計算機圖形學作業( 六):畫一個平面和一些立方體並實現陰影映射
引入依賴庫
本次實驗需要用到 OpenGL 官方的 Camera 庫和 Shader 庫。Camera 庫內包含一個攝像機類,可以幫助我們快速地生成和使用攝像機,點擊此處下載。Shader 庫是內包含一個 Shader 類,可以幫助我們快速地聲明和使用頂點着色器和片段着色器,我們只需新建頂點着色器和片段着色器代碼文件,就可以在主函數中利用 Shader 的構造函數構造出着色器,並使用其中的函數控制着色器,點擊此處下載
除此之外,本次實驗需要用到加載紋理的第三方庫stb_image.h
,點擊此處下載。下載之後,在項目中引入文件頭文件stb_image.h
,並新建一個.cpp
文件,裏面內容爲:
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"
之後,我們便可以使用stb_image.h
內置的函數加載紋理了。
陰影映射
原理
在深度測試中,在深度緩衝裏的一個值是攝像機視角下,對應於一個片元的一個0到1之間的深度值。我們從光源的透視圖來渲染場景,並把深度值的結果儲存到紋理中,這樣就能對光源的透視圖所見的最近的深度值進行採樣。最終,深度值就會顯示從光源的透視圖下見到的第一個片元了。我們管儲存在紋理中的所有這些深度值,叫做深度貼圖或陰影貼圖。
利用每個片元的深度值,我們可比較在同一條光線上的點誰距離光源更近,距離最近的點是可視的被光線照射的點,而距離較遠的則被視爲陰影。
深度貼圖
第一步我們需要生成一張深度貼圖。深度貼圖是從光的透視圖裏渲染的深度紋理,用它計算陰影。因爲我們需要將場景的渲染結果儲存到一個紋理中,我們將再次需要幀緩衝。
首先,我們要爲渲染的深度貼圖創建一個幀緩衝對象:
GLuint depthMapFBO;
glGenFramebuffers(1, &depthMapFBO);
然後,創建一個2D紋理,提供給幀緩衝的深度緩衝使用:
const GLuint SHADOW_WIDTH = 1024, SHADOW_HEIGHT = 1024;
GLuint depthMap;
glGenTextures(1, &depthMap);
glBindTexture(GL_TEXTURE_2D, depthMap);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT,
SHADOW_WIDTH, SHADOW_HEIGHT, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
把我們把生成的深度紋理作爲幀緩衝的深度緩衝:
glBindFramebuffer(GL_FRAMEBUFFER, depthMapFBO);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, depthMap, 0);
glDrawBuffer(GL_NONE);
glReadBuffer(GL_NONE);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
合理配置將深度值渲染到紋理的幀緩衝後,我們就可以開始生成深度貼圖:
// 1. 首選渲染深度貼圖
glViewport(0, 0, SHADOW_WIDTH, SHADOW_HEIGHT);
glBindFramebuffer(GL_FRAMEBUFFER, depthMapFBO);
glClear(GL_DEPTH_BUFFER_BIT);
ConfigureShaderAndMatrices();
RenderScene();
glBindFramebuffer(GL_FRAMEBUFFER, 0);
// 2. 像往常一樣渲染場景,但這次使用深度貼圖
glViewport(0, 0, SCR_WIDTH, SCR_HEIGHT);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
ConfigureShaderAndMatrices();
glBindTexture(GL_TEXTURE_2D, depthMap);
RenderScene();
最終效果如下:
渲染陰影
渲染陰影主要在像素着色器中進行,在片段着色器中檢驗一個片元是否在陰影之中,然後在頂點着色器中進行光空間的變換。着色器的代碼在後面給出。
然後,在主函數中,設置着色器的各種屬性:
shader.use();
glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)WINDOW_WIDTH / (float)WINDOW_HEIGHT, 0.1f, 100.0f);
glm::mat4 view = camera.GetViewMatrix();
shader.setMat4("projection", projection);
shader.setMat4("view", view);
// set light uniforms
shader.setVec3("viewPos", camera.Position);
shader.setVec3("lightPos", lightPos);
shader.setMat4("lightSpaceMatrix", lightSpaceMatrix);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, woodTexture);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, depthMap);
renderScene(shader);
最終的效果如下:
陰影優化(加分項)
陰影失真
運行程序後,放大觀察到有明顯的線條樣式:
爲了解決這個問題,我們需要在片段着色器重稍微修改:
float bias = max(0.05 * (1.0 - dot(normal, lightDir)), 0.005);
使用了偏移量後,所有采樣點都獲得了比表面深度更小的深度值,這樣整個表面就正確地被照亮,沒有任何陰影。
PCF
運行程序後,放大觀察到鋸齒現象:
我們要在片段着色器中稍微修改以下部分:
float shadow = 0.0;
vec2 texelSize = 1.0 / textureSize(shadowMap, 0);
for(int x = -1; x <= 1; ++x)
{
for(int y = -1; y <= 1; ++y)
{
float pcfDepth = texture(shadowMap, projCoords.xy + vec2(x, y) * texelSize).r;
shadow += currentDepth - bias > pcfDepth ? 1.0 : 0.0;
}
}
shadow /= 9.0;
以上解決方案叫做PCF,這是一種多個不同過濾方式的組合,它產生柔和陰影,使它們出現更少的鋸齒塊和硬邊。核心思想是從深度貼圖中多次採樣,每一次採樣的紋理座標都稍有不同。每個獨立的樣本可能在也可能不再陰影中。所有的次生結果接着結合在一起,進行平均化,我們就得到了柔和陰影。
