c++ - 无法在 OpenGL 中获取矩形的 3D View

Question

我正在学习本教程。 https://learnopengl.com/#!Getting-started/Coordinate-Systems - 副主题进入 3D 部分我无法获得仅输出空白屏幕。

这是我的代码:

#define STB_IMAGE_IMPLEMENTATION
#include <stb_image.h>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include "shaders.h"
#include "camera.h"
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

GLFWwindow* window;
GLuint VBO, VAO,EBO;
unsigned int texture;
const unsigned int screenwidth = 800;
const unsigned int screenheight = 600;
float vertices[] =
{
    0.5f,  0.5f, 0.0f,    1.0f, 1.0f, 
    0.5f, -0.5f, 0.0f,    1.0f, 0.0f, 
    -0.5f, -0.5f, 0.0f,   0.0f, 0.0f,
    -0.5f,  0.5f, 0.0f,   0.0f, 1.0f  
};
unsigned int indices[] = 
{
    0, 1, 3,
    1, 2, 3  
};
void glfwinitializer()
{
    glfwInit();
    window = glfwCreateWindow(screenwidth, screenheight, "Question 2 : Camera Space", NULL, NULL);
    if (window == NULL)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
    }
    glfwMakeContextCurrent(window);

    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
    }
    glEnable(GL_DEPTH_TEST);
}
void initializeVertex()
{
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);
    glBindVertexArray(VAO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindVertexArray(0);
}
void initializeTexture()
{
    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, 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);
    int width, height, nrChannels;
    unsigned char *data = stbi_load("text.jpg", &width, &height, &nrChannels, 0);
    if (data)
    {
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
        glGenerateMipmap(GL_TEXTURE_2D);
    }
    else
    {
        std::cout << "Failed to load texture" << std::endl;
    }
    stbi_image_free(data);

}
int main()
{
    glfwinitializer();
    Shader ourShader("vertexshader.vs", "fragmentshader.fs");
    initializeVertex();
    initializeTexture();
    glm::mat4 projection(1);
    projection = glm::perspective(glm::radians(45.0f), (float)screenwidth / (float)screenheight, 0.1f, 100.0f);
    ourShader.setMat4("projection", projection);
    while (!glfwWindowShouldClose(window))
    {
        glClearColor(0.2f, 0.3f, 0.3f, 1.0f); 
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glBindTexture(GL_TEXTURE_2D, texture);
        ourShader.use();
        glm::mat4 model(1);
        model = glm::rotate(model, glm::radians(-55.f), glm::vec3(1.0f, 0.0f, 0.0f));
        ourShader.setMat4("model", model);
        glm::mat4 view(1);
        view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));
        ourShader.setMat4("view", view);
        glBindVertexArray(VAO);
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);
    glDeleteBuffers(1, &EBO);
    glfwTerminate();
    return 0;
}

我的顶点着色器是:

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec2 aTexCoord;

out vec2 TexCoord;

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

void main()
{
    gl_Position = projection*view*model*vec4(aPos, 1.0);
    TexCoord = vec2(aTexCoord.x,aTexCoord.y);
}

尝试实现此代码。我得到空白输出。 Output Image Here : No Rectangle如果我注释三种模式、 View 和投影矩阵并从顶点着色器文件中删除。 .我能够在屏幕上看到矩形。 Output Image Here: Rectangle

我还有一个问题

glm::mat4 model(1);
glm::mat4 view(1);
glm::mat4 projection(1);

仅包含值 1。当我尝试评论以下行时

//model = glm::rotate(model, glm::radians(-55.f), glm::vec3(1.0f, 0.0f, 0.0f));
//view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));
//projection = glm::perspective(glm::radians(45.0f), (float)screenwidth / (float)screenheight, 0.1f, 100.0f);

并在不改变的情况下运行程序

gl_position = projection*view*model*vec4(aPos, 1.0);

黑屏

Answer 1

glUniformMatrix4fv为当前程序对象指定统一变量的值。

这意味着 glUseProgram必须在之前完成 glUniformMatrix4fv .

但是你打电话

ourShader.setMat4("projection", projection);

之前

ourShader.use();

所以统一变量 mat4 projection; 永远不会被设置。

像这样改变你的代码:

ourShader.use();
ourShader.setMat4("projection", projection);

我总的来说你的代码很好，除了你应该为 mipmap 使用缩小函数:

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);