OpenGL 材质实现
1.简介
在现实世界里，每个物体会对光产生不同的反应。比如，钢制物体看起来通常会比陶土花瓶更闪闪发光，一个木头箱子也不会与一个钢制箱子反射同样程度的光。有些物体反射光的时候不会有太多的散射，因而产生较小的高光点，而有些物体则会散射很多，产生一个有着更大半径的高光点。如果我们想要在OpenGL中模拟多种类型的物体，我们必须针对每种表面定义不同的材质(Material)属性。
当描述一个表面时，我们可以分别为三个光照分量定义一个材质颜色(Material Color)：
- 环境光照(Ambient Lighting)
- 漫反射光照(Diffuse Lighting)
- 镜面光照(Specular Lighting)
通过为每个分量指定一个颜色，我们就能够对表面的颜色输出有细粒度的控制了。
#version 330 core
struct Material {
vec3 ambient;
vec3 diffuse;
vec3 specular;
float shininess;
};
uniform Material material;- ambient材质向量定义了在环境光照下这个表面反射的是什么颜色，通常与表面的颜色相同。
- diffuse材质向量定义了在漫反射光照下表面的颜色。漫反射颜色（和环境光照一样）也被设置为我们期望的物体颜色。
- specular材质向量设置的是表面上镜面高光的颜色（或者甚至可能反映一个特定表面的颜色）。
- shininess影响镜面高光的散射/半径。
下图展示了几组现实世界的材质参数值对我们的立方体的影响：
2.设置材质
我们在片段着色器中创建了一个材质结构体的uniform，我们希望修改一下光照的计算来遵从新的材质属性。由于所有材质变量都储存在一个结构体中，我们可以从uniform变量material中访问它们：
void main()
{
// 环境光
vec3 ambient = lightColor * material.ambient;
// 漫反射
vec3 norm = normalize(Normal);
vec3 lightDir = normalize(lightPos - FragPos);
float diff = max(dot(norm, lightDir), 0.0);
vec3 diffuse = lightColor * (diff * material.diffuse);
// 镜面光
vec3 viewDir = normalize(viewPos - FragPos);
vec3 reflectDir = reflect(-lightDir, norm);
float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);
vec3 specular = lightColor * (spec * material.specular);
vec3 result = ambient + diffuse + specular;
FragColor = vec4(result, 1.0);
}我们现在可以通过设置适当的uniform来设置应用中物体的材质了。
m_program->setUniformValue("material.ambient", 1.0f, 0.5f, 0.31f);
m_program->setUniformValue("material.diffuse", 1.0f, 0.5f, 0.31f);
m_program->setUniformValue("material.specular", 0.5f, 0.5f, 0.5f);
m_program->setUniformValue("material.shininess", 32.0f);
3.示例
源码：
#version 330 core
struct Material {
vec3 ambient;
vec3 diffuse;
vec3 specular;
float shininess;
};
uniform Material material;
out vec4 color;
uniform vec3 lightPos;
uniform vec3 viewPos;
uniform vec3 lightColor;
in vec3 outNormal;
in vec3 FragPos;
void main()
{
// 环境光
vec3 ambient = lightColor * material.ambient;
// 漫反射
vec3 norm = normalize(outNormal);
vec3 lightDir = normalize(lightPos - FragPos);
float diff = max(dot(norm, lightDir), 0.0);
vec3 diffuse = lightColor * (diff * material.diffuse);
// 镜面光
vec3 viewDir = normalize(viewPos - FragPos);
vec3 reflectDir = reflect(-lightDir, norm);
float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);
vec3 specular = lightColor * (spec * material.specular);
vec3 result = ambient + diffuse + specular;
color = vec4(result, 1.0);
};
#ifndef MYOPENGLWIDGET_H
#define MYOPENGLWIDGET_H
#include
#include
#include
#include
#include
#include
#include
class MyOpenGLWidget : public QOpenGLWidget,public QOpenGLFunctions_3_3_Core
{
public:
MyOpenGLWidget(QWidget *parent = nullptr);
protected:
virtual void initializeGL();
virtual void paintGL();
virtual void resizeGL(int w, int h);
void keyPressEvent(QKeyEvent *event);
void mouseMoveEvent(QMouseEvent *event);
void wheelEvent(QWheelEvent *event);
private:
QOpenGLShaderProgram *m_program;
QOpenGLShaderProgram *m_lightProgram;
QVector3D cameraPos;
QVector3D cameraTarget;
QVector3D cameraDirection;
QVector3D up;
QVector3D cameraRight;
QVector3D cameraUp;
QVector3D cameraFront;
float cameraSpeed;
};
#endif // MYOPENGLWIDGET_H
#include "myopenglwidget.h"
#include
#include
#include
#include
#include
float vertices[] = {
//位置 //法向量
