LearnOpenGL 光照贴图
2020-10-05 本文已影响0人
li_礼光
漫反射贴图
我们希望通过某种方式对每个原始像素独立设置diffuse颜色。有可以让我们基于物体原始像素的位置来获取颜色值的系统吗？
这可能听起来极其相似，坦白来讲我们使用这样的系统已经有一段时间了。听起来很像在一个LearnOpenGL 纹理中谈论的纹理，它基本就是一个纹理。我们其实是使用同一个潜在原则下的不同名称：使用一张图片覆盖住物体，以便我们为每个原始像素索引独立颜色值。在光照场景中，通过纹理来呈现一个物体的diffuse颜色，这个做法被称做漫反射贴图(Diffuse texture)(因为3D建模师就是这么称呼这个做法的)。
着色器中使用漫反射贴图和纹理教程介绍的一样。这次我们把纹理以sampler2D类型储存在Material结构体中。我们使用diffuse贴图替代早期定义的vec3类型的diffuse颜色。
要记住的是sampler2D也叫做模糊类型，这意味着我们不能以某种类型对它实例化，只能用uniform定义它们。如果我们用结构体而不是uniform实例化（就像函数的参数那样），GLSL会抛出奇怪的错误；这同样也适用于其他模糊类型。
这里跟纹理贴图的做法差不多, 跟LearnOpenGL 材质中的做法相似
因为要用到纹理,所以要重新处理立方体的纹理坐标.
//顶点数据 法线 纹理坐标
-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,
....
修改顶点着色器
layout (location = 2) in vec2 texCoords; //纹理数据源输入(2D)
out vec2 TexCoords;//把片元着色器的纹理从这里输出
....
main {
....
TexCoords = texCoords;
}
修改片段着色器
struct Material {
sampler2D ambient;
sampler2D diffuse;
sampler2D specular;
float shininess;//镜面反射散射因子(半径).
};
uniform Material material;//材质
...
main {
...
//环境颜色 = 光源颜色 × 环境光照强度 × 贴图
vec3 ambient = lightColor * light.ambientStrength * vec3(texture(material.ambient, TexCoords));
//漫反射颜色 = 光源颜色 × 漫反射因子(diffuseFactor) × 漫反射光照强度 × 贴图
...
vec3 diffuse = lightColor * diffuseFactor * light.diffuseStrength * vec3(texture(material.diffuse, TexCoords));
}
跟LearnOpenGL 材质不同的是. 因为修改了材质结构体的类型属性. 所以本来
vec3 diffuse = lightColor * material.ambient * diffuseFactor * light.diffuseStrength;
中的material.ambient替换为
vec3(texture(material.ambient, TexCoords))
Shader
//顶点着色器程序
static char *myLightMapsVertexShaderStr = SHADER(
\#version 330 core\n
layout (location = 0) in vec3 position; //顶点数据源输入
layout (location = 1) in vec3 normal; //法向量
layout (location = 2) in vec2 texCoords; //纹理数据源输入(2D)
uniform mat4 myProjection;//投影矩阵
uniform mat4 myView;//观察矩阵
uniform mat4 myModel;//模型矩阵
out vec3 Normal;//法线向量
out vec3 FragPos;//片段位置
out vec2 TexCoords;//把片元着色器的纹理从这里输出
void main()
{
gl_Position = myProjection * myView * myModel * vec4(position, 1.0f);
Normal = normal;
FragPos = vec3(myModel * vec4(position, 1.0f) );
TexCoords = texCoords;
}
);
//片元着色器程序
static char *myLightMapsFragmentShaderSrc = SHADER(
\#version 330 core\n
//材质
/**
要记住的是sampler2D也叫做模糊类型，这意味着我们不能以某种类型对它实例化，只能用uniform定义它们。
如果我们用结构体而不是uniform实例化（就像函数的参数那样），GLSL会抛出奇怪的错误；这同样也适用于其他模糊类型。
*/
struct Material {
sampler2D diffuse;
sampler2D specular;
float shininess;//镜面反射散射因子(半径).
