Renderer.cpp

//
// Created by simrat39 on 12/29/23.
//

#include "Renderer.hpp"
#include "ConfigManager.hpp"
#include "constants.hpp"
#include <epoxy/gl.h>
#include <string>
#include <vector>

Renderer::Renderer() {
  auto &cfg = ConfigManager::get_instance();

  width = cfg.get_or_default("width", DEFAULT_WIDTH);
  height = cfg.get_or_default("height", DEFAULT_HEIGHT);
  bars = cfg.get_or_default("bars", NUM_BARS_MAX);
}

void Renderer::pre_render() {
  shader = new Shader{
      "/usr/share/cavaland/shaders/vertex.glsl",
      ConfigManager::get_instance()
          .get_or_default("shader",
                          "/usr/share/cavaland/shaders/bars/x_gradient.glsl")
          .c_str(),
  };

  // Pre Draw
  std::vector<GLfloat> vertices = {
      // x   y       z
      RIGHT, TOP,    0.f, // top right
      RIGHT, BOTTOM, 0.f, // bottom right
      LEFT,  BOTTOM, 0.f, // bottom left
      LEFT,  TOP,    0.f  // top left
  };

  std::vector<GLuint> indices = {0, 1, 3, 1, 2, 3};

  // VAO
  glGenVertexArrays(1, &VAO);
  glBindVertexArray(VAO);

  // VBO
  glGenBuffers(1, &VBO);
  glBindBuffer(GL_ARRAY_BUFFER, VBO);
  glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(GLfloat),
               vertices.data(), GL_STATIC_DRAW);

  // EBO
  // This is after VAO cuz it needs the VAO
  glGenBuffers(1, &EBO);
  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
  glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(GLuint),
               indices.data(), GL_STATIC_DRAW);

  // This is after VBO cuz it needs the VBO
  glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), nullptr);
  glEnableVertexAttribArray(0);

  shader->register_uniform("heights");
  shader->register_uniform("width");
  shader->register_uniform("height");
  shader->register_uniform("num_bars");

  glViewport(0, 0, width, height);
}

void Renderer::render(float *data) {
  glClear(GL_COLOR_BUFFER_BIT);

  shader->use();

  auto &cfg = ConfigManager::get_instance();

  shader->set_float_uniform("width", width);
  shader->set_float_uniform("height", height);
  shader->set_uint_uniform("num_bars", bars);
  // Maybe use a texture for this
  shader->set_float_array_uniform("heights", bars, data);

  glBindVertexArray(VAO);
  glDrawElements(GL_TRIANGLES, 8, GL_UNSIGNED_INT, nullptr);
}