maybe-another-gl/src/renderer.cpp

#include "renderer.h"

#include <glad/glad.h>
#include <glm/gtc/matrix_transform.hpp>

Renderer::Renderer(Shader shader, glm::vec2 position, glm::vec2 size, float rotate, glm::vec3 color)
    : m_shader(shader), m_position(position), m_size(size), m_rotate(rotate), m_color(color) {

    this->init();
}

void Renderer::draw() {
	this->m_shader.use();

	glm::mat4 model = glm::mat4(1.0f);
	model = glm::translate(model, glm::vec3(m_position, 0.0f));


    model = glm::translate(model, glm::vec3(0.5f * m_size.x, 0.5f * m_size.y, 0.0f)); // move origin of rotation to center of quad
    model = glm::rotate(model, glm::radians(m_rotate), glm::vec3(0.0f, 0.0f, 1.0f)); // then rotate
    model = glm::translate(model, glm::vec3(-0.5f * m_size.x, -0.5f * m_size.y, 0.0f)); // move origin back

    model = glm::scale(model, glm::vec3(m_size, 1.0f)); // last scale

    this->m_shader.setMatrix4("model", model);

    // render textured quad
    this->m_shader.setVector3f("spriteColor", m_color);

    //glActiveTexture(GL_TEXTURE0);
    //texture.Bind();

    glBindVertexArray(this->m_vao);
    glDrawArrays(GL_TRIANGLES, 0, 6);
    glBindVertexArray(0);
}

void Renderer::init()
{
    // configure VAO/VBO
    unsigned int VBO;
    float vertices[] = {
        // pos      // tex
        0.0f, 1.0f, 0.0f, 1.0f,
        1.0f, 0.0f, 1.0f, 0.0f,
        0.0f, 0.0f, 0.0f, 0.0f,

        0.0f, 1.0f, 0.0f, 1.0f,
        1.0f, 1.0f, 1.0f, 1.0f,
        1.0f, 0.0f, 1.0f, 0.0f
    };

    glGenVertexArrays(1, &this->m_vao);
    glGenBuffers(1, &VBO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    glBindVertexArray(this->m_vao);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void*)0);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindVertexArray(0);
}