基于Qt的OpenGL编程（3.x以上GLSL可编程管线版）---(十三)投光物

其他 2018-08-19 16:43:56 阅读次数: 0

（Vries的原教程地址如下，https://learnopengl-cn.github.io/02%20Lighting/05%20Light%20casters/ 关于OpenGL函数的详细解析及OpenGL关于平行光，点光源，手电筒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）


Qt开发平台：5.8.0

编译器：Desktop Qt 5.8.0 MSVC2015_64bit


一.平行光

效果如图所示，去除固定光源，改为平行光。

修改起来还是很容易的，简单修改箱子的片段着色器即可。感觉效果没有固定光源明显。。。


项目管理如下：


cube.frag

#version 330 core
struct Material{
  sampler2D diffuse;
  sampler2D specular;
  float shininess;
};

struct Light{
		//vec3 position;
  vec3 direction;//定向光源

  vec3 ambient;
  vec3 diffuse;
  vec3 specular;
};

out vec4 FragColor;
in vec2 TexCoords;

uniform Material material;
uniform Light light;

uniform vec3 viewPos;

in vec3 Normal;
in vec3 FragPos;

void main()
{
		//ambient
		vec3 ambient = light.ambient * vec3(texture2D(material.diffuse, TexCoords));

		//diffuse
		vec3 norm = normalize(Normal);
		//vec3 lightDir = normalize(light.position - FragPos);
		vec3 lightDir = normalize(-light.direction);
		float diff = max(dot(norm, lightDir), 0.0f);
		vec3 diffuse = light.diffuse * (diff * vec3(texture2D(material.diffuse, TexCoords)));

		//specular
		vec3 viewDir = normalize(viewPos - FragPos);
		vec3 reflectDir = reflect(-lightDir, norm);
		float spec = pow(max(dot(viewDir, reflectDir), 0.0f), material.shininess);
		vec3 specular = light.specular * (spec * vec3(texture2D(material.specular, TexCoords)));

		//all
		vec3 result =  ambient + diffuse + specular;
		FragColor = vec4(result, 1.0f);

}

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().setInteger("material.diffuse", 0);
  ResourceManager::getShader("cube").use().setInteger("material.specular", 1);
  ResourceManager::getShader("cube").use().setFloat("material.shininess", 64.0f);

  ResourceManager::getShader("cube").use().setVector3f("light.ambient", QVector3D(0.2f, 0.2f, 0.2f));
  ResourceManager::getShader("cube").use().setVector3f("light.diffuse", QVector3D(0.5f, 0.5f, 0.5f));
  ResourceManager::getShader("cube").use().setVector3f("light.specular", QVector3D(1.0f, 1.0f, 1.0f));
  //aResourceManager::getShader("cube").use().setVector3f("light.position", LIGHT_POSITION);
  ResourceManager::getShader("cube").use().setVector3f("light.direction", QVector3D(-0.2f, -1.0f, -0.3f));

  QMatrix4x4 model;
  ResourceManager::getShader("cube").use().setMatrix4f("model", model);
  model.translate(LIGHT_POSITION);
  model.scale(0.2f);
  ResourceManager::getShader("light").use().setMatrix4f("model", model);


  //开启状态
  core->glClearColor(0.1f, 0.1f, 0.1f, 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().setVector3f("viewPos", camera->position);

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

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

QVector3D cubePositions[] = {
    QVector3D( 0.0f,  0.0f,  0.0f),
    QVector3D( 2.0f,  5.0f, -15.0f),
    QVector3D(-1.5f, -2.2f, -2.5f),
    QVector3D(-3.8f, -2.0f, -12.3f),
    QVector3D( 2.4f, -0.4f, -3.5f),
    QVector3D(-1.7f,  3.0f, -7.5f),
    QVector3D( 1.3f, -2.0f, -2.5f),
    QVector3D( 1.5f,  2.0f, -2.5f),
    QVector3D( 1.5f,  0.2f, -1.5f),
    QVector3D(-1.3f,  1.0f, -1.5f)
};

