1 files changed, 113 insertions, 0 deletions
diff --git a/platform_tools/android/apps/arcore/src/main/cpp/background_renderer.cc b/platform_tools/android/apps/arcore/src/main/cpp/background_renderer.cc
new file mode 100644
index 0000000000..ea7a7c7eb1
--- /dev/null
+++ b/platform_tools/android/apps/arcore/src/main/cpp/background_renderer.cc
@@ -0,0 +1,113 @@
+/*
+ * Copyright 2017 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * 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.
+ */
+
+// This modules handles drawing the passthrough camera image into the OpenGL
+// scene.
+
+#include <type_traits>
+
+#include "background_renderer.h"
+
+namespace hello_ar {
+    namespace {
+// Positions of the quad vertices in clip space (X, Y, Z).
+        const GLfloat kVertices[] = {
+                -1.0f, -1.0f, 0.0f, +1.0f, -1.0f, 0.0f,
+                -1.0f, +1.0f, 0.0f, +1.0f, +1.0f, 0.0f,
+        };
+
+// UVs of the quad vertices (S, T)
+        const GLfloat kUvs[] = {
+                0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f,
+        };
+
+        constexpr char kVertexShader[] = R"(
+    attribute vec4 vertex;
+    attribute vec2 textureCoords;
+    varying vec2 v_textureCoords;
+    void main() {
+      v_textureCoords = textureCoords;
+      gl_Position = vertex;
+    })";
+
+        constexpr char kFragmentShader[] = R"(
+    #extension GL_OES_EGL_image_external : require
+    precision mediump float;
+    uniform samplerExternalOES texture;
+    varying vec2 v_textureCoords;
+    void main() {
+      gl_FragColor = texture2D(texture, v_textureCoords);
+    })";
+
+    }  // namespace
+
+    void BackgroundRenderer::InitializeGlContent() {
+        shader_program_ = util::CreateProgram(kVertexShader, kFragmentShader);
+
+        if (!shader_program_) {
+            LOGE("Could not create program.");
+        }
+
+        glGenTextures(1, &texture_id_);
+        glBindTexture(GL_TEXTURE_EXTERNAL_OES, texture_id_);
+        glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+        uniform_texture_ = glGetUniformLocation(shader_program_, "texture");
+        attribute_vertices_ = glGetAttribLocation(shader_program_, "vertex");
+        attribute_uvs_ = glGetAttribLocation(shader_program_, "textureCoords");
+    }
+
+    void BackgroundRenderer::Draw(const ArSession *session, const ArFrame *frame) {
+        static_assert(std::extent<decltype(kUvs)>::value == kNumVertices * 2,
+                      "Incorrect kUvs length");
+        static_assert(std::extent<decltype(kVertices)>::value == kNumVertices * 3,
+                      "Incorrect kVertices length");
+
+        // If display rotation changed (also includes view size change), we need to
+        // re-query the uv coordinates for the on-screen portion of the camera image.
+        int32_t geometry_changed = 0;
+        ArFrame_getDisplayGeometryChanged(session, frame, &geometry_changed);
+        if (geometry_changed != 0 || !uvs_initialized_) {
+            ArFrame_transformDisplayUvCoords(session, frame, kNumVertices * 2, kUvs,
+                                             transformed_uvs_);
+            uvs_initialized_ = true;
+        }
+        glUseProgram(shader_program_);
+        glDepthMask(GL_FALSE);
+
+        glUniform1i(uniform_texture_, 1);
+        glActiveTexture(GL_TEXTURE1);
+        glBindTexture(GL_TEXTURE_EXTERNAL_OES, texture_id_);
+
+        glEnableVertexAttribArray(attribute_vertices_);
+        glVertexAttribPointer(attribute_vertices_, 3, GL_FLOAT, GL_FALSE, 0,
+                              kVertices);
+
+        glEnableVertexAttribArray(attribute_uvs_);
+        glVertexAttribPointer(attribute_uvs_, 2, GL_FLOAT, GL_FALSE, 0,
+                              transformed_uvs_);
+
+        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+
+        glUseProgram(0);
+        glDepthMask(GL_TRUE);
+        util::CheckGlError("BackgroundRenderer::Draw() error");
+    }
+
+    GLuint BackgroundRenderer::GetTextureId() const { return texture_id_; }
+
+}  // namespace hello_ar