engineer-thesis-WUT/Engine/engine/draw.cpp

// "Copyright [2023] <Krzysztof Rudnicki>"
#ifndef DRAW_CPP
#define DRAW_CPP
#include "./draw.hpp"

#include <glad/glad.h>
#include <GLFW/glfw3.h>

#include <cmath>
#include <filesystem>
#include <iostream>
#include <utility>

#include "./constants.hpp"
#include "./misc.hpp"
#include "./renderLoop.hpp"
#include "./shader.hpp"
#include "./shaders.hpp"
#include "./stb_image.h"
#include "./textures.hpp"

drawFigureReturn drawFigure(const int whatToDraw) {
  switch (whatToDraw) {
    case 0:
      return drawTriangleClass(constants::VERTEX_SHADER_SOURCE_FILENAME,
                               constants::FRAGMENT_SHADER_SOURCE_FILENAME,
                               constants::TRIANGLE_VERTICES,
                               constants::TRIANGLE_VERTICES_SIZE);
    case 1:
      return drawSquare(
          constants::SQUARE_VERTICES, constants::SQUARE_VERTICES_SIZE,
          constants::SQUARE_INDICES, constants::SQUARE_INDICES_SIZE,
          constants::VERTEX_SHADER_SOURCE, constants::FRAGMENT_SHADER_SOURCE);
    case 2:
      // Try to draw 2 triangles next to each other
      // using glDrawArrays by adding more vertices to your data.
      return drawTriangleClass(constants::VERTEX_SHADER_SOURCE_FILENAME,
                               constants::FRAGMENT_SHADER_SOURCE_FILENAME,
                               constants::TRIANGLES_VERTICES,
                               constants::TRIANGLES_VERTICES_SIZE);
    case 3:
      drawTriangleClass(constants::VERTEX_SHADER_SOURCE_FILENAME,
                        constants::FRAGMENT_SHADER_SOURCE_FILENAME,
                        constants::TRIANGLE_ONE, constants::TRIANGLE_ONE_SIZE);
      // Now create the same 2 triangles
      // using two different VAOs and VBOs for their data
      return drawTriangleClass(constants::VERTEX_SHADER_SOURCE_FILENAME,
                               constants::FRAGMENT_SHADER_SOURCE_FILENAME,
                               constants::TRIANGLE_TWO,
                               constants::TRIANGLE_TWO_SIZE);
    case 4:
      drawTriangleClass(constants::VERTEX_SHADER_SOURCE_FILENAME,
                        constants::FRAGMENT_SHADER_SOURCE_FILENAME,
                        constants::TRIANGLE_ONE, constants::TRIANGLE_ONE_SIZE);
      /*
      Create two shader programs where
      the second program uses a different
      fragment shader that outputs the color yellow;
      draw both triangles again where one outputs the color yellow
      */
      return drawTriangleClass(
          constants::VERTEX_SHADER_SOURCE_FILENAME,
          constants::FRAGMENT_SHADER_SOURCE_YELLOW_FILENAME,
          constants::TRIANGLE_TWO, constants::TRIANGLE_TWO_SIZE);
    case 5:
      // Get color from vertex shader to fragment shader
      return drawTriangleClass(
          constants::VERTEX_SHADER_COLOR_FILENAME,
          constants::FRAGMENT_SHADER_COLOR_FROM_VERTEX_FILENAME,
          constants::TRIANGLE_VERTICES, constants::TRIANGLE_VERTICES_SIZE);
    case 6:
      // set color from opengl code to uniform value in fragment shader
      return drawTriangleClass(constants::VERTEX_SHADER_COLOR_FILENAME,
                               constants::FRAGMENT_SHADER_UNIFORMS_FILENAME,
                               constants::TRIANGLE_VERTICES,
                               constants::TRIANGLE_VERTICES_SIZE);
    case 7:
      // set color from opengl code to uniform value in fragment shader
      return drawTriangleClass(
          constants::VERTEX_SHADER_VERTICE_COLOR_FILENAME,
          constants::FRAGMENT_SHADER_COLOR_FROM_VERTEX_FILENAME,
          constants::TRIANGLE_COLORS, constants::TRIANGLE_COLORS_SIZE, true);
    case 8:
      // upside down triangle
      return drawTriangleClass(constants::VERTEX_SHADER_UPSIDE_DOWN_FILENAME,
                               constants::FRAGMENT_SHADER_SOURCE_FILENAME,
                               constants::TRIANGLE_VERTICES,
                               constants::TRIANGLE_VERTICES_SIZE);
    case 9: {
      // offset triangle
      offsetsStruct offsets = offsetsStruct();
      offsets.xOffset = 0.5f;
      return drawTriangleClass(constants::VERTEX_SHADER_OFFSET_FILENAME,
                               constants::FRAGMENT_SHADER_SOURCE_FILENAME,
                               constants::TRIANGLE_VERTICES,
                               constants::TRIANGLE_VERTICES_SIZE, false, false,
                               offsets);
    }
    case 10:
      return drawTriangleClass(constants::VERTEX_SHADER_TASK_THREE_FILENAME,
                               constants::FRAGMENT_SHADER_TASK_THREE_FILENAME,
                               constants::TRIANGLE_VERTICES,
                               constants::TRIANGLE_VERTICES_SIZE);
    case constants::MAX_DRAW_CALL:
      return drawDebilMode(
          constants::VERTEX_SHADER_TEXTURE_FILENAME,
          constants::FRAGMENT_SHADER_TEXTURE_FILENAME,
          constants::TEXTURE_VERTICES, constants::TEXTURE_VERTICES_SIZE,
          constants::TEXTURE_INDICES, constants::TEXTURE_INDICES_SIZE);
    default:
      throw "No function for this draw call";
  }
}

