/*
 * 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.
 */

#include "point_cloud_renderer.h"
#include "util.h"

namespace hello_ar {
    namespace {
        constexpr char kVertexShader[] = R"(
    attribute vec4 vertex;
    uniform mat4 mvp;
    void main() {
      gl_PointSize = 5.0;
      // Pointcloud vertex's w component is confidence value.
      // Not used in renderer.
      gl_Position = mvp * vec4(vertex.xyz, 1.0);
    })";

        constexpr char kFragmentShader[] = R"(
    precision lowp float;
    void main() {
      gl_FragColor = vec4(0.1215, 0.7372, 0.8235, 1.0);
    })";
    }  // namespace

    void PointCloudRenderer::InitializeGlContent() {
        shader_program_ = util::CreateProgram(kVertexShader, kFragmentShader);

        CHECK(shader_program_);

        attribute_vertices_ = glGetAttribLocation(shader_program_, "vertex");
        uniform_mvp_mat_ = glGetUniformLocation(shader_program_, "mvp");

        util::CheckGlError("point_cloud_renderer::InitializeGlContent()");
    }

    void PointCloudRenderer::Draw(glm::mat4 mvp_matrix, ArSession *ar_session,
                                  ArPointCloud *ar_point_cloud) const {
        CHECK(shader_program_);

        glUseProgram(shader_program_);

        int32_t number_of_points = 0;
        ArPointCloud_getNumberOfPoints(ar_session, ar_point_cloud, &number_of_points);
        if (number_of_points <= 0) {
            return;
        }

        const float *point_cloud_data;
        ArPointCloud_getData(ar_session, ar_point_cloud, &point_cloud_data);

        glUniformMatrix4fv(uniform_mvp_mat_, 1, GL_FALSE, glm::value_ptr(mvp_matrix));

        glEnableVertexAttribArray(attribute_vertices_);
        glVertexAttribPointer(attribute_vertices_, 4, GL_FLOAT, GL_FALSE, 0,
                              point_cloud_data);

        glDrawArrays(GL_POINTS, 0, number_of_points);

        glUseProgram(0);
        util::CheckGlError("PointCloudRenderer::Draw");
    }

}  // namespace hello_ar