Question

我应该在屏幕上显示两个正方形，但是当我运行它时，我看到的只是一个虚无的屏幕。

#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <fstream>
#include <iostream>
#include <sstream>
#include <string>




struct Shaderprogramsource
{
std::string VertexSouce;
std::string FragmentSource;
};

static Shaderprogramsource Parseshader(const std::string& filepath)
{
std::ifstream stream(filepath);

enum class Shadertype
{
    VERTEX = 0,
    FRAGMENT = 1,
    NONE = 5
};

std::string line;
std::stringstream ss[3];

Shadertype type = Shadertype::NONE;

while (getline(stream, line))
{
    if (line.find("#shader") != std::string::npos)
    {
        if (line.find("vertex") != std::string::npos)
            type = Shadertype::VERTEX;

        else if (line.find("fragment") != std::string::npos)
            type = Shadertype::FRAGMENT;
    }
    else
    {
        ss[(int)type] << line << "\n";
    }
}

return Shaderprogramsource{ ss[0].str(), ss[1].str() };
}

static int CompileShader(unsigned int type, const std::string& Source)
{
unsigned int id = glCreateShader(type);
const char* src = Source.c_str();
glShaderSource(id, 1, &src, nullptr);
glCompileShader(id);

int result;
glGetShaderiv(id, GL_COMPILE_STATUS, &result);

if (result == GL_FALSE)
{
    int length;
    glGetShaderiv(id, GL_INFO_LOG_LENGTH, &length);

    char* message = (char*)alloca(length * sizeof(char));
    glGetShaderInfoLog(id, length, &length, message);

    std::cout << message;

    return 0;
}

return id;
}

static unsigned int CreateShader(
const std::string& Vertexshader,
const std::string& Fragmentshader)
{
unsigned int program = glCreateProgram();
unsigned int vertex = CompileShader(GL_VERTEX_SHADER, Vertexshader);
unsigned int fragment = CompileShader(GL_FRAGMENT_SHADER, Fragmentshader);

glAttachShader(program, vertex);
glAttachShader(program, fragment);

glLinkProgram(program);
glValidateProgram(program);

return program;
}

int main(void)
{
GLFWwindow* window;

/* Initialize the library */
if (!glfwInit())
    return -1;

glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);






/* Create a windowed mode window and its OpenGL context */
window = glfwCreateWindow(800, 800, "Hello World", NULL, NULL);
if (!window)
{
    glfwTerminate();
    return -1;
}

/* Make the window's context current */
glfwMakeContextCurrent(window);

if (GLEW_OK == glewInit())
{
}

float vertices[] = { -0.1, -0.1,
                      0.1, -0.1, 
                      0.1, 0.1, 
                     -0.1, 0.1 };



float vertices2[] = { -0.1,0.1,
                      0.1, 0.1,
                      0.1, 0.3,
                     -0.1, 0.3 };


unsigned int indices[] = {

    0, 1, 2,
    2, 3, 0


};

unsigned int vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);

unsigned int vao2;
glGenVertexArrays(1, &vao2);
glBindVertexArray(vao2);


unsigned int buffer1;

unsigned int vbo;

glGenBuffers(1, &buffer1);
glBindBuffer(GL_ARRAY_BUFFER, buffer1);
glBufferData(GL_ARRAY_BUFFER, 4 * 2 * sizeof(float), vertices, GL_STATIC_DRAW);

glEnableVertexAttribArray(0);

glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0);

glEnableVertexAttribArray(1);

glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0);



glGenBuffers(1, &vbo);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vbo);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, 6 * sizeof(unsigned int), indices, GL_STATIC_DRAW);





Shaderprogramsource source = Parseshader("res/shaders/Basic.Shader");

unsigned int shader =
    CreateShader(source.VertexSouce, source.FragmentSource);




glUseProgram(shader);


int location = glGetUniformLocation(shader, "Color_u");
if (location > -1) {
    glUniform4f(location, 0.8f, 0.0f, 0.0f, 1.0f);

}



std::cout << source.VertexSouce;

glUseProgram(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);

/* Loop until the user closes the window */
while (!glfwWindowShouldClose(window))
{
    /* Render here */

    glClear(GL_COLOR_BUFFER_BIT);

    glUseProgram(shader);
    glBindBuffer(GL_ARRAY_BUFFER, vao);
    glBindBuffer(GL_ARRAY_BUFFER, vao2);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vbo);


    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0);

    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0);

    glEnableVertexAttribArray(0);

    glEnableVertexAttribArray(1);

    glUseProgram(shader);
    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr);

    /* Swap front and back buffers */
    glfwSwapBuffers(window);

    /* Poll for and process events */
    glfwPollEvents();
}

glDeleteProgram(shader);

glfwTerminate();
return 0;
}

着色器：

#shader vertex
#version 330 core

layout(location = 0) in vec3 position;



void main()
{
gl_Position = vec4(position.x, position.y, position.z, 1.0);
};

#shader fragment
#version 330 core

layout(location = 0) out vec4 color;

uniform vec4 Color_u;

void main()
{
color = Color_u;
};

Answer 1

各种各样的“ wonk-a-donk”：

var userInput = prompt('Which fruit would you like?');
var fruitList = ["banana", 'strawberries', "mango"];
let newItem = false;
for (let i = 0; i < fruitList.length; i++) {
  if (userInput == fruitList[i]) {
    newItem = false;
    alert("Sorry, we are out of " + userInput);
  } else {
    newItem = true;
  }
}
if (newItem) {

  let userFruit = document.createElement('li');
  userFruit.innerHTML = userInput
  let fruits = document.getElementById('list');
  fruits.appendChild(userFruit);
}

<ul id="list"> </ul>会中断，因为Parseshader()设置为5，并且#shader索引+赋值将执行在3元素NONE数组的末尾。将ss[(int)type]放到ss。
着色器（NONE）中只有一个顶点属性，但您正在尝试设置2。
这根本不是VAO的工作方式。 VAO从来没有成为0的有效参数。插入，绑定VAO，然后设置顶点属性绑定/布局：
```
1
```
然后，当您要绘制时，您可以重新绑定VAO并立即绘制，跳过所有glBindBuffer() / unsigned int vao1 = 0; glGenVertexArrays(1, &vao1); glBindVertexArray(vao1); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo); glBindBuffer(GL_ARRAY_BUFFER, buffer1); glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0); glEnableVertexAttribArray(0); / glBindBuffer()设置。

一起：

glVertexAttribPointer()

多个对象无法渲染？

1 个答案: