OpenGL 未在启用深度缓冲区的情况下以 3D 绘制

【问题标题】：OpenGL not drawing in 3D with depth buffers enabledOpenGL 未在启用深度缓冲区的情况下以 3D 绘制
【发布时间】：2021-09-02 22:25:18
【问题描述】：

我花了 2 周时间尝试让 OpenGL 绘制 3D 立方体，但无论我做什么，它都没有真正绘制过立方体。如果我使用 glEnable(DEPTH_TEST) 启用深度测试，它根本不会渲染任何东西。如果我注释掉该函数，它会将所有顶点呈现为好像 z 值都是 0。我完全陷入困境，不知道我做错了什么。

这是我的主文件：https://pastebin.com/D8cEcJ4g

#include "Dependencies\glew\glew.h"
#include "Dependencies\freeglut\freeglut.h"
#include "Dependencies\soil\SOIL.h"
 
#include "glm/glm.hpp"
#include "glm/gtc/matrix_transform.hpp"
#include "glm/gtc/type_ptr.hpp"
 
#include <iostream>
 
#include "ShaderLoader.h";
#include "Camera.h"
 
#define BUTTON_UP   0
#define BUTTON_DOWN 1
 
GLuint program;
GLuint vao, vbo, ebo;
GLuint texture, texture2;
 
unsigned char keyState[255];
 
 
glm::vec3 vPosTrans = glm::vec3(-0.50f, -0.50f, 0.0f);//source
glm::vec3 vPosInit = vPosTrans;
glm::vec3 vPosDest = glm::vec3(0.50f, 0.50f, 0.0f);//destination
glm::vec3 vCurrentPos = vPosTrans;
 
bool Dest1or2 = true;
 
const GLfloat WIDTH = 800.0f, HEIGHT = 600.0f;
 
Camera* camera;
 
void init(){
    camera = new Camera(180.0f, WIDTH, HEIGHT, 0.0f, 100.0f);
 
    ShaderLoader shaderLoader;
    program = shaderLoader.CreateProgram("CoordSystem_Texture_QUAD.vs", "CoordSystem_Texture_QUAD.fs");
 
    glEnable(GL_DEPTH_TEST);
 
    glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
 
    // Set up vertex data (and buffer(s)) and attribute pointers
    GLfloat vertices[] = {
 
        //position              //color                 //texture coord   //Normals
        -1.01f, -1.01f, -1.01f, 1.0f, 0.0f, 0.0f,       0.0f, 1.0f,
        -1.01f, 1.01f, -1.01f,      0.0f, 1.0f, -0.0f,      0.0f, 0.0f,
        1.01f, 1.01f, -1.01f,       1.0f, 0.0f, -0.0f,      1.0f, 0.0f,
        1.01f, -1.01f, -1.01f,      0.0f, 1.0f,  1.0f,      1.0f, 1.0f,
 
        // Fill in the back face vertex data.
        -1.01f, -1.01f, 1.01f,      0.0f, 1.0f, 1.0f,       1.0f, 1.0f,
        1.01f, -1.01f, 1.01f,       1.0f, 0.0f, 1.0f,       0.0f, 1.0f,
        1.01f, 1.01f, 1.01f,        1.0f, 0.0f, 1.0f,       0.0f, 0.0f,
        -1.01f, 1.01f, 1.01f,       1.0f, 1.0f, 0.0f,       1.0f, 0.0f,
 
        // Fill in the top face vertex data.
        -1.01f, 1.01f, -1.01f,      0.0f, 1.0f, 0.0f,       0.0f, 1.0f,
        -1.01f, 1.01f, 1.01f,       1.0f, 0.0f, 1.0f,       0.0f, 0.0f,
        1.01f, 1.01f, 1.01f,        0.0f, 1.0f, 1.0f,       1.0f, 0.0f,
        1.01f, 1.01f, -1.01f,       1.0f, 1.0f, 0.0f,       1.0f, 1.0f,
 