代碼
以下是着色器代碼:
debugQuad.vs
#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec2 aTexCoords;
out vec2 TexCoords;
void main()
{
TexCoords = aTexCoords;
gl_Position = vec4(aPos, 1.0);
}
debugQuadDepth.fs
#version 330 core
out vec4 FragColor;
in vec2 TexCoords;
uniform sampler2D depthMap;
uniform float near_plane;
uniform float far_plane;
// required when using a perspective projection matrix
float LinearizeDepth(float depth)
{
float z = depth * 2.0 - 1.0; // Back to NDC
return (2.0 * near_plane * far_plane) / (far_plane + near_plane - z * (far_plane - near_plane));
}
void main()
{
float depthValue = texture(depthMap, TexCoords).r;
// FragColor = vec4(vec3(LinearizeDepth(depthValue) / far_plane), 1.0); // perspective
FragColor = vec4(vec3(depthValue), 1.0); // orthographic
}
shadowMappingDepth.vs
#version 330 core
layout (location = 0) in vec3 aPos;
uniform mat4 lightSpaceMatrix;
uniform mat4 model;
void main()
{
gl_Position = lightSpaceMatrix * model * vec4(aPos, 1.0);
}
shadowMappingDepth.fs
#version 330 core
void main()
{
// gl_FragDepth = gl_FragCoord.z;
}
shadowMapping.vs
#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aNormal;
layout (location = 2) in vec2 aTexCoords;
out vec2 TexCoords;
out VS_OUT {
vec3 FragPos;
vec3 Normal;
vec2 TexCoords;
vec4 FragPosLightSpace;
} vs_out;
uniform mat4 projection;
uniform mat4 view;
uniform mat4 model;
uniform mat4 lightSpaceMatrix;
void main()
{
vs_out.FragPos = vec3(model * vec4(aPos, 1.0));
vs_out.Normal = transpose(inverse(mat3(model))) * aNormal;
vs_out.TexCoords = aTexCoords;
vs_out.FragPosLightSpace = lightSpaceMatrix * vec4(vs_out.FragPos, 1.0);
gl_Position = projection * view * model * vec4(aPos, 1.0);
}
shadowMapping.fs
#version 330 core
out vec4 FragColor;
in VS_OUT {
vec3 FragPos;
vec3 Normal;
vec2 TexCoords;
vec4 FragPosLightSpace;
} fs_in;
uniform sampler2D diffuseTexture;
uniform sampler2D shadowMap;
uniform vec3 lightPos;
uniform vec3 viewPos;
float ShadowCalculation(vec4 fragPosLightSpace)
{
// perform perspective divide
vec3 projCoords = fragPosLightSpace.xyz / fragPosLightSpace.w;
// transform to [0,1] range
projCoords = projCoords * 0.5 + 0.5;
// get closest depth value from light's perspective (using [0,1] range fragPosLight as coords)
float closestDepth = texture(shadowMap, projCoords.xy).r;
// get depth of current fragment from light's perspective
float currentDepth = projCoords.z;
// calculate bias (based on depth map resolution and slope)
vec3 normal = normalize(fs_in.Normal);
vec3 lightDir = normalize(lightPos - fs_in.FragPos);
float bias = max(0.05 * (1.0 - dot(normal, lightDir)), 0.005);
// check whether current frag pos is in shadow
// float shadow = currentDepth - bias > closestDepth ? 1.0 : 0.0;
// PCF
float shadow = 0.0;
vec2 texelSize = 1.0 / textureSize(shadowMap, 0);
for(int x = -1; x <= 1; ++x)
{
for(int y = -1; y <= 1; ++y)
{
float pcfDepth = texture(shadowMap, projCoords.xy + vec2(x, y) * texelSize).r;
shadow += currentDepth - bias > pcfDepth ? 1.0 : 0.0;
}
}
shadow /= 9.0;
// keep the shadow at 0.0 when outside the far_plane region of the light's frustum.
