Opengl实验报告及源代码实验六 颜色与光照

南昌大学实验报告

学生姓名：学号：专业班级：

实验类型：□验证□综合□设计□创新实验日期：2018.11 实验成绩：

一、实验名称

实验六颜色与光照

二、实验内容

1.指定几何模型的绘制颜色，使用平滑着色模式用多种不同的颜色绘制多边形；

2.通过定义光源、材质和光照模型属性渲染物体的光照效果；

3.创建一个3D虚拟场景，利用定向光、点光源和聚光灯等不同光源实现3D场景的光

照效果。

三、实验目的

1.了解RGBA颜色的实现原理，掌握利用Flat和Smooth着色模式来绘制不同颜色的物

体的方法；

2.掌握OpenGL光照模型，理解光源、材质和光照模型如何综合影响物体的光照效果。

3.掌握定向光、点光源和聚光灯的不同属性及三种光源光照效果的计算方法。

四、实验步骤

1.建立立方体几何模型。定义立方体顶点的位置坐标和纹理坐标，设置不同立方体在

世界坐标系中的位置：

// Set up vertex data (and buffer(s)) and attribute pointers

GLfloat vertices[] = {

// Positions // Normals // Texture Coords

-0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f,

0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f,

0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f,

0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f,

-0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 0.0f, 1.0f,

-0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f,

-0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f,

0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f,

0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f,

0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f,

-0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f,

-0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f, -0.5f, 0.5f, -0.5f, -1.0f, 0.0f, 0.0f, 1.0f, 1.0f, -0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f, -0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f, -0.5f, -0.5f, 0.5f, -1.0f, 0.0f, 0.0f, 0.0f, 0.0f, -0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f,

0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f,

0.5f, 0.5f, -0.5f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f,

0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f,

0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f,

0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f,

0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f,

-0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f, 0.0f, 1.0f,

0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f, 1.0f, 1.0f,

0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f,

0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f,

-0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f, 0.0f, 0.0f, -0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f, 0.0f, 1.0f,

-0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f,

0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f,

0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f,

0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f,

-0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, -0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f };

// Positions all containers

glm::vec3 cubePositions[] = {

glm::vec3(0.0f, 0.0f, 0.0f),

glm::vec3(2.0f, 5.0f, -15.0f),

glm::vec3(-1.5f, -2.2f, -2.5f),

glm::vec3(-3.8f, -2.0f, -12.3f),

glm::vec3(2.4f, -0.4f, -3.5f),

glm::vec3(-1.7f, 3.0f, -7.5f),

glm::vec3(1.3f, -2.0f, -2.5f),

glm::vec3(1.5f, 2.0f, -2.5f),

glm::vec3(1.5f, 0.2f, -1.5f),

glm::vec3(-1.3f, 1.0f, -1.5f)

};

2.加载立方体模型的顶点数据。建立VAO、VBO 对象变量，编写顶点数据加载函数，

组织并加装几何模型的数据：

GLuint VBO, containerVAO;

glGenVertexArrays(1, &containerVAO);

glGenBuffers(1, &VBO);

glBindBuffer(GL_ARRAY_BUFFER, VBO);

glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

glBindVertexArray(containerVAO);

glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)0);

glEnableVertexAttribArray(0);

glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));

glEnableVertexAttribArray(1);

glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(6 * sizeof(GLfloat)));

glEnableVertexAttribArray(2);

glBindVertexArray(0);

3.设置灯光的VAO，并绑定VBO：

GLuint lightVAO;

glGenVertexArrays(1, &lightVAO);

glBindVertexArray(lightVAO);

glBindBuffer(GL_ARRAY_BUFFER, VBO);

// Set the vertex attributes (only position data for the lamp))

glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)0);

glEnableVertexAttribArray(0);

glBindVertexArray(0);

