerrit, 2016/09/08 06:16:05]

Add ldap?

+  GLint old_buffer;
+  glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &old_buffer);
+
+  glGenBuffersARB(1, &vertex_buffer_);
+  glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_);
+  glBufferData(GL_ARRAY_BUFFER, kWebVrVerticesSize, kWebVrVertices,
+      GL_STATIC_DRAW);
+
+  glBindBuffer(GL_ARRAY_BUFFER, old_buffer);
+}
+
+/**
+ * Draw the WebVR frame

[David Trainor- moved to gerrit, 2016/09/08 06:16:05]

// instead of /*?  Style guide seems to push for that.

+ */
+void WebVrRenderer::Draw(int texture_handle) {
+  // TODO: Figure out why this need to be restored.

[David Trainor- moved to gerrit, 2016/09/08 06:16:05]

ldap, crbug?

+  GLint old_buffer;

[David Trainor- moved to gerrit, 2016/09/08 06:16:05]

A ScopedBufferRestore helper would be cool, but if this is just temporary until
you track down the missing rebind probably not worth it.

+  glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &old_buffer);
+
+  glUseProgram(program_handle_);
+
+  // Bind vertex attributes
+  glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_);
+
+  glEnableVertexAttribArray(position_handle_);
+  glEnableVertexAttribArray(texcoord_handle_);
+
+  glVertexAttribPointer(position_handle_, POSITION_ELEMENTS, GL_FLOAT, false,
+      VERTEX_STRIDE, VOID_OFFSET(POSITION_OFFSET));
+  glVertexAttribPointer(texcoord_handle_, TEXCOORD_ELEMENTS, GL_FLOAT, false,
+      VERTEX_STRIDE, VOID_OFFSET(TEXCOORD_OFFSET));
+
+  // Bind texture.
+  glActiveTexture(GL_TEXTURE0);
+  glBindTexture(GL_TEXTURE_EXTERNAL_OES, texture_handle);
+  glUniform1i(tex_uniform_handle_, 0);
+
+  // TODO: Should be able handle both eyes in a single draw call.
+  // Left eye
+  glUniform4fv(src_rect_uniform_handle_, 1, (float*)(&left_bounds_));
+  glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+
+  // Right eye
+  glUniform4fv(src_rect_uniform_handle_, 1, (float*)(&right_bounds_));
+  glDrawArrays(GL_TRIANGLE_FAN, 4, 4);
+
+  glDisableVertexAttribArray(position_handle_);
+  glDisableVertexAttribArray(texcoord_handle_);
+
+  glBindBuffer(GL_ARRAY_BUFFER, old_buffer);
+}
+
+void WebVrRenderer::UpdateTextureBounds(int eye, const gvr::Rectf& bounds) {
+  if (eye == 0) {
+    left_bounds_ = bounds;
+  } else if (eye == 1) {
+    right_bounds_ = bounds;
+  }
+}
+
+WebVrRenderer::~WebVrRenderer() {
+  glDeleteBuffersARB(1, &vertex_buffer_);
+  glDeleteProgram(program_handle_);
+}
+
 VrShellRenderer::VrShellRenderer()
-    : textured_quad_renderer_(new TexturedQuadRenderer) {}
+    : textured_quad_renderer_(new TexturedQuadRenderer),
+      webvr_renderer_(new WebVrRenderer) {}
 
 VrShellRenderer::~VrShellRenderer() {}