if(projCoords.z > 1.0)
shadow = 0.0;
return shadow;
}
void main()
{
vec3 color = texture(diffuseTexture, fs_in.TexCoords).rgb;
vec3 normal = normalize(fs_in.Normal);
vec3 lightColor = vec3(0.3);
// ambient
vec3 ambient = 0.3 * color;
// diffuse
vec3 lightDir = normalize(lightPos - fs_in.FragPos);
float diff = max(dot(lightDir, normal), 0.0);
vec3 diffuse = diff * lightColor;
// specular
vec3 viewDir = normalize(viewPos - fs_in.FragPos);
vec3 reflectDir = reflect(-lightDir, normal);
float spec = 0.0;
vec3 halfwayDir = normalize(lightDir + viewDir);
spec = pow(max(dot(normal, halfwayDir), 0.0), 64.0);
vec3 specular = spec * lightColor;
// calculate shadow
float shadow = ShadowCalculation(fs_in.FragPosLightSpace);
vec3 lighting = (ambient + (1.0 - shadow) * (diffuse + specular)) * color;
FragColor = vec4(lighting, 1.0);
}
以下是主程序代碼:
main.cpp
#include <iostream>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include "imgui.h"
#include "imgui_impl_glfw.h"
#include "imgui_impl_opengl3.h"
#include <glm.hpp>
#include <gtc/matrix_transform.hpp>
#include <gtc/type_ptr.hpp>
// 加載紋理的庫
#include "stb_image.h"
//使用了官方的shader庫文件,可以更方便地操作shader
//注意,使用官方庫操作shadder時,自己寫的頂點和片段着色器代碼必須另外寫成文件
//然後把文件路徑傳入shader.h提供的構造函數
#include "shader.h"
#include "camera.h"
using namespace std;
const int WINDOW_WIDTH = 1000;
const int WINDOW_HEIGHT = 800;
void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void processInput(GLFWwindow* window);
unsigned int loadTexture(const char *path);
void renderScene(const Shader &shader);
void renderCube();
void renderQuad();
//camera的位置與後面物體的view向量相反
Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
//鼠標位置
float mouseX = (float)WINDOW_WIDTH / 2.0;
float mouseY = (float)WINDOW_HEIGHT / 2.0;
bool firstMouse = true;
//每一幀間隔時間
float deltaTime = 0.0f;
//上一幀的時刻
float lastFrame = 0.0f;
unsigned int planeVAO;
int main() {
//初始化opengl窗口和配置
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow* window = glfwCreateWindow(WINDOW_WIDTH, WINDOW_HEIGHT, "LearnOpenGL", NULL, NULL);
if (window == NULL) {
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
glfwSetCursorPosCallback(window, mouse_callback);
glfwSetScrollCallback(window, scroll_callback);
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
//創建並綁定ImGui
const char* glsl_version = "#version 130";
IMGUI_CHECKVERSION();
ImGui::CreateContext();
ImGuiIO& io = ImGui::GetIO(); (void)io;
ImGui::StyleColorsDark();
ImGui_ImplGlfw_InitForOpenGL(window, true);
ImGui_ImplOpenGL3_Init(glsl_version);
// 深度測試
glEnable(GL_DEPTH_TEST);
// 初始化shader
Shader shader("shadowMappingVs.vs", "shadowMappingFs.fs");
Shader simpleDepthShader("shadowMappingDepthVs.vs", "shadowMappingDepthFs.fs");
Shader debugDepthQuad("debugQuadVs.vs", "debugQuadDepthFs.fs");
// 平面座標
GLfloat planeVertices[] = {
// 位置 // 法向量 // 紋理座標
25.0f, -0.5f, 25.0f, 0.0f, 1.0f, 0.0f, 25.0f, 0.0f,
-25.0f, -0.5f, -25.0f, 0.0f, 1.0f, 0.0f, 0.0f, 25.0f,
-25.0f, -0.5f, 25.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f,
25.0f, -0.5f, 25.0f, 0.0f, 1.0f, 0.0f, 25.0f, 0.0f,
25.0f, -0.5f, -25.0f, 0.0f, 1.0f, 0.0f, 25.0f, 25.0f,
-25.0f, -0.5f, -25.0f, 0.0f, 1.0f, 0.0f, 0.0f, 25.0f
};
// 平面的VAO
unsigned int planeVBO;
glGenVertexArrays(1, &planeVAO);
glGenBuffers(1, &planeVBO);
glBindVertexArray(planeVAO);
glBindBuffer(GL_ARRAY_BUFFER, planeVBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(planeVertices), &planeVertices, GL_STATIC_DRAW);
// 屬性位置值爲0的頂點屬性,有3個值,頂點着色器總參數大小爲8個float,位置屬性偏移爲0
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
glEnableVertexAttribArray(2);
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(6 * sizeof(GLfloat)));
