基于Qt的OpenGL编程（3.x以上GLSL可编程管线版）---(九)颜色

这章内容作为OpenGL的光照体系的一个起点，简单说明如何在OpenGL中应用颜色

（Vries的原教程地址如下，https://learnopengl-cn.github.io/02%20Lighting/01%20Colors/ 关于OpenGL函数的详细解析及OpenGL关于颜色这里的知识点详情描述请看这个教程，本篇旨在对Vires基于visual studio的编程思想做Qt平台的移植，重在记录自身学习之用）

实现Vries的第一个简单的颜色应用

项目组织如下，在我上一节，已上传了这个框架代码的百度云连接：

 https://pan.baidu.com/s/196FAnQylehc9XHOUR8MLIg

因为有了框架，所以仅修改cube.h, cube.cpp, oglmanager.cpp与两个shader文件

cube.vert

#version 330 core
layout (location = 0) in vec3 aPos;

uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

void main(){
  gl_Position = projection * view * model * vec4(aPos, 1.0f);
}

cube.frag

#version 330 core
out vec4 FragColor;

uniform vec3 objectColor;
uniform vec3 lightColor;

void main()
{
  FragColor = vec4(objectColor * lightColor, 1.0f);
}

light.vert

#version 330 core
layout (location = 0) in vec3 aPos;

uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

void main(){
  gl_Position = projection * view * model * vec4(aPos, 1.0f);
}

light.frag

#version 330 core
out vec4 FragColor;

void main()
{
  FragColor = vec4(1.0f);
}

cube.h

#ifndef CUBE_H
#define CUBE_H

#include <QOpenGLFunctions_3_3_Core>

class Cube
{
public:
  Cube();
  ~Cube();
  void init();
  void drawLight();
  void drawCube();
private:
  QOpenGLFunctions_3_3_Core *core;
  GLuint VBO, cubeVAO, lightVAO;
};

#endif // CUBE_H

cube.cpp

#include "cube.h"
#include "resourcemanager.h"

Cube::Cube(){

}

Cube::~Cube(){
  core->glDeleteVertexArrays(1, &cubeVAO);
  core->glDeleteVertexArrays(1, &lightVAO);
}

void Cube::init(){
  core = QOpenGLContext::currentContext()->versionFunctions<QOpenGLFunctions_3_3_Core>();
  GLfloat vertices[] = {
    -0.5f, -0.5f, -0.5f,
    0.5f, -0.5f, -0.5f,
    0.5f,  0.5f, -0.5f,
    0.5f,  0.5f, -0.5f,
    -0.5f,  0.5f, -0.5f,
    -0.5f, -0.5f, -0.5f,

    -0.5f, -0.5f,  0.5f,
    0.5f, -0.5f,  0.5f,
    0.5f,  0.5f,  0.5f,
    0.5f,  0.5f,  0.5f,
    -0.5f,  0.5f,  0.5f,
    -0.5f, -0.5f,  0.5f,

    -0.5f,  0.5f,  0.5f,
    -0.5f,  0.5f, -0.5f,
    -0.5f, -0.5f, -0.5f,
    -0.5f, -0.5f, -0.5f,
    -0.5f, -0.5f,  0.5f,
    -0.5f,  0.5f,  0.5f,

    0.5f,  0.5f,  0.5f,
    0.5f,  0.5f, -0.5f,
    0.5f, -0.5f, -0.5f,
    0.5f, -0.5f, -0.5f,
    0.5f, -0.5f,  0.5f,
    0.5f,  0.5f,  0.5f,

    -0.5f, -0.5f, -0.5f,
    0.5f, -0.5f, -0.5f,
    0.5f, -0.5f,  0.5f,
    0.5f, -0.5f,  0.5f,
    -0.5f, -0.5f,  0.5f,
    -0.5f, -0.5f, -0.5f,