        // Fill in the bottom face vertex data.
        -1.01f, -1.01f, -1.01f, 1.0f,  1.0f, 0.0f,      1.0f, 1.0f,
        1.01f, -1.01f, -1.01f,      0.0f,  1.0f, 1.0f,      0.0f, 1.0f,
        1.01f, -1.01f, 1.01f,       0.0f,  1.0f, 0.0f,      0.0f, 0.0f,
        -1.01f, -1.01f, 1.01f,      1.0f,  1.0f, 0.0f,      1.0f, 0.0f,
 
        // Fill in the left face vertex data.
        -1.01f, -1.01f, 1.01f,       1.0f, 1.0f, 0.0f,      0.0f, 1.0f,
        -1.01f, 1.01f, 1.01f,        1.0f, 0.0f, 1.0f,      0.0f, 0.0f,
        -1.01f, 1.01f, -1.01f,       1.0f, 0.0f, 1.0f,      1.0f, 0.0f,
        -1.01f, -1.01f, -1.01f,  1.0f, 1.0f, 0.0f,      1.0f, 1.0f,
 
        // Fill in the right face vertex data.
        1.01f, -1.01f, -1.01f,      1.0f, 1.0f, 0.0f,       0.0f, 1.0f,
        1.01f, 1.01f, -1.01f,       0.0f, 1.0f, 1.0f,       0.0f, 0.0f,
        1.01f, 1.01f, 1.01f,        1.0f, 0.0f, 1.0f,       1.0f, 0.0f,
        1.01f, -1.01f, 1.01f,       0.0f, 1.0f, 1.0f,       1.0f, 1.0f,
    };
 
    GLuint indices[] = {
        // front
        0, 1, 2,
        0, 2, 3,
        // top
        4, 5, 6,
        4, 6, 7,
        // back
        8, 9, 10,
        8, 10, 11,
        // bottom
        12, 13, 14,
        12, 14, 15,
        // left
        16, 17, 18,
        16, 18, 19,
        // right
        20, 21, 22,
        20, 22, 23,
    };
 
    //** VAO **
    // Generate vertex arrow object
    glGenVertexArrays(1, &vao);
    // Bind the Vertex Array Object to openGl context
    glBindVertexArray(vao);//otherwise glVertexAttribPointer
 
    //** VBO **
    // Then bind and set vertex buffer(s).
    // First paramter is how many buffers we have to create
    glGenBuffers(1, &vbo);
 
    // bind VBO to binding point, here it is GL_ARRAY_BUFFER
    // there are other binding points
    glBindBuffer(GL_ARRAY_BUFFER, vbo);//bind to context
    glBufferData(GL_ARRAY_BUFFER,
        sizeof(vertices),// GPU need to know how much memory needs to be allocated
        vertices,//copy data to GPU
        GL_STATIC_DRAW);// How to use the buffer - buffer is created and modified once
 
    //** EBO **
    glGenBuffers(1, &ebo);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER,
        sizeof(indices),
        indices,
        GL_STATIC_DRAW);
 
 
    // ** Attributes **
 
    //** Vertex Attribute **
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)0);
    glEnableVertexAttribArray(0);
 
    //** Color Attribute **
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
    glEnableVertexAttribArray(1);
 
    //** TexCoord attribute **
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(6 * sizeof(GLfloat)));
    glEnableVertexAttribArray(2);
 
    // It's always a good thing to unbind any buffer/array to prevent strange bugs
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindVertexArray(0);
 
    //** Load and bind texture 1 
    //--------------------------
    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);
 
 
    //** loadImage and create texture
    // Load image, create texture and generate mipmaps
    int width, height;
    unsigned char* image = SOIL_load_image("wall.jpg", &width, &height, 0, SOIL_LOAD_RGB);
    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);
    glBindTexture(GL_TEXTURE_2D, 0);
 
 
    // ** Load and Bind Texture 2
    //---------------------------
    glGenTextures(1, &texture2);
    glBindTexture(GL_TEXTURE_2D, texture2);
 
 
    //** loadImage and create texture
    // Load image, create texture and generate mipmaps
    unsigned char* image2 = SOIL_load_image("awesomeface.png", &width, &height, 0, SOIL_LOAD_RGB);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image2);
    glGenerateMipmap(GL_TEXTURE_2D);
    SOIL_free_image_data(image2);
    glBindTexture(GL_TEXTURE_2D, 0);
 