unsigned int getShaderProgram(const char* vertexShaderSource,
                              const char* fragmentShaderSource) {
  const std::pair<unsigned int, unsigned int> shaders =
      compileShaders(vertexShaderSource, fragmentShaderSource);
  if (shaders.first == 0 || shaders.second == 0) return 0;

  const unsigned int shaderProgram =
      linkShaderObjectsShaderProgram(shaders.first, shaders.second);

  if (shaderProgram == 0) return 0;
  return shaderProgram;
}

void setOffsets(Shader shader, const offsetsStruct offsets) {
  shader.setFloat("xOffset", offsets.xOffset);
  shader.setFloat("yOffset", offsets.yOffset);
  shader.setFloat("zOffset", offsets.zOffset);
}

drawFigureReturn drawTriangleClass(const char* vertexPath,
                                   const char* fragmentPath,
                                   const float triangleVertices[],
                                   const size_t triangleVerticesSize,
                                   const bool colorIncluded,
                                   const bool textureIncluded,
                                   const offsetsStruct offsets) {
  // In your CPP file:
  // ======================
  // float offset = 0.5f;

  Shader ourShader(vertexPath, fragmentPath);
  ourShader.use();
  setOffsets(ourShader, offsets);

  const unsigned int vertexBufferObject = copyVerticesMemory(
      triangleVertices, triangleVerticesSize, GL_ARRAY_BUFFER);
  const unsigned int vertexArrayObject = generateBindVAO();
  copyVerticesArray(vertexBufferObject, triangleVertices, triangleVerticesSize,
                    GL_ARRAY_BUFFER);
  // set vertex attribute pointers
  configureVertexAttribute(colorIncluded, textureIncluded);
  doDrawArrays(ourShader.ID, vertexArrayObject, GL_TRIANGLES, 0,
               triangleVerticesSize);
  drawFigureReturn newReturn;
  newReturn.success = 0;
  newReturn.VAO = vertexArrayObject;
  newReturn.VBO = vertexBufferObject;
  newReturn.EBO = 0;
  return newReturn;
}

drawFigureReturn drawSquare(
    const float squareVertices[], const size_t squareVerticesSize,
    const unsigned int squareIndices[], const size_t squareIndicesSize,
    const char* vertexShaderSource, const char* fragmentShaderSource,
    const bool colorIncluded, const bool textureIncluded,
    const offsetsStruct offsets) {
  const unsigned int shaderProgram =
      getShaderProgram(vertexShaderSource, fragmentShaderSource);
  drawFigureReturn newReturn = drawFigureReturn();
  if (shaderProgram == 0) {
    newReturn.success = -1;
    return newReturn;
  }
  const unsigned int VAO = generateBindVAO();
  copyVerticesMemory(squareVertices, squareVerticesSize, GL_ARRAY_BUFFER);
  copyVerticesMemory(squareIndices, squareIndicesSize, GL_ELEMENT_ARRAY_BUFFER);

  // set vertex attribute pointers
  configureVertexAttribute(colorIncluded, textureIncluded);

  doDrawElements(shaderProgram, VAO, GL_TRIANGLES, GL_UNSIGNED_INT,
                 squareIndicesSize);
  newReturn.success = 0;
  newReturn.VAO = VAO;
  return newReturn;
}

drawFigureReturn drawDebilMode(const char* vertexPath, const char* fragmentPath,
                               const float vertices[],
                               const size_t verticesSize,
                               const unsigned int indices[],
                               const size_t indicesSize) {
  // https://stackoverflow.com/questions/33883609/opengl-linker-error-linking-with-uncompiled-shader
  Shader ourShader(constants::VERTEX_SHADER_TEXTURE_FILENAME,
                   constants::FRAGMENT_SHADER_TEXTURE_FILENAME);

  unsigned int VAO = generateBindVAO();
  unsigned int VBO =
      copyVerticesMemory(vertices, verticesSize, GL_ARRAY_BUFFER);
  unsigned int EBO =
      copyVerticesMemory(indices, indicesSize, GL_ELEMENT_ARRAY_BUFFER);

  configureVertexAttribute(true, true);

  unsigned int texture1 = loadAndCreateTexture("assets/container.png", true);
  unsigned int texture2 = loadAndCreateTexture("assets/awesomeface.png", false);

  ourShader.use();  // don't forget to activate/use
  // the shader before setting uniforms!
  // set it via the texture class
  ourShader.setInt("texture1", 0);
  ourShader.setInt("texture2", 1);

  activateAndBindTextures(texture1, GL_TEXTURE0);
  activateAndBindTextures(texture2, GL_TEXTURE1);

  glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);

  drawFigureReturn newReturn;
  newReturn.success = 0;
  newReturn.VAO = VAO;
  newReturn.VBO = VBO;
  newReturn.EBO = EBO;
  return newReturn;
}

void doDrawElements(const unsigned int shaderProgram,
                    const unsigned int vertexArrayObject,
                    const GLenum drawArrayMode, const GLenum drawType,
                    const int numberOfElementsToDraw) {
  glUseProgram(shaderProgram);
  glBindVertexArray(vertexArrayObject);
  glDrawElements(drawArrayMode, numberOfElementsToDraw, drawType, 0);
  glBindVertexArray(0);
}

void updateUniformColor(const unsigned int shaderProgram,
                        const GLchar* uniformName) {
  // update the uniform color
  const float timeValue = glfwGetTime();  // retrieve running time
  const float greenValue = sin(timeValue) / 2.0f + 0.5f;
  // vary the color from 0.0 to 1.0 using sin
  // query the location of our uniform
  const int vertexColorLocation =
      glGetUniformLocation(shaderProgram, uniformName);
  // if glGetUniformLocation returns -1 it could not find the location
  if (vertexColorLocation != -1) {
    glUniform4f(vertexColorLocation, 0.0f, greenValue, 0.0f, 1.0f);
    /* we set the uniform value using glUniform4f
    4f means that it expects 4 floats
    few of possible postfixes:
        f: the function expects a float as its value.
        i: the function expects an int as its value.
        ui: the function expects an unsigned int as its value.
        3f: the function expects 3 floats as its value.
        fv: the function expects a float vector/array as its value.
    */
  }
}

void doDrawArrays(const unsigned int shaderProgram,
                  const unsigned int vertexArrayObject,
                  const GLenum drawArrayMode, const int firstIndex,
                  const unsigned int numberOfIndicesToBeRendered) {
  // use shader program to render an object
  glUseProgram(shaderProgram);
  updateUniformColor(shaderProgram, "ourColor");
  glBindVertexArray(vertexArrayObject);
  // From left:
  // primitive type we want to draw
  // starting index of vertex array
  // how many vertices we want to draw
  glDrawArrays(drawArrayMode, firstIndex, numberOfIndicesToBeRendered);
}

#endif  // #ifndef DRAW_CPP