    -0.5f,  0.5f, -0.5f,
    0.5f,  0.5f, -0.5f,
    0.5f,  0.5f,  0.5f,
    0.5f,  0.5f,  0.5f,
    -0.5f,  0.5f,  0.5f,
    -0.5f,  0.5f, -0.5f
  };

  core->glGenVertexArrays(1, &cubeVAO);//两个参数，第一个为需要创建的缓存数量。第二个为用于存储单一ID或多个ID的GLuint变量或数组的地址
  core->glGenVertexArrays(1, &lightVAO);
  core->glGenBuffers(1, &VBO);

  core->glBindBuffer(GL_ARRAY_BUFFER, VBO);
  core->glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

  core->glBindVertexArray(cubeVAO);
    core->glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
    core->glEnableVertexAttribArray(0);
  core->glBindVertexArray(0);

  core->glBindVertexArray(lightVAO);
    core->glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
    core->glEnableVertexAttribArray(0);
  core->glBindVertexArray(0);

  core->glDeleteBuffers(1, &VBO);
}

void Cube::drawCube(){
  core->glBindVertexArray(cubeVAO);
  core->glDrawArrays(GL_TRIANGLES, 0, 36);
}

void Cube::drawLight(){
    core->glBindVertexArray(lightVAO);
    core->glDrawArrays(GL_TRIANGLES, 0, 36);
}

oglmanager.cpp

#include "oglmanager.h"
#include <QKeyEvent>
#include <QDebug>
#include "resourcemanager.h"
#include "cube.h"

const QVector3D CAMERA_POSITION(0.0f, 0.0f, 3.0f);
const QVector3D LIGHT_POSITION(1.0f, 0.8f, 0.8f);

Cube *cube;

OGLManager::OGLManager(GLuint w, GLuint h){
  this->width = w;
  this->height = h;
  for(GLuint i = 0; i != 1024; ++i)
    keys[i] = GL_FALSE;

}

OGLManager::~OGLManager(){
  delete this->camera;
  ResourceManager::clear();
}

void OGLManager::init(){
  cube = new Cube();

  this->camera = new Camera(CAMERA_POSITION);
  cube->init();
  core = QOpenGLContext::currentContext()->versionFunctions<QOpenGLFunctions_3_3_Core>();

  ResourceManager::loadShader("cube", ":/shaders/res/shaders/cube.vert", ":/shaders/res/shaders/cube.frag");
  ResourceManager::loadShader("light", ":/shaders/res/shaders/light.vert", ":/shaders/res/shaders/light.frag");


  ResourceManager::getShader("cube").use().setVector3f("objectColor", QVector3D(1.0f, 0.5f, 0.31f));
  ResourceManager::getShader("cube").use().setVector3f("lightColor", QVector3D(1.0f, 1.0f, 1.0f));

  //开启状态
  core->glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
  core->glEnable(GL_DEPTH_TEST);
}

void OGLManager::processInput(GLfloat dt){
  if (keys[Qt::Key_W])
    camera->processKeyboard(FORWARD, dt);
  if (keys[Qt::Key_S])
    camera->processKeyboard(BACKWARD, dt);
  if (keys[Qt::Key_A])
    camera->processKeyboard(LEFT, dt);
  if (keys[Qt::Key_D])
    camera->processKeyboard(RIGHT, dt);
  if (keys[Qt::Key_E])
    camera->processKeyboard(UP, dt);
  if (keys[Qt::Key_Q])
    camera->processKeyboard(DOWN, dt);
}


void OGLManager::update(GLfloat dt){
  QMatrix4x4 projection, model;
  projection.perspective(camera->zoom, (GLfloat)width/(GLfloat)height, 0.1f, 200.f);

  ResourceManager::getShader("cube").use().setMatrix4f("projection", projection);
  ResourceManager::getShader("cube").use().setMatrix4f("view", camera->getViewMatrix());
  ResourceManager::getShader("cube").use().setMatrix4f("model", model);

  model.translate(LIGHT_POSITION);
  model.scale(0.2f);
  ResourceManager::getShader("light").use().setMatrix4f("projection", projection);
  ResourceManager::getShader("light").use().setMatrix4f("view", camera->getViewMatrix());
  ResourceManager::getShader("light").use().setMatrix4f("model", model);
}

void OGLManager::resize(GLuint w, GLuint h){
  core->glViewport(0, 0, w, h);
}

void OGLManager::draw(GLfloat dt)
{
  core->glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  ResourceManager::getShader("cube").use();
  cube->drawCube();

  ResourceManager::getShader("light").use();
  cube->drawLight();
}