 
    // Set texture wrapping to GL_REPEAT (usually basic wrapping method)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    // Set texture filtering parameters
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 
}
 
void render(){
 
    glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
    // Draw our first triangle
    glUseProgram(program);
 
    //bind 
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texture);
    glUniform1i(glGetUniformLocation(program, "Texture"), 0);
 
    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, texture2);
    glUniform1i(glGetUniformLocation(program, "Texture2"), 1);
 
    glBindVertexArray(vao);
 
    // Draw Elements intead of vertex array 
    glDrawArrays(GL_QUADS, 0, 24);
    //glDrawElements(GL_TRIANGLES, 24, GL_UNSIGNED_INT, 0);
    glBindVertexArray(0);
 
    glutSwapBuffers();
}
 
void update(){
    GLfloat cameraSpeed = 0.05f;
    camera->setCameraSpeed(cameraSpeed);
 
    //currentTime uniform
    GLfloat currentTime = glutGet(GLUT_ELAPSED_TIME);
    currentTime = currentTime / 1000;
    GLint currentTimeLocation = glGetUniformLocation(program, "currentTime");
    glUniform1f(currentTimeLocation, currentTime);
 
    //transforms
    glm::mat4 transform = glm::mat4(1.0f);
    glm::vec3 vScaleVec = glm::vec3(0.51f, 0.51f, 0.0f);
 
    glm::mat4 model = glm::mat4(1.0);
 
    if (keyState[(unsigned char)'w'] == BUTTON_DOWN) {
        camera->moveForward();
        std::cout << "e";
    }
    if (keyState[(unsigned char)'s'] == BUTTON_DOWN) {
        camera->moveBack();
        std::cout << "A";
    }
 
    camera->Update();
 
    //glm::mat4 projection = glm::perspective(45.0f, (GLfloat)WIDTH / (GLfloat)HEIGHT, 0.1f, 100.0f);
    glm::mat4 projection = camera->getProjectionMatrix();
 
    glm::mat4 view = glm::lookAt(camera->getCameraPos(), camera->getCameraPos() + camera->getCameraFront(), camera->getCameraUp());
 
    //glm::mat4 view = glm::lookAt(glm::vec3(1, 1, 0), glm::vec3(0, 1, 0), glm::vec3(0, 0, 1));
 
    GLfloat radius = 3.5f;
    GLfloat camX = sin(currentTime) * radius;
    GLfloat camZ = cos(currentTime) * radius;
 
    //glm::mat4 view = glm::lookAt(
    //     glm::vec3(camX, 0.0, camZ),
    //     glm::vec3(0.0, 0.0, 0.0),
    //     glm::vec3(0.0, 1.0, 0.0));
 
    transform = glm::scale(transform, vScaleVec);
    glm::vec3(0.65f, 0.65f, 0.65f);
    //transform = glm::rotate(transform, 90.0f, glm::vec3(0.0, 0.0, 1.0));
    if (vCurrentPos == vPosDest && Dest1or2 == true )
    {       
        Dest1or2 = false;
    }
    else if (vCurrentPos == vPosTrans && Dest1or2 == false)
    {
        Dest1or2 = true;
    }
    if(Dest1or2)
    vCurrentPos = glm::mix(vCurrentPos, vPosDest, currentTime * 0.01f);
    else 
    vCurrentPos = glm::mix(vCurrentPos, vPosTrans, currentTime*0.01f);
 
    //transform = glm::translate(transform, vCurrentPos);
    //transform = glm::translate(transform, glm::vec3(-0.51f, -0.51f, 0.0f));
    //transform = glm::rotate(transform, ((GLfloat)currentTime / 100) * 90.0f, glm::vec3(0.0f, 0.0f, 1.0f));
 
    // RTS
    GLuint transformLoc = glGetUniformLocation(program, "transform");
    glUniformMatrix4fv(transformLoc, 1, GL_FALSE, glm::value_ptr(transform));
 
    GLint modelLoc = glGetUniformLocation(program, "model");
    GLint viewLoc = glGetUniformLocation(program, "view");
    GLint projLoc = glGetUniformLocation(program, "projection");
 
