Qt OpenGL 光照实现

        Qt 中使用 OpenGL 实现光照效果主要基于 OpenGL 的光照模型和着色器编程。以下是 Qt OpenGL 光照实现的核心原理：

一. 光照模型基础

OpenGL 使用 Phong 光照模型，包含三个主要光照分量：

• 环境光(Ambient)：场景中的基础光照，没有方向性

• 漫反射光(Diffuse)：与表面法线和光线方向相关的散射光

• 镜面光(Specular)：在特定角度可见的高光反射

二. Qt 中的实现方式

2.1 传统固定管线方式 (已过时但简单)

cpp

// 启用光照
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0); // 启用0号光源

// 设置光源属性
GLfloat lightPosition[] = {1.0f, 1.0f, 1.0f, 1.0f};
GLfloat lightAmbient[] = {0.2f, 0.2f, 0.2f, 1.0f};
GLfloat lightDiffuse[] = {0.8f, 0.8f, 0.8f, 1.0f};
GLfloat lightSpecular[] = {1.0f, 1.0f, 1.0f, 1.0f};

glLightfv(GL_LIGHT0, GL_POSITION, lightPosition);
glLightfv(GL_LIGHT0, GL_AMBIENT, lightAmbient);
glLightfv(GL_LIGHT0, GL_DIFFUSE, lightDiffuse);
glLightfv(GL_LIGHT0, GL_SPECULAR, lightSpecular);

// 设置材质属性
GLfloat materialAmbient[] = {0.7f, 0.7f, 0.7f, 1.0f};
GLfloat materialDiffuse[] = {0.8f, 0.8f, 0.8f, 1.0f};
GLfloat materialSpecular[] = {1.0f, 1.0f, 1.0f, 1.0f};
GLfloat materialShininess = 100.0f;

glMaterialfv(GL_FRONT, GL_AMBIENT, materialAmbient);
glMaterialfv(GL_FRONT, GL_DIFFUSE, materialDiffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR, materialSpecular);
glMaterialf(GL_FRONT, GL_SHININESS, materialShininess);

2.2 现代可编程管线方式 (推荐)

使用着色器实现光照效果：

顶点着色器示例

glsl

#version 330 core

layout(location = 0) in vec3 position;
layout(location = 1) in vec3 normal;

out vec3 FragPos;
out vec3 Normal;

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

void main()
{
    FragPos = vec3(model * vec4(position, 1.0));
    Normal = mat3(transpose(inverse(model))) * normal;
    gl_Position = projection * view * vec4(FragPos, 1.0);
}

片段着色器示例 (Phong光照)

glsl

#version 330 core

in vec3 FragPos;
in vec3 Normal;

out vec4 FragColor;

uniform vec3 lightPos;
uniform vec3 viewPos;
uniform vec3 lightColor;
uniform vec3 objectColor;

void main()
{
    // 环境光
    float ambientStrength = 0.1;
    vec3 ambient = ambientStrength * lightColor;
    
    // 漫反射
    vec3 norm = normalize(Normal);
    vec3 lightDir = normalize(lightPos - FragPos);
    float diff = max(dot(norm, lightDir), 0.0);
    vec3 diffuse = diff * lightColor;
    
    // 镜面光
    float specularStrength = 0.5;
    vec3 viewDir = normalize(viewPos - FragPos);
    vec3 reflectDir = reflect(-lightDir, norm);
    float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32);
    vec3 specular = specularStrength * spec * lightColor;
    
    vec3 result = (ambient + diffuse + specular) * objectColor;
    FragColor = vec4(result, 1.0);
}

三. Qt 中的实现步骤

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