glBindVertexArray(0);
// 加載紋理
unsigned int woodTexture = loadTexture("wood.jpg");
// 爲渲染的深度貼圖創建一個幀緩衝對象
unsigned int depthMapFBO;
glGenFramebuffers(1, &depthMapFBO);
// 創建一個2D紋理,提供給幀緩衝的深度緩衝使用
const unsigned int SHADOW_WIDTH = 1024, SHADOW_HEIGHT = 1024;
unsigned int depthMap;
glGenTextures(1, &depthMap);
glBindTexture(GL_TEXTURE_2D, depthMap);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, SHADOW_WIDTH, SHADOW_HEIGHT, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
float borderColor[] = { 1.0, 1.0, 1.0, 1.0 };
glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, borderColor);
// 把生成的深度紋理作爲幀緩衝的深度緩衝
glBindFramebuffer(GL_FRAMEBUFFER, depthMapFBO);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, depthMap, 0);
glDrawBuffer(GL_NONE);
glReadBuffer(GL_NONE);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
// 使用shader
shader.use();
shader.setInt("diffuseTexture", 0);
shader.setInt("shadowMap", 1);
debugDepthQuad.use();
// 設置shader屬性
debugDepthQuad.setInt("depthMap", 0);
bool enable_camera = true;
bool show_window = true;
glm::vec3 lightPos(-2.0f, 4.0f, -1.0f);
while (!glfwWindowShouldClose(window)) {
if (enable_camera) {
//告訴glfw獲取我們的鼠標
glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
}
else {
glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_NORMAL);
}
//計算當前時間和幀間隔時間,爲了使移動更平滑
float currentFrame = glfwGetTime();
deltaTime = currentFrame - lastFrame;
lastFrame = currentFrame;
processInput(window);
//清除屏幕
glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glm::mat4 lightProjection, lightView;
glm::mat4 lightSpaceMatrix;
float near_plane = 1.0f, far_plane = 7.5f;
// 計算觀察和投影矩陣
lightProjection = glm::ortho(-10.0f, 10.0f, -10.0f, 10.0f, near_plane, far_plane);
lightView = glm::lookAt(lightPos, glm::vec3(0.0f), glm::vec3(0.0, 1.0, 0.0));
lightSpaceMatrix = lightProjection * lightView;
// 應用到shader
simpleDepthShader.use();
simpleDepthShader.setMat4("lightSpaceMatrix", lightSpaceMatrix);
glViewport(0, 0, SHADOW_WIDTH, SHADOW_HEIGHT);
glBindFramebuffer(GL_FRAMEBUFFER, depthMapFBO);
glClear(GL_DEPTH_BUFFER_BIT);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, woodTexture);
renderScene(simpleDepthShader);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
// 重置viewport
glViewport(0, 0, WINDOW_WIDTH, WINDOW_HEIGHT);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glViewport(0, 0, WINDOW_WIDTH, WINDOW_HEIGHT);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
shader.use();
glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)WINDOW_WIDTH / (float)WINDOW_HEIGHT, 0.1f, 100.0f);
glm::mat4 view = camera.GetViewMatrix();
shader.setMat4("projection", projection);
shader.setMat4("view", view);
// set light uniforms
shader.setVec3("viewPos", camera.Position);
shader.setVec3("lightPos", lightPos);
shader.setMat4("lightSpaceMatrix", lightSpaceMatrix);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, woodTexture);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, depthMap);
renderScene(shader);
// 渲染深度圖
debugDepthQuad.use();
debugDepthQuad.setFloat("near_plane", near_plane);
debugDepthQuad.setFloat("far_plane", far_plane);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, depthMap);
//renderQuad();
//創建imgui
ImGui_ImplOpenGL3_NewFrame();
ImGui_ImplGlfw_NewFrame();
ImGui::NewFrame();
ImGui::Begin("Edit cube", &show_window, ImGuiWindowFlags_MenuBar);
if (ImGui::Button("enable camera")) {
if (enable_camera) {
enable_camera = false;
}
else {
enable_camera = true;
}
}
ImGui::End();
ImGui::Render();
int display_w, display_h;
glfwMakeContextCurrent(window);
glfwGetFramebufferSize(window, &display_w, &display_h);
