Encode frame number in pixel data for pose sync

chrome/browser/android/vr_shell/vr_shell_renderer.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_renderer.h"
 
 #include "chrome/browser/android/vr_shell/vr_gl_util.h"
 #include "ui/gl/gl_bindings.h"
 
 namespace {
@@ skipping 279 matching lines @@
   glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_);
 
   glEnableVertexAttribArray(position_handle_);
   glEnableVertexAttribArray(tex_coord_handle_);
 
   glVertexAttribPointer(position_handle_, POSITION_ELEMENTS, GL_FLOAT, false,
       VERTEX_STRIDE, VOID_OFFSET(POSITION_OFFSET));
   glVertexAttribPointer(tex_coord_handle_, TEXCOORD_ELEMENTS, GL_FLOAT, false,
       VERTEX_STRIDE, VOID_OFFSET(TEXCOORD_OFFSET));
 
-  // Bind texture.
+  // Bind texture. Ideally this should be a 1:1 pixel copy. (Or even more
+  // ideally, a zero copy reuse of the texture.) For now, we're using an
+  // undersized render target for WebVR, so GL_LINEAR makes it look slightly
+  // less chunky. TODO(klausw): change this to GL_NEAREST once we're doing
+  // a 1:1 copy since that should be more efficient.
   glActiveTexture(GL_TEXTURE0);
   glBindTexture(GL_TEXTURE_EXTERNAL_OES, texture_handle);
+  glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+  glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+  glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
   glUniform1i(tex_uniform_handle_, 0);
 
   // TODO(bajones): 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);
@@ skipping 128 matching lines @@
 
 VrShellRenderer::VrShellRenderer()
     : textured_quad_renderer_(new TexturedQuadRenderer),
       webvr_renderer_(new WebVrRenderer),
       reticle_renderer_(new ReticleRenderer),
       laser_renderer_(new LaserRenderer) {}
 
 VrShellRenderer::~VrShellRenderer() = default;
 
 }  // namespace vr_shell