    // Pass them to the shaders
    glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
    glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(camera->getViewMatrix()));
    glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(camera->getProjectionMatrix()));
    //glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
    //glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));
 
 
    glutPostRedisplay();
}
 
void keyboard(unsigned char key, int x, int y) {
    keyState[key] = BUTTON_DOWN;
 
    //printf("key pressed: %d \n", key);
}
 
void keyboard_up(unsigned char key, int x, int y) {
    keyState[key] = BUTTON_UP;
}
 
int main(int argc, char **argv){
 
    // init glut
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
 
    glutInitWindowPosition(300, 200);
    glutInitWindowSize(800, 600);
    glutCreateWindow("QUAD EBO");
 
    //init GLEW
    glewInit();
 
    init();
 
    //clear
    glClearColor(1.0, 0.0, 0.0, 1.0);//clear red
 
    // register callbacks
    glutDisplayFunc(render);
 
    glutKeyboardFunc(keyboard);
    glutKeyboardUpFunc(keyboard_up);
 
    glutIdleFunc(update);
 
    glutMainLoop();
 
    return 0;
}
 
 
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#include "Dependencies\glew\glew.h"
#include "Dependencies\freeglut\freeglut.h"
#include "Dependencies\soil\SOIL.h"

#include "glm/glm.hpp"
#include "glm/gtc/matrix_transform.hpp"
#include "glm/gtc/type_ptr.hpp"

#include <iostream>

#include "ShaderLoader.h";
#include "Camera.h"

#define BUTTON_UP   0
#define BUTTON_DOWN 1

GLuint program;
GLuint vao, vbo, ebo;
GLuint texture, texture2;

unsigned char keyState[255];


glm::vec3 vPosTrans = glm::vec3(-0.50f, -0.50f, 0.0f);//source
glm::vec3 vPosInit = vPosTrans;
glm::vec3 vPosDest = glm::vec3(0.50f, 0.50f, 0.0f);//destination
glm::vec3 vCurrentPos = vPosTrans;

bool Dest1or2 = true;

const GLfloat WIDTH = 800.0f, HEIGHT = 600.0f;

Camera* camera;

void init(){
    camera = new Camera(180.0f, WIDTH, HEIGHT, 0.0f, 100.0f);

    ShaderLoader shaderLoader;
    program = shaderLoader.CreateProgram("CoordSystem_Texture_QUAD.vs", "CoordSystem_Texture_QUAD.fs");

    glEnable(GL_DEPTH_TEST);

    glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);

    // Set up vertex data (and buffer(s)) and attribute pointers
    GLfloat vertices[] = {

        //position              //color                 //texture coord   //Normals
        -1.01f, -1.01f, -1.01f, 1.0f, 0.0f, 0.0f,       0.0f, 1.0f,
        -1.01f, 1.01f, -1.01f,      0.0f, 1.0f, -0.0f,      0.0f, 0.0f,
        1.01f, 1.01f, -1.01f,       1.0f, 0.0f, -0.0f,      1.0f, 0.0f,
        1.01f, -1.01f, -1.01f,      0.0f, 1.0f,  1.0f,      1.0f, 1.0f,

        // Fill in the back face vertex data.
        -1.01f, -1.01f, 1.01f,      0.0f, 1.0f, 1.0f,       1.0f, 1.0f,
        1.01f, -1.01f, 1.01f,       1.0f, 0.0f, 1.0f,       0.0f, 1.0f,
        1.01f, 1.01f, 1.01f,        1.0f, 0.0f, 1.0f,       0.0f, 0.0f,
        -1.01f, 1.01f, 1.01f,       1.0f, 1.0f, 0.0f,       1.0f, 0.0f,

        // Fill in the top face vertex data.
        -1.01f, 1.01f, -1.01f,      0.0f, 1.0f, 0.0f,       0.0f, 1.0f,
        -1.01f, 1.01f, 1.01f,       1.0f, 0.0f, 1.0f,       0.0f, 0.0f,
        1.01f, 1.01f, 1.01f,        0.0f, 1.0f, 1.0f,       1.0f, 0.0f,
        1.01f, 1.01f, -1.01f,       1.0f, 1.0f, 0.0f,       1.0f, 1.0f,