glViewport(0, 0, display_w, display_h);
ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
glfwPollEvents();
glfwSwapBuffers(window);
}
glDeleteVertexArrays(1, &planeVAO);
glDeleteBuffers(1, &planeVBO);
glfwTerminate();
return 0;
}
void framebuffer_size_callback(GLFWwindow* window, int width, int height) {
glViewport(0, 0, width, height);
}
void processInput(GLFWwindow* window) {
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) {
glfwSetWindowShouldClose(window, true);
}
if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
camera.ProcessKeyboard(FORWARD, deltaTime);
if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
camera.ProcessKeyboard(BACKWARD, deltaTime);
if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
camera.ProcessKeyboard(LEFT, deltaTime);
if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
camera.ProcessKeyboard(RIGHT, deltaTime);
}
//鼠標移動
void mouse_callback(GLFWwindow* window, double xpos, double ypos) {
if (firstMouse)
{
mouseX = xpos;
mouseY = ypos;
firstMouse = false;
}
float xoffset = xpos - mouseX;
float yoffset = mouseY - ypos;
mouseX = xpos;
mouseY = ypos;
camera.ProcessMouseMovement(xoffset, yoffset);
}
//鼠標放縮
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset) {
camera.ProcessMouseScroll(yoffset);
}
unsigned int loadTexture(char const * path)
{
unsigned int textureID;
glGenTextures(1, &textureID);
int width, height, nrComponents;
unsigned char *data = stbi_load(path, &width, &height, &nrComponents, 0);
if (data)
{
GLenum format;
if (nrComponents == 1)
format = GL_RED;
else if (nrComponents == 3)
format = GL_RGB;
else if (nrComponents == 4)
format = GL_RGBA;
glBindTexture(GL_TEXTURE_2D, textureID);
glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, format == GL_RGBA ? GL_CLAMP_TO_EDGE : GL_REPEAT); // for this tutorial: use GL_CLAMP_TO_EDGE to prevent semi-transparent borders. Due to interpolation it takes texels from next repeat
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, format == GL_RGBA ? GL_CLAMP_TO_EDGE : GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
stbi_image_free(data);
}
else
{
std::cout << "Texture failed to load at path: " << path << std::endl;
stbi_image_free(data);
}
return textureID;
}
// 渲染3D場景
void renderScene(const Shader &shader)
{
// floor
glm::mat4 model = glm::mat4(1.0f);
shader.setMat4("model", model);
glBindVertexArray(planeVAO);
glDrawArrays(GL_TRIANGLES, 0, 6);
// cubes
model = glm::mat4(1.0f);
model = glm::translate(model, glm::vec3(0.0f, 1.5f, 0.0));
model = glm::scale(model, glm::vec3(0.5f));
shader.setMat4("model", model);
renderCube();
model = glm::mat4(1.0f);
model = glm::translate(model, glm::vec3(2.0f, 0.0f, 1.0));
model = glm::scale(model, glm::vec3(0.5f));
shader.setMat4("model", model);
renderCube();
model = glm::mat4(1.0f);
model = glm::translate(model, glm::vec3(-1.0f, 0.0f, 2.0));
model = glm::rotate(model, glm::radians(60.0f), glm::normalize(glm::vec3(1.0, 0.0, 1.0)));
model = glm::scale(model, glm::vec3(0.25));
shader.setMat4("model", model);
renderCube();
}
// renderCube() 渲染一個 3D 正方體
unsigned int cubeVAO = 0;
unsigned int cubeVBO = 0;
void renderCube()
{
// initialize (if necessary)
if (cubeVAO == 0)
{
float vertices[] = {
// back face
-1.0f, -1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f, // bottom-left
1.0f, 1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f, // top-right
1.0f, -1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f, // bottom-right
1.0f, 1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f, // top-right
-1.0f, -1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f, // bottom-left