};
uniform Material material;//材质
//光照强度
struct Light {
vec3 position;
vec3 ambient;//环境光照
vec3 diffuse;//漫反射光照
vec3 specular;//镜面反射光照
};
uniform Light light;
in vec3 Normal;
in vec3 FragPos;
in vec2 TexCoords;
uniform vec3 lightColor;//光照颜色
uniform vec3 lightPos;//光源位置
uniform vec3 viewPos;//镜面反射
out vec4 color;
void main()
{
//环境光ambient
//环境颜色 = 光源颜色 × 环境光照强度 × 贴图
vec3 ambient = lightColor * light.ambient * vec3(texture(material.diffuse, TexCoords));
//漫反射diffuse
//DiffuseFactor = max(0, dot(N, L))
//漫反射颜色 = 光源颜色 × 漫反射因子(diffuseFactor) × 漫反射光照强度 × 贴图
vec3 norm = normalize(Normal);
vec3 lightDir = normalize(lightPos - FragPos);
float diffuseFactor = max(dot(norm, lightDir),0.0);
vec3 diffuse = lightColor * diffuseFactor * light.diffuse * vec3(texture(material.diffuse, TexCoords));
//镜面反射specular
//R=reflect(L, N)
//SpecularFactor = pow(max(dot(R,V),0.0), shininess)
//镜面反射颜色 = 光源颜色 × 镜面反射因子(SpecularFactor) × 镜面光照强度 × 贴图
vec3 viewDir = normalize(viewPos - FragPos);
vec3 reflectDir = reflect(-lightDir , norm);
float specularFactor = pow(max(dot(viewDir, reflectDir),0.0),material.shininess);
vec3 specular = lightColor * specularFactor * light.specular * vec3(texture(material.specular, TexCoords));
//最终片段颜色：环境颜色+漫反射颜色+镜面反射颜色
vec3 result = ambient + diffuse + specular;
color = vec4(result , 1.0f);
}
);
顶点数据
GLfloat myLightMapsVertices[] = {
//顶点数据 法线 纹理坐标
-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, 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, 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, 0.0f,
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, 1.0f,
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, 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, 1.0f, 0.0f,
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, 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, 0.0f, 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, 1.0f, 0.0f,
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, 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, 0.0f, 0.0f,
};
程序
#include <iostream>
#include "MyLightMaps.hpp"
#include "MyProgram.hpp"
#include "MyLightMapsShader.h"
#include "MyLightMapsVertices.h"
#include "glm.hpp"
#include "matrix_transform.hpp"
#include "type_ptr.hpp"
#define STB_IMAGE_IMPLEMENTATION
#define STB_IMAGE_STATIC
#include "stb_image.h"
int runMyLightMapsCube() {
int result = glfwInit();
if (result == GL_FALSE) {
printf("glfwInit 初始化失败");
return -1;
}
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GLFW_TRUE);
GLFWwindow *window = glfwCreateWindow(600, 400, "My Opengl Window", NULL, NULL);
if(!window) {
printf("window 创建失败");
}
glfwMakeContextCurrent(window);
gladLoadGLLoader((GLADloadproc)glfwGetProcAddress);
//切换为纹理着色器程序
MyProgram myProgram = MyProgram(myLightMapsVertexShaderStr, myLightMapsFragmentShaderSrc);
///
GLuint VBO , VAO ;
unsigned int squareIndicesCount = 0;
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(myLightMapsVertices), myLightMapsVertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(0 * sizeof(GLfloat)));
glEnableVertexAttribArray(0);
//法线
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
glEnableVertexAttribArray(1);
//纹理
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(6 * sizeof(GLfloat)));
glEnableVertexAttribArray(2);
//解绑VAO
glBindVertexArray(0);
squareIndicesCount = sizeof(myLightMapsVertices)/(sizeof(myLightMapsVertices[0]) * 8);
glEnable(GL_DEPTH_TEST);
//加载纹理
unsigned int diffuseMaps_texture;
unsigned char *diffuseMaps_data;
int diffuseMaps_width, diffuseMaps_height, diffuseMaps_nrChannels;
glGenTextures(1, &diffuseMaps_texture);
glBindTexture(GL_TEXTURE_2D, diffuseMaps_texture);
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);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
diffuseMaps_data = stbi_load( "/Users/liliguang/Desktop/LearnOpengl/LearnOpenGl/LearnOpenGl/Demo/Common/ImgSources/box.png" , &diffuseMaps_width, &diffuseMaps_height, &diffuseMaps_nrChannels, 0);