4.创建纹理，加载图片，设置纹理单元：

GLuint diffuseMap, specularMap, emissionMap;

glGenTextures(1, &diffuseMap);

glGenTextures(1, &specularMap);

glGenTextures(1, &emissionMap);

int width, height;

unsigned char* image;

// Diffuse map

image = SOIL_load_image("wall.jpg", &width, &height, 0, SOIL_LOAD_RGB);

glBindTexture(GL_TEXTURE_2D, diffuseMap);

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);

glGenerateMipmap(GL_TEXTURE_2D);

SOIL_free_image_data(image);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST_MIPMAP_NEAREST);

// Specular map

image = SOIL_load_image("test_rect.png", &width, &height, 0, SOIL_LOAD_RGB);

glBindTexture(GL_TEXTURE_2D, specularMap);

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);

glGenerateMipmap(GL_TEXTURE_2D);

SOIL_free_image_data(image);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST_MIPMAP_NEAREST);

glBindTexture(GL_TEXTURE_2D, 0);

// Set texture units

https://www.360docs.net/doc/da454076.html,e();

glUniform1i(glGetUniformLocation(lightingShader.Program, "material.diffuse"), 0);

glUniform1i(glGetUniformLocation(lightingShader.Program, "material.specular"), 1);

5.编写灯光的顶点着色器和片段着色器：

#version 330 core

layout (location = 0) in vec3 position;

layout (location = 1) in vec3 normal;

layout (location = 2) in vec2 texCoords;

out vec3 Normal;

out vec3 FragPos;

out vec2 TexCoords;

uniform mat4 model;

uniform mat4 view;

uniform mat4 projection;

void main()

{

gl_Position = projection * view * model * vec4(position, 1.0f);

FragPos = vec3(model * vec4(position, 1.0f));

Normal = mat3(transpose(inverse(model))) * normal;

TexCoords = texCoords;

}

#version 330 core

struct Material {

sampler2D diffuse;

sampler2D specular;

float shininess;

};

struct Light {

vec3 position;

vec3 direction;

float cutOff;

float constant;

float linear;

float quadratic;

vec3 ambient;

vec3 diffuse;

vec3 specular;

};

in vec3 FragPos;

in vec3 Normal;

in vec2 TexCoords;

out vec4 color;

uniform vec3 viewPos;

uniform Material material;

uniform Light light;

void main()

{

vec3 lightDir = normalize(light.position - FragPos);

// Check if lighting is inside the spotlight cone

float theta = dot(lightDir, normalize(-light.direction));

if(theta > light.cutOff) // Remember that we're working with angles as cosines instead of degrees so a '>' is used.

{

// Ambient

vec3 ambient = light.ambient * vec3(texture(material.diffuse, TexCoords));

// Diffuse

vec3 norm = normalize(Normal);

float diff = max(dot(norm, lightDir), 0.0);

vec3 diffuse = light.diffuse * diff * vec3(texture(material.diffuse, TexCoords)); // Specular

vec3 viewDir = normalize(viewPos - FragPos);

vec3 reflectDir = reflect(-lightDir, norm);

float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);

vec3 specular = light.specular * spec * vec3(texture(material.specular, TexCoords)); // Attenuation

float distance = length(light.position - FragPos);

float attenuation = 1.0f / (light.constant + light.linear * distance + light.quadratic * (distance * distance));

// ambient *= attenuation; // Also remove attenuation from ambient, because if we move too far, the light in spotlight would then be darker than outside (since outside spotlight we have ambient lighting).

diffuse *= attenuation;

specular *= attenuation;

color = vec4(ambient + diffuse + specular, 1.0f);

}

else // else, use ambient light so scene isn't completely dark outside the spotlight.

color = vec4(light.ambient * vec3(texture(material.diffuse, TexCoords)), 1.0f);

}

6.用相应的着色器绘制对象，设定灯光和材料特性，并创建摄像机变换：

// Calculate deltatime of current frame

GLfloat currentFrame = glfwGetTime();

deltaTime = currentFrame - lastFrame;

lastFrame = currentFrame;

// Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functions

glfwPollEvents();

do_movement();

// Clear the colorbuffer

glClearColor(0.1f, 0.1f, 0.1f, 1.0f);

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

// Use cooresponding shader when setting uniforms/drawing objects 用相应的着色器绘制对象

https://www.360docs.net/doc/da454076.html,e();

GLint lightPosLoc = glGetUniformLocation(lightingShader.Program, "light.position");

GLint lightSpotdirLoc = glGetUniformLocation(lightingShader.Program, "light.direction");

GLint lightSpotCutOffLoc = glGetUniformLocation(lightingShader.Program, "light.cutOff");

GLint viewPosLoc = glGetUniformLocation(lightingShader.Program, "viewPos");

glUniform3f(lightPosLoc, camera.Position.x, camera.Position.y, camera.Position.z);

glUniform3f(lightSpotdirLoc, camera.Front.x, camera.Front.y, camera.Front.z);

glUniform1f(lightSpotCutOffLoc, glm::cos(glm::radians(12.5f)));

glUniform3f(viewPosLoc, camera.Position.x, camera.Position.y, camera.Position.z);

// Set lights properties

glUniform3f(glGetUniformLocation(lightingShader.Program, "light.ambient"), 0.1f,

0.1f, 0.1f);

glUniform3f(glGetUniformLocation(lightingShader.Program, "light.diffuse"), 0.8f,

0.8f, 0.8f);

glUniform3f(glGetUniformLocation(lightingShader.Program, "light.specular"), 1.0f,

1.0f, 1.0f);

glUniform1f(glGetUniformLocation(lightingShader.Program, "light.constant"), 1.0f);

glUniform1f(glGetUniformLocation(lightingShader.Program, "light.linear"), 0.09);

glUniform1f(glGetUniformLocation(lightingShader.Program, "light.quadratic"),

0.032);

// Set material properties

glUniform1f(glGetUniformLocation(lightingShader.Program, "material.shininess"),

32.0f);

// Create camera transformations

glm::mat4 view;

view = camera.GetViewMatrix();

glm::mat4 projection = glm::perspective(camera.Zoom, (GLfloat)WIDTH /

(GLfloat)HEIGHT, 0.1f, 100.0f);

// Get the uniform locations

GLint modelLoc = glGetUniformLocation(lightingShader.Program, "model");

GLint viewLoc = glGetUniformLocation(lightingShader.Program, "view");

GLint projLoc = glGetUniformLocation(lightingShader.Program, "projection");

// Pass the matrices to the shader

glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));

glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));

// Bind diffuse map

glActiveTexture(GL_TEXTURE0);

glBindTexture(GL_TEXTURE_2D, diffuseMap);

// Bind specular map

glActiveTexture(GL_TEXTURE1);

glBindTexture(GL_TEXTURE_2D, specularMap);

7.定义10个不同的箱子位置，为每个箱子生成不同的模型矩阵，每个模型矩阵包含相

应的本地到世界变换：

glm::mat4 model;

glBindVertexArray(containerVAO);

for (GLuint i = 0; i < 10; i++)

{

model = glm::mat4();

model = glm::translate(model, cubePositions[i]);

GLfloat angle = 20.0f * i;

model = glm::rotate(model, angle, glm::vec3(1.0f, 0.3f, 0.5f));

glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));

glDrawArrays(GL_TRIANGLES, 0, 36);

}

glBindVertexArray(0);

8.按照相似步骤编写点光源和聚光灯的代码，并修改相应的片段着色器。

五、实验结果

六、实验体会

这是实验是学会在3D场景中实现不同的光照效果——定向光、点光源和聚光灯。这次实验非常有意思，绘制出场景在平时玩的游戏中也经常看到。在实验中，要注意各光源的特点，将这些特点用数学语言描述出来，再转换为代码，这个过程对我们来说重要。