-1.0f, 1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 0.0f, 1.0f, // top-left
// front face
-1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, // bottom-left
1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, // bottom-right
1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, // top-right
1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, // top-right
-1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, // top-left
-1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, // bottom-left
// left face
-1.0f, 1.0f, 1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f, // top-right
-1.0f, 1.0f, -1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // top-left
-1.0f, -1.0f, -1.0f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f, // bottom-left
-1.0f, -1.0f, -1.0f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f, // bottom-left
-1.0f, -1.0f, 1.0f, -1.0f, 0.0f, 0.0f, 0.0f, 0.0f, // bottom-right
-1.0f, 1.0f, 1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f, // top-right
// right face
1.0f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, // top-left
1.0f, -1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f, // bottom-right
1.0f, 1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // top-right
1.0f, -1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f, // bottom-right
1.0f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, // top-left
1.0f, -1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, // bottom-left
// bottom face
-1.0f, -1.0f, -1.0f, 0.0f, -1.0f, 0.0f, 0.0f, 1.0f, // top-right
1.0f, -1.0f, -1.0f, 0.0f, -1.0f, 0.0f, 1.0f, 1.0f, // top-left
1.0f, -1.0f, 1.0f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f, // bottom-left
1.0f, -1.0f, 1.0f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f, // bottom-left
-1.0f, -1.0f, 1.0f, 0.0f, -1.0f, 0.0f, 0.0f, 0.0f, // bottom-right
-1.0f, -1.0f, -1.0f, 0.0f, -1.0f, 0.0f, 0.0f, 1.0f, // top-right
// top face
-1.0f, 1.0f, -1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, // top-left
1.0f, 1.0f , 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // bottom-right
1.0f, 1.0f, -1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, // top-right
1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // bottom-right
-1.0f, 1.0f, -1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, // top-left
-1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f // bottom-left
};
glGenVertexArrays(1, &cubeVAO);
glGenBuffers(1, &cubeVBO);
// fill buffer
glBindBuffer(GL_ARRAY_BUFFER, cubeVBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
// link vertex attributes
glBindVertexArray(cubeVAO);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(2);
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
}
// render Cube
glBindVertexArray(cubeVAO);
glDrawArrays(GL_TRIANGLES, 0, 36);
glBindVertexArray(0);
}
// renderQuad() renders a 1x1 XY quad in NDC
unsigned int quadVAO = 0;
unsigned int quadVBO;
void renderQuad()
{
if (quadVAO == 0)
{
float quadVertices[] = {
// positions // texture Coords
-1.0f, 1.0f, 0.0f, 0.0f, 1.0f,
-1.0f, -1.0f, 0.0f, 0.0f, 0.0f,
1.0f, 1.0f, 0.0f, 1.0f, 1.0f,
1.0f, -1.0f, 0.0f, 1.0f, 0.0f,
};
// setup plane VAO
glGenVertexArrays(1, &quadVAO);
glGenBuffers(1, &quadVBO);
glBindVertexArray(quadVAO);
glBindBuffer(GL_ARRAY_BUFFER, quadVBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(quadVertices), &quadVertices, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
}
glBindVertexArray(quadVAO);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glBindVertexArray(0);
}