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

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

  for (unsigned int i = 0; i < 10; i++){
    QMatrix4x4 model;
    model.translate(cubePositions[i]);
    GLfloat angle = 20.0f * i;
    model.rotate(angle, QVector3D(1.0f, 0.3f, 0.5f));
    ResourceManager::getShader("cube").use().setMatrix4f("model", model);

    cube->drawCube();
  }
}

二.有光照衰减的点光源


在固定点光源的情形下，进行光照衰减，emmm，如上图所示，挺有意思的效果，挺真实。

使用一下衰减公式：


衰减效果如下图，近距离衰减快，远距离衰减慢。


修改cube.frag与oglmanager.cpp即可

cube.frag

#version 330 core
struct Material{
  sampler2D diffuse;
  sampler2D specular;
  float shininess;
};


struct Light{
  vec3 position;//固定点光源
  //vec3 direction;//定向光源

  vec3 ambient;
  vec3 diffuse;
  vec3 specular;

  //光照衰减用三变量
  float constant;
  float linear;
  float quadratic;
};

out vec4 FragColor;
in vec2 TexCoords;

uniform Material material;
uniform Light light;
uniform vec3 viewPos;

in vec3 Normal;
in vec3 FragPos;


void main()
{
  //ambient
  vec3 ambient = light.ambient * vec3(texture2D(material.diffuse, TexCoords));

  //diffuse
  vec3 norm = normalize(Normal);
  vec3 lightDir = normalize(light.position - FragPos);//固定点光源
  //vec3 lightDir = normalize(-light.direction);//定向平行光源
  float diff = max(dot(norm, lightDir), 0.0f);
  vec3 diffuse = light.diffuse * (diff * vec3(texture2D(material.diffuse, TexCoords)));

  //specular
  vec3 viewDir = normalize(viewPos - FragPos);
  vec3 reflectDir = reflect(-lightDir, norm);
  float spec = pow(max(dot(viewDir, reflectDir), 0.0f), material.shininess);
  vec3 specular = light.specular * (spec * vec3(texture2D(material.specular, TexCoords)));

  //光照衰减公式
  float distance = length(light.position - FragPos);
  float attenuation = 1.0 / (light.constant + light.linear * distance + light.quadratic * (distance * distance));

  //all
  vec3 result =  (ambient + diffuse + specular) * attenuation;
  FragColor = vec4(result, 1.0f);
}

oglmanager.cpp

...........................  
ResourceManager::getShader("cube").use().setVector3f("light.position", LIGHT_POSITION);//固定点
  //ResourceManager::getShader("cube").use().setVector3f("light.direction", QVector3D(-0.2f, -1.0f, -0.3f));//平行光源
  ResourceManager::getShader("cube").use().setFloat("light.constant", 1.0f);
  ResourceManager::getShader("cube").use().setFloat("light.linear", 0.09f);
  ResourceManager::getShader("cube").use().setFloat("light.quadratic", 0.032f);
.......................

二.手电筒


很有趣的效果，实现起来也很简单，原理如下，简单修改cube.frag


cube.frag

#version 330 core
struct Material{
  sampler2D diffuse;
  sampler2D specular;
  float shininess;
};

struct Light{
  vec3 position;//固定点光源
  vec3 direction;//光源方向

  vec3 ambient;
  vec3 diffuse;
  vec3 specular;

  float cutOff;

//		//光照衰减用三变量
//		float constant;
//		float linear;
//		float quadratic;
};

out vec4 FragColor;
in vec2 TexCoords;

uniform Material material;
uniform Light light;

uniform vec3 viewPos;

in vec3 Normal;
in vec3 FragPos;

void main()
{
  //ambient
  vec3 ambient = light.ambient * vec3(texture2D(material.diffuse, TexCoords));

  //diffuse
  vec3 norm = normalize(Normal);
  vec3 lightDir = normalize(light.position - FragPos);//固定点光源
  //vec3 lightDir = normalize(-light.direction);//定向平行光源
  float diff = max(dot(norm, lightDir), 0.0f);
  vec3 diffuse = light.diffuse * (diff * vec3(texture2D(material.diffuse, TexCoords)));