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
-0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, -1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, 0.5f, -1.0f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f,
0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f
};
GLuint indices[] = {
0, 1, 3,
1, 2, 3
};
GLuint VBO,VAO,EBO,lightVAO;
GLuint shaderProgram;
QVector3D lightPos(1.2f,1.0f,2.0f);
QVector3D lightColor(1.0f,1.0f,1.0f);
QVector3D objectColor(1.0f,0.5f,0.31f);
QTimer *timer;
QTime gtime;
float fov = 45.0f;
MyOpenGLWidget::MyOpenGLWidget(QWidget *parent)
: QOpenGLWidget(parent)
{
cameraPos = QVector3D( 0.0f, 0.0f, 5.0f);//摄像机位置
cameraTarget = QVector3D( 0.0f, 0.0f, 0.0f);//摄像机看到的位置
cameraDirection = QVector3D(cameraPos - cameraTarget);//摄像机的方向
cameraDirection.normalize();
up = QVector3D(0.0f, 1.0f, 0.0f);
cameraRight = QVector3D::crossProduct(up,cameraDirection);//两个向量叉乘的结果会同时垂直于两向量，因此我们会得到指向x轴正方向的那个向量
cameraRight.normalize();
cameraUp = QVector3D::crossProduct(cameraDirection,cameraRight);
cameraFront = QVector3D( 0.0f, 0.0f, -1.0f);
timer = new QTimer();
timer->start(50);
gtime.start();
connect(timer,&QTimer::timeout,[=]{
update();
});
setFocusPolicy(Qt::StrongFocus);
//setMouseTracking(true);
}
void MyOpenGLWidget::initializeGL()
{
initializeOpenGLFunctions();
m_program = new QOpenGLShaderProgram();
m_program->addShaderFromSourceFile(QOpenGLShader::Vertex,":/shapes.vert");
m_program->addShaderFromSourceFile(QOpenGLShader::Fragment,":/shapes.frag");
m_program->link();
qDebug()<log();
m_lightProgram = new QOpenGLShaderProgram();
m_lightProgram->addShaderFromSourceFile(QOpenGLShader::Vertex,":/light.vert");
m_lightProgram->addShaderFromSourceFile(QOpenGLShader::Fragment,":/light.frag");
m_lightProgram->link();
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
glBindVertexArray(VAO);//绑定VAO
glBindBuffer(GL_ARRAY_BUFFER, VBO);//顶点缓冲对象的缓冲类型是GL_ARRAY_BUFFER
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);//把顶点数据复制到缓冲的内存中GL_STATIC_DRAW ：数据不会或几乎不会改变。
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)(3*sizeof(GLfloat)));
glEnableVertexAttribArray(0);
glGenBuffers(1, &EBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
glGenVertexArrays(1, &lightVAO);
glBindVertexArray(lightVAO);//绑定VAO
glBindBuffer(GL_ARRAY_BUFFER, VBO);//顶点缓冲对象的缓冲类型是GL_ARRAY_BUFFER
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);//把顶点数据复制到缓冲的内存中GL_STATIC_DRAW ：数据不会或几乎不会改变。
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)0);
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
m_program->bind();
m_program->setUniformValue("lightPos",lightPos);
m_program->setUniformValue("viewPos",cameraPos);
m_program->setUniformValue("lightColor",lightColor);
m_program->setUniformValue("material.ambient", 1.0f, 0.5f, 0.31f);
m_program->setUniformValue("material.diffuse", 1.0f, 0.5f, 0.31f);
m_program->setUniformValue("material.specular", 0.5f, 0.5f, 0.5f);
m_program->setUniformValue("material.shininess", 32.0f);
m_lightProgram->bind();
m_lightProgram->setUniformValue("lightColor",lightColor);
glBindVertexArray(0);//解绑VAO
}
void MyOpenGLWidget::paintGL()
{
glClearColor(0.2f,0.3f,0.3f,1.0f);
glEnable(GL_DEPTH_TEST);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
QMatrix4x4 model;
QMatrix4x4 view;
