Method draw_rectangle

source/matplot/backend/opengl_embed.cpp:160–239

    }

    void opengl_embed::draw_rectangle(const double x1, const double x2,
                                           const double y1, const double y2,
                                           const std::array<float, 4> &color) {
        // Create and bind vertex array object
        unsigned int VAO;
        glGenVertexArrays(1, &VAO);
        glBindVertexArray(VAO);

        // Copy vertex data into the buffer's memory
        std::vector<float> vertices = {
            // x, y, z, r, g, b
            static_cast<float>(x2), static_cast<float>(y2), // top right
            static_cast<float>(x2), static_cast<float>(y1), // bottom right
            static_cast<float>(x1), static_cast<float>(y1), // bottom left
            static_cast<float>(x1), static_cast<float>(y2)  // top left
        };

        // Create and bind vertex buffer object
        unsigned int VBO;
        glGenBuffers(1, &VBO);
        glBindBuffer(GL_ARRAY_BUFFER, VBO);
        glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(float), vertices.data(), GL_DYNAMIC_DRAW);

        std::vector<unsigned int> indices = {  // note that we start from 0!
            0, 1, 3,   // first triangle
            1, 2, 3    // second triangle
        };

        // Element buffer
        unsigned int EBO;
        glGenBuffers(1, &EBO);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(unsigned int), indices.data(), GL_DYNAMIC_DRAW);

        // Set the vertex attributes pointers
        int vertex_attribute_location = 0;
        size_t stride = 2 * sizeof(float);
        glVertexAttribPointer(vertex_attribute_location, 2, GL_FLOAT, GL_FALSE, static_cast<GLsizei>(stride), (void *)0);
        glEnableVertexAttribArray(0);

        // Set the color attribute pointers
        // int color_attribute_location = 1;
        // glVertexAttribPointer(color_attribute_location, 3, GL_FLOAT, GL_FALSE, stride, (void *)(3*sizeof(float)));
        // glEnableVertexAttribArray(1);

        // Activate our shader program
        glUseProgram(draw_2d_single_color_shader_program_);

        // Set window size
        int windowHeightLocation = glGetUniformLocation(draw_2d_single_color_shader_program_, "windowHeight");
        if (windowHeightLocation == -1) {
            throw std::runtime_error("can't find uniform location");
        }
        glUniform1f(windowHeightLocation, static_cast<float>(height()));

        int windowWidthLocation = glGetUniformLocation(draw_2d_single_color_shader_program_, "windowWidth");
        if (windowWidthLocation == -1) {
            throw std::runtime_error("can't find uniform location");