  //specular
  vec3 viewDir = normalize(viewPos - FragPos);
  vec3 reflectDir = reflect(-lightDir, norm);
  float spec = pow(max(dot(viewDir, reflectDir), 0.0f), material.shininess);
  vec3 specular = light.specular * (spec * vec3(texture2D(material.specular, TexCoords)));

//		//光照衰减公式
//		float distance = length(light.position - FragPos);
//		float attenuation = 1.0 / (light.constant + light.linear * distance + light.quadratic * (distance * distance));

		//all
//		vec3 result =  (ambient + diffuse + specular) * attenuation;
  vec3 result =  ambient + diffuse + specular;

  //手电筒
  float theta = dot(lightDir, normalize(-light.direction));
  if(theta > light.cutOff)
    FragColor = vec4(result, 1.0f);
  else
    FragColor = vec4(ambient, 1.0f);
}

oglmanager.cpp

  ResourceManager::getShader("cube").use().setFloat("light.cutOff", cos(12.5f/180.f * 3.14));
  ResourceManager::getShader("cube").use().setVector3f("light.position", camera->position);
  ResourceManager::getShader("cube").use().setVector3f("light.direction", camera->front);

  2.1平滑/软化边缘

  

在边缘加一个衰减，显得更现实一些。实现起来也很简单，在内圆锥外 再加一个外圆锥，

内圆锥内，衰减*1.0f，外圆锥外，衰减*1.0f，两圆锥之内，计算一个0.0到1.0之间的强度值。

修改cube.frag

#version 330 core
struct Material{
  sampler2D diffuse;
  sampler2D specular;
  float shininess;
};

struct Light{
  vec3 direction;//光源方向
  vec3 position;
  vec3 ambient;
  vec3 diffuse;
  vec3 specular;

  float cutOff;
  float outerCutOff;
};

out vec4 FragColor;
in vec2 TexCoords;

uniform Material material;
uniform Light light;

uniform vec3 viewPos;

in vec3 Normal;
in vec3 FragPos;

void main()
{
  //ambient
  vec3 ambient = light.ambient * vec3(texture2D(material.diffuse, TexCoords));

  //diffuse
  vec3 norm = normalize(Normal);
  vec3 lightDir = normalize(light.position - FragPos);//固定点光源
  //vec3 lightDir = normalize(-light.direction);//定向平行光源
  float diff = max(dot(norm, lightDir), 0.0f);
  vec3 diffuse = light.diffuse * (diff * vec3(texture2D(material.diffuse, TexCoords)));

  //specular
  vec3 viewDir = normalize(viewPos - FragPos);
  vec3 reflectDir = reflect(-lightDir, norm);
  float spec = pow(max(dot(viewDir, reflectDir), 0.0f), material.shininess);
  vec3 specular = light.specular * (spec * vec3(texture2D(material.specular, TexCoords)));

  //all
  vec3 result =  ambient + diffuse + specular;

  //手电筒
  float theta = dot(lightDir, normalize(-light.direction));
  float epsilon = light.cutOff - light.outerCutOff;
  float intensity = clamp((theta - light.outerCutOff)/epsilon, 0.0f, 1.0f);
  FragColor = vec4(result * intensity, 1.0f);
}

oglmanager.cpp

  ResourceManager::getShader("cube").use().setFloat("light.outerCutOff", cos(17.5f/180.f * 3.14));


2.2路灯效果

将手电筒改成路灯也很简单，只用修改oglmanager.cpp里的参数设置，修改cube.frag中的 light.direction和light.position参数

oglmanager.cpp

void init(){
...... 
  ResourceManager::getShader("cube").use().setVector3f("light.position", LIGHT_POSITION);
  ResourceManager::getShader("cube").use().setVector3f("light.direction", QVector3D(0.0f, -1.0f, 0.0f));
....
}

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