ex08_elements.cpp

#include <application.hpp>
#include <shader.hpp>
#include <iostream>


class ElementsApplication : public our::Application {

    our::ShaderProgram program;
    GLuint vertex_array = 0, vertex_buffer = 0, element_buffer = 0;

    our::WindowConfiguration getWindowConfiguration() override {
        return { "Interleaved Attributes", {1280, 720}, false };
    }

    void onInitialize() override {
        program.create();
        program.attach("assets/shaders/ex06_multiple_attributes/multiple_attributes.vert", GL_VERTEX_SHADER);
        program.attach("assets/shaders/ex04_varyings/varying_color.frag", GL_FRAGMENT_SHADER);
        program.link();

        glGenVertexArrays(1, &vertex_array);
        glBindVertexArray(vertex_array);

        glGenBuffers(1, &vertex_buffer);
        glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);

        struct Vertex {
            glm::vec3 position;
            glm::vec<4, glm::uint8, glm::defaultp> color;
        };

        Vertex data[] = {
                {{-0.5, -0.5, 0.0},{255, 0, 0, 255}},
                {{0.5, -0.5, 0.0},{0, 255, 0, 255}},
                {{0.5, 0.5, 0.0},{0, 0, 255, 255}},
                {{-0.5, 0.5, 0.0},{255, 255, 0, 255}}
        };

        glBufferData(GL_ARRAY_BUFFER, 4*sizeof(Vertex), data, GL_STATIC_DRAW);

        glVertexAttribPointer(0, 3, GL_FLOAT, false, sizeof(Vertex), (void*)offsetof(Vertex, position));
        glEnableVertexAttribArray(0);
        glVertexAttribPointer(1, 4, GL_UNSIGNED_BYTE, true, sizeof(Vertex), (void*)offsetof(Vertex, color));
        glEnableVertexAttribArray(1);

        glGenBuffers(1, &element_buffer);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, element_buffer);

        uint16_t elements[] = {
                0, 1, 2,
                2, 3, 0
        };

        glBufferData(GL_ELEMENT_ARRAY_BUFFER, 6*sizeof(uint16_t), elements, GL_STATIC_DRAW);

        glBindVertexArray(0);

        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    }

    void onDraw(double deltaTime) override {
        glClear(GL_COLOR_BUFFER_BIT);
        glUseProgram(program);
        glBindVertexArray(vertex_array);
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, (void*)0);
        glBindVertexArray(0);
    }

    void onDestroy() override {
        program.destroy();
        glDeleteVertexArrays(1, &vertex_array);
        glDeleteBuffers(1, &vertex_buffer);
        glDeleteBuffers(1, &element_buffer);
    }

};

int main(int argc, char** argv) {
    return ElementsApplication().run();
}