if (diffuseMaps_data)
{
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, diffuseMaps_width, diffuseMaps_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, diffuseMaps_data);
glGenerateMipmap(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, 0);
}
else
{
std::cout << "Failed to load texture" << std::endl;
}
stbi_image_free(diffuseMaps_data);
unsigned int specularMaps_texture;
unsigned char *specularMaps_data;
int specularMaps_width, specularMaps_height, specularMaps_nrChannels;
glGenTextures(1, &specularMaps_texture);
glBindTexture(GL_TEXTURE_2D, specularMaps_texture);
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);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
specularMaps_data = stbi_load( "/Users/liliguang/Desktop/LearnOpengl/LearnOpenGl/LearnOpenGl/Demo/Common/ImgSources/box_specular.png" , &specularMaps_width, &specularMaps_height, &specularMaps_nrChannels, 0);
if (specularMaps_data)
{
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, specularMaps_width, specularMaps_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, specularMaps_data);
glGenerateMipmap(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, 0);
}
else
{
std::cout << "Failed to load texture" << std::endl;
}
stbi_image_free(specularMaps_data);
//材质-光照贴图
glUseProgram(myProgram.program);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, diffuseMaps_texture);
glUniform1i(glGetUniformLocation(myProgram.program, "material.diffuse"), 0);//环境贴图
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, specularMaps_texture);
glUniform1i(glGetUniformLocation(myProgram.program, "material.specular"), 1);//环境贴图
//进行绘制
while(!glfwWindowShouldClose(window)){
glfwPollEvents();
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//================================================
glm::mat4 model = glm::mat4(1.0f);
glm::mat4 view = glm::mat4(1.0f);
glm::mat4 projection = glm::mat4(1.0f);
GLint myModelLoc = glGetUniformLocation(myProgram.program,"myModel");
GLint myViewLoc = glGetUniformLocation(myProgram.program,"myView");
GLint myProjectionLoc = glGetUniformLocation(myProgram.program,"myProjection");
projection = glm::perspective(glm::radians(60.0f), 1.0f, 0.01f, 100.f);//投影矩阵
glUniformMatrix4fv(myProjectionLoc, 1, GL_FALSE, glm::value_ptr(projection));
glUniformMatrix4fv(myModelLoc, 1, GL_FALSE, glm::value_ptr(model));
// Material
glm::vec3 MaterialEye = glm::vec3(2.0f, 2.0f, 2.0f);
glm::vec3 MaterialCenter = glm::vec3(0.0f, 0.0f, 0.0f);
glm::vec3 MaterialUp = glm::vec3(0.0f, 1.0f, 0.0f);
glBindVertexArray(VAO);
view = glm::lookAt(MaterialEye, //摄像机位置
MaterialCenter, //目标
MaterialUp); //上向量
//================================================
//================================================
//镜面反射半径
GLint matShineLoc = glGetUniformLocation(myProgram.program, "material.shininess");
glUniform1f(matShineLoc, 64.0f);
//光照强度
GLint lightAmbientLoc = glGetUniformLocation(myProgram.program, "light.ambient");
GLint lightDiffuseLoc = glGetUniformLocation(myProgram.program, "light.diffuse");
GLint lightSpecularLoc = glGetUniformLocation(myProgram.program, "light.specular");
glUniform3f(lightAmbientLoc, 0.6f, 0.6f, 0.6f);
glUniform3f(lightDiffuseLoc, 0.9f, 0.9f, 0.9f);
glUniform3f(lightSpecularLoc, 1.0f, 1.0f, 1.0f);
//光源位置
GLint myLightPosLoc = glGetUniformLocation(myProgram.program,"lightPos");
glUniform3f(myLightPosLoc,1.0f,0.0f,4.0f); //
//镜面反射
GLint myViewPosLoc = glGetUniformLocation(myProgram.program,"viewPos");
glUniform3f(myViewPosLoc,0.0,0.0f,3.0f); //
//光照颜色
GLint lightColorLoc = glGetUniformLocation(myProgram.program,"lightColor");
glUniform3f(lightColorLoc,1.0f,1.0f,1.0f); //白光
glUniformMatrix4fv(myViewLoc, 1, GL_FALSE, glm::value_ptr(view));
glDrawArrays(GL_TRIANGLES, 0, squareIndicesCount);
glBindVertexArray(0);
glfwSwapBuffers(window);
}
//程序销毁
glfwTerminate();
return 1;
}
效果
光照贴图