        // Fill in the bottom face vertex data.
        -1.01f, -1.01f, -1.01f, 1.0f,  1.0f, 0.0f,      1.0f, 1.0f,
        1.01f, -1.01f, -1.01f,      0.0f,  1.0f, 1.0f,      0.0f, 1.0f,
        1.01f, -1.01f, 1.01f,       0.0f,  1.0f, 0.0f,      0.0f, 0.0f,
        -1.01f, -1.01f, 1.01f,      1.0f,  1.0f, 0.0f,      1.0f, 0.0f,

        // Fill in the left face vertex data.
        -1.01f, -1.01f, 1.01f,       1.0f, 1.0f, 0.0f,      0.0f, 1.0f,
        -1.01f, 1.01f, 1.01f,        1.0f, 0.0f, 1.0f,      0.0f, 0.0f,
        -1.01f, 1.01f, -1.01f,       1.0f, 0.0f, 1.0f,      1.0f, 0.0f,
        -1.01f, -1.01f, -1.01f,  1.0f, 1.0f, 0.0f,      1.0f, 1.0f,

        // Fill in the right face vertex data.
        1.01f, -1.01f, -1.01f,      1.0f, 1.0f, 0.0f,       0.0f, 1.0f,
        1.01f, 1.01f, -1.01f,       0.0f, 1.0f, 1.0f,       0.0f, 0.0f,
        1.01f, 1.01f, 1.01f,        1.0f, 0.0f, 1.0f,       1.0f, 0.0f,
        1.01f, -1.01f, 1.01f,       0.0f, 1.0f, 1.0f,       1.0f, 1.0f,
    };

    GLuint indices[] = {
        // front
        0, 1, 2,
        0, 2, 3,
        // top
        4, 5, 6,
        4, 6, 7,
        // back
        8, 9, 10,
        8, 10, 11,
        // bottom
        12, 13, 14,
        12, 14, 15,
        // left
        16, 17, 18,
        16, 18, 19,
        // right
        20, 21, 22,
        20, 22, 23,
    };

    //** VAO **
    // Generate vertex arrow object
    glGenVertexArrays(1, &vao);
    // Bind the Vertex Array Object to openGl context
    glBindVertexArray(vao);//otherwise glVertexAttribPointer

    //** VBO **
    // Then bind and set vertex buffer(s).
    // First paramter is how many buffers we have to create
    glGenBuffers(1, &vbo);

    // bind VBO to binding point, here it is GL_ARRAY_BUFFER
    // there are other binding points
    glBindBuffer(GL_ARRAY_BUFFER, vbo);//bind to context
    glBufferData(GL_ARRAY_BUFFER,
        sizeof(vertices),// GPU need to know how much memory needs to be allocated
        vertices,//copy data to GPU
        GL_STATIC_DRAW);// How to use the buffer - buffer is created and modified once

    //** EBO **
    glGenBuffers(1, &ebo);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER,
        sizeof(indices),
        indices,
        GL_STATIC_DRAW);


    // ** Attributes **

    //** Vertex Attribute **
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)0);
    glEnableVertexAttribArray(0);

    //** Color Attribute **
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
    glEnableVertexAttribArray(1);

    //** TexCoord attribute **
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(6 * sizeof(GLfloat)));
    glEnableVertexAttribArray(2);

    // It's always a good thing to unbind any buffer/array to prevent strange bugs
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindVertexArray(0);

    //** Load and bind texture 1 
    //--------------------------
    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);


    //** loadImage and create texture
    // Load image, create texture and generate mipmaps
    int width, height;
    unsigned char* image = SOIL_load_image("wall.jpg", &width, &height, 0, SOIL_LOAD_RGB);
    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);
    glBindTexture(GL_TEXTURE_2D, 0);


    // ** Load and Bind Texture 2
    //---------------------------
    glGenTextures(1, &texture2);
    glBindTexture(GL_TEXTURE_2D, texture2);


    //** loadImage and create texture
    // Load image, create texture and generate mipmaps
    unsigned char* image2 = SOIL_load_image("awesomeface.png", &width, &height, 0, SOIL_LOAD_RGB);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image2);
    glGenerateMipmap(GL_TEXTURE_2D);
    SOIL_free_image_data(image2);
    glBindTexture(GL_TEXTURE_2D, 0);