float time = gtime.elapsed()/50.0;
QMatrix4x4 projection;
projection.perspective(fov,(float)( width())/(height()),0.1,100);
view.lookAt(cameraPos,cameraPos + cameraFront,up);
m_program->bind();
m_program->setUniformValue("projection",projection);
m_program->setUniformValue("view",view);
glBindVertexArray(VAO);//绑定VAO
model.rotate(time,1.0f,5.0f,0.5f);
m_program->setUniformValue("model",model);
glDrawArrays(GL_TRIANGLES,0,36);
m_lightProgram->bind();
m_lightProgram->setUniformValue("projection",projection);
m_lightProgram->setUniformValue("view",view);
model.setToIdentity();
model.translate(lightPos);
model.rotate(1.0f,1.0f,5.0f,0.5f);
model.scale(0.2);
m_lightProgram->setUniformValue("model",model);
glBindVertexArray(lightVAO);//绑定VAO
glDrawArrays(GL_TRIANGLES,0,36);
}
void MyOpenGLWidget::resizeGL(int w, int h)
{
}
void MyOpenGLWidget::keyPressEvent(QKeyEvent *event)
{
qDebug()<key();
cameraSpeed = 2.5 * 100 / 1000.0;
switch (event->key()) {
case Qt::Key_W:{
cameraPos += cameraSpeed * cameraFront;
}
break;
case Qt::Key_S:{
cameraPos -= cameraSpeed * cameraFront;
}
break;
case Qt::Key_A:{
cameraPos -= cameraSpeed * cameraRight;
}
break;
case Qt::Key_D:{
cameraPos += cameraSpeed * cameraRight;
}
break;
default:
break;
}
update();
}
float PI = 3.1415926;
QPoint deltaPos;
void MyOpenGLWidget::mouseMoveEvent(QMouseEvent *event)
{
// static float yaw = -90;
// static float pitch = 0;
// static QPoint lastPos(width()/2,height()/2);
// auto currentPos = event->pos();
// deltaPos = currentPos-lastPos;
// lastPos=currentPos;
// float sensitivity = 0.1f;
// deltaPos *= sensitivity;
// yaw += deltaPos.x();
// pitch -= deltaPos.y();
// if(pitch > 89.0f) pitch = 89.0f;
// if(pitch < -89.0f) pitch = -89.0f;
// cameraFront.setX(cos(yaw*PI/180.0) * cos(pitch *PI/180));
// cameraFront.setY(sin(pitch*PI/180));
// cameraFront.setZ(sin(yaw*PI/180) * cos(pitch *PI/180));
// cameraFront.normalize();
// update();
}
void MyOpenGLWidget::wheelEvent(QWheelEvent *event)
{
if(fov >= 1.0f && fov <= 75.0f)
fov -= event->angleDelta().y()/120;
if(fov <= 1.0f)
fov = 1.0f;
if(fov >= 75.0f)
fov = 75.0f;
update();
}
这个物体太亮了。物体过亮的原因是环境光、漫反射和镜面光这三个颜色对任何一个光源都全力反射。
我们可以用同样的方式影响光源的漫反射和镜面光强度。我们希望为光照属性创建类似材质结构体的东西：
struct Light {
vec3 position;
vec3 ambient;
vec3 diffuse;
vec3 specular;
};
uniform Light light;和材质uniform一样，我们需要更新片段着色器：
vec3 ambient = light.ambient * material.ambient;
vec3 diffuse = light.diffuse * (diff * material.diffuse);
vec3 specular = light.specular * (spec * material.specular);我们接下来在应用中设置光照强度：
m_program->setUniformValue("light.ambient", QVector3D(0.2f, 0.2f, 0.2f));
m_program->setUniformValue("light.diffuse", QVector3D(0.5f, 0.5f, 0.5f));
m_program->setUniformValue("light.specular", QVector3D(1.0,1.0,1.0));结果如下：
4.不同颜色的光
设置一个随时间改变的光的颜色。
lightColor.setX(sin(time/100 * 2.0f));
lightColor.setY(sin(time/100 * 0.7f));
lightColor.setZ(sin(time/100 * 1.3f));
QVector3D diffuseColor = lightColor * QVector3D(0.5f,0.5f,0.5f); // 降低影响
QVector3D ambientColor = diffuseColor * QVector3D(0.2f,0.2f,0.2f); // 很低的影响
m_program->setUniformValue("material.ambient", ambientColor);
m_program->setUniformValue("material.diffuse", diffuseColor);
5.完整源码
https://download.csdn.net/download/wzz953200463/87893740
https://download.csdn.net/download/wzz953200463/87893740