    // Set texture wrapping to GL_REPEAT (usually basic wrapping method)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    // Set texture filtering parameters
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

}

void render(){

    glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    // Draw our first triangle
    glUseProgram(program);

    //bind 
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texture);
    glUniform1i(glGetUniformLocation(program, "Texture"), 0);

    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, texture2);
    glUniform1i(glGetUniformLocation(program, "Texture2"), 1);

    glBindVertexArray(vao);

    // Draw Elements intead of vertex array 
    glDrawArrays(GL_QUADS, 0, 24);
    //glDrawElements(GL_TRIANGLES, 24, GL_UNSIGNED_INT, 0);
    glBindVertexArray(0);

    glutSwapBuffers();
}

void update(){
    GLfloat cameraSpeed = 0.05f;
    camera->setCameraSpeed(cameraSpeed);

    //currentTime uniform
    GLfloat currentTime = glutGet(GLUT_ELAPSED_TIME);
    currentTime = currentTime / 1000;
    GLint currentTimeLocation = glGetUniformLocation(program, "currentTime");
    glUniform1f(currentTimeLocation, currentTime);

    //transforms
    glm::mat4 transform = glm::mat4(1.0f);
    glm::vec3 vScaleVec = glm::vec3(0.51f, 0.51f, 0.0f);

    glm::mat4 model = glm::mat4(1.0);

    if (keyState[(unsigned char)'w'] == BUTTON_DOWN) {
        camera->moveForward();
        std::cout << "e";
    }
    if (keyState[(unsigned char)'s'] == BUTTON_DOWN) {
        camera->moveBack();
        std::cout << "A";
    }

    camera->Update();

    //glm::mat4 projection = glm::perspective(45.0f, (GLfloat)WIDTH / (GLfloat)HEIGHT, 0.1f, 100.0f);
    glm::mat4 projection = camera->getProjectionMatrix();

    glm::mat4 view = glm::lookAt(camera->getCameraPos(), camera->getCameraPos() + camera->getCameraFront(), camera->getCameraUp());

    //glm::mat4 view = glm::lookAt(glm::vec3(1, 1, 0), glm::vec3(0, 1, 0), glm::vec3(0, 0, 1));

    GLfloat radius = 3.5f;
    GLfloat camX = sin(currentTime) * radius;
    GLfloat camZ = cos(currentTime) * radius;
     
    //glm::mat4 view = glm::lookAt(
    //     glm::vec3(camX, 0.0, camZ),
    //     glm::vec3(0.0, 0.0, 0.0),
    //     glm::vec3(0.0, 1.0, 0.0));

    transform = glm::scale(transform, vScaleVec);
    glm::vec3(0.65f, 0.65f, 0.65f);
    //transform = glm::rotate(transform, 90.0f, glm::vec3(0.0, 0.0, 1.0));
    if (vCurrentPos == vPosDest && Dest1or2 == true )
    {       
        Dest1or2 = false;
    }
    else if (vCurrentPos == vPosTrans && Dest1or2 == false)
    {
        Dest1or2 = true;
    }
    if(Dest1or2)
    vCurrentPos = glm::mix(vCurrentPos, vPosDest, currentTime * 0.01f);
    else 
    vCurrentPos = glm::mix(vCurrentPos, vPosTrans, currentTime*0.01f);
    
    //transform = glm::translate(transform, vCurrentPos);
    //transform = glm::translate(transform, glm::vec3(-0.51f, -0.51f, 0.0f));
    //transform = glm::rotate(transform, ((GLfloat)currentTime / 100) * 90.0f, glm::vec3(0.0f, 0.0f, 1.0f));

    // RTS
    GLuint transformLoc = glGetUniformLocation(program, "transform");
    glUniformMatrix4fv(transformLoc, 1, GL_FALSE, glm::value_ptr(transform));

    GLint modelLoc = glGetUniformLocation(program, "model");
    GLint viewLoc = glGetUniformLocation(program, "view");
    GLint projLoc = glGetUniformLocation(program, "projection");

    // Pass them to the shaders
    glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
    glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(camera->getViewMatrix()));
    glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(camera->getProjectionMatrix()));
    //glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
    //glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));


    glutPostRedisplay();
}

void keyboard(unsigned char key, int x, int y) {
    keyState[key] = BUTTON_DOWN;

    //printf("key pressed: %d \n", key);
}

void keyboard_up(unsigned char key, int x, int y) {
    keyState[key] = BUTTON_UP;
}

int main(int argc, char **argv){

    // init glut
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);

    glutInitWindowPosition(300, 200);
    glutInitWindowSize(800, 600);
    glutCreateWindow("QUAD EBO");

    //init GLEW
    glewInit();

    init();

    //clear
    glClearColor(1.0, 0.0, 0.0, 1.0);//clear red

    // register callbacks
    glutDisplayFunc(render);

    glutKeyboardFunc(keyboard);
    glutKeyboardUpFunc(keyboard_up);

    glutIdleFunc(update);

    glutMainLoop();

    return 0;
}

片段着色器：

#version 430 core

in vec3 outColor;
in vec2 TexCoord;

out vec4 color;

uniform sampler2D Texture;
uniform sampler2D Texture2;

uniform float currentTime;

void main()
{
    //vec3 colorTemp = outColor * abs(sin(currentTime));
    //color = vec4(colorTemp, 1.0f) ;
    //color = texture(ourTexture, TexCoord) * vec4(outColor, 1.0f) * abs(sin(currentTime))  ;
    
    color = mix(texture(Texture, TexCoord), texture(Texture2, TexCoord), 0.2) * vec4(outColor, 1.0f) * abs(sin(currentTime));
}

顶点着色器：

#version 430 core
layout (location = 0) in vec3 position;
layout (location = 1) in vec3 color;
layout (location = 2) in vec2 texCoord;

out vec3 outColor;
out vec2 TexCoord;
 
uniform mat4 transform;
 
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

void main(void)
{
    gl_Position = projection * view * model * transform * vec4(position, 1.0);
    outColor = color;
    TexCoord = vec2(texCoord.x, 1.0 - texCoord.y);
}

【问题讨论】：

  • 您需要将代码添加到问题中。到场外资源的链接是不够的。与外部资源的链接往往会中断，并且该资源将来可能不再可用。请阅读How to create a Minimal, Reproducible Example 和How do I ask a good question?。
  • glm::perspective 的单位是弧度而不是度数。使用glm::radians(45.0f) 将度数转换为弧度。
  • 试试glm::mat4 projection = glm::perspective(glm::radians(45.0f), (GLfloat)WIDTH / (GLfloat)HEIGHT, 0.1f, 100.0f);和glm::mat4 view = glm::lookAt(glm::vec3(10, 10, 10), glm::vec3(0, 0, 0), glm::vec3(0, 0, 1));
  • 这些都不起作用，仍然只是渲染了一个二维正方形

标签： c++ opengl glut glm-math


【解决方案1】：

如果我注释掉该函数，它会将所有顶点呈现为好像 z 值都是 0

嗯，那是因为......他们是：

glm::vec3 vScaleVec = glm::vec3(0.51f, 0.51f, 0.0f);
[...]
transform = glm::scale(transform, vScaleVec);
[...]
gl_Position = projection * view * model * transform * vec4(position, 1.0);

您使用z=0 进行缩放，这意味着您将所有顶点移动到 z = 0 平面中。所以在你的第一个转换步骤之后它已经是平坦的（这也意味着transform 是一个奇异矩阵，第三行和第三列全为零）。您在代码中注释掉的附加变换步骤，以及在着色器中应用的所有其他矩阵，都不会改变任何这些，无论您预先或发布什么其他矩阵，对象仍然是平面-乘以它，他们只是移动那架飞机。

我不知道你想要多大的缩放比例，但是按 0 缩放几乎从来都不是一个好主意，而 1 是缩放操作的中性元素。

另外，为什么在着色器中有 model 和 transform 作为单独的矩阵？在 3d 计算机图形学中，模型矩阵通常包含将对象从其自己的本地模型空间映射到世界空间所需的所有转换。即使您需要在内部跟踪转换的不同部分，通常在 gpu 上的实际渲染过程中也不需要这些，并且应该在 CPU 上将所有这些相乘，并将累积的转换作为model 矩阵发送到着色器。

【讨论】：

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