c++ - 三角形不出现在OpenGL中？

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我可以使Opengl三角形出现。

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

const char* vertexShaderSource = "#version 330 core\n"
"layout (location = 0) in vec3 aPos;\n"
"void main()\n"
"{\n"
"   gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
"}\0";
const char* fragmentShaderSource = "#version 330 core\n"
"out vec4 FragColor;\n"
"void main()\n"
"{\n"
"   FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
"}\n\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); }
}

int main()
{


    glewExperimental = GL_TRUE;
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR,3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR,3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    GLFWwindow* window{ glfwCreateWindow(800,600,"Opengl",NULL,NULL) };

    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);


    glfwMakeContextCurrent(window);


     GLenum err = glewInit();
   if (glewInit() != GLEW_OK) { std::cout << glewGetErrorString(err); return -1; }







    int vertexShader;
    vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);

    int fragmentShader;
    fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader,1,&fragmentShaderSource,NULL);
    glCompileShader(fragmentShader);



    int shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram,vertexShader);
    glAttachShader(shaderProgram,fragmentShader);
    glLinkProgram(shaderProgram);


    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);

    float triangle[]{ -0.5f,-0.5f,0.0f,
                      0.5f,-0.5f,0.0,
                      0.0f,-0.5f,0.0f };


    unsigned int VAO,buffer;
    glGenVertexArrays(1, &VAO);
    glBindVertexArray(VAO);


    glGenBuffers(1, &buffer);
    glBindBuffer(GL_ARRAY_BUFFER, buffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(triangle), triangle, GL_STATIC_DRAW);


    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3*sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);

    glBindBuffer(GL_ARRAY_BUFFER,0);
    glBindVertexArray(0);


    if (window == NULL) {
        std::cout << "Window is null";
        glfwTerminate();
        return -1;
    }





    while (!glfwWindowShouldClose(window))
    {


        processInput(window);

        glClearColor(0.2f, 0.2f, 0.2f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        glUseProgram(shaderProgram);
        glBindVertexArray(VAO);
        glDrawArrays(GL_TRIANGLES,0,3);


        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    glfwTerminate();



    return 0;
}

最佳答案

您所有的三角形顶点均为colinear，从而形成一个degenerate三角形

将第三个点的y坐标碰撞到0.5对我来说有效:

  float triangle[]
  {
    -0.5f, -0.5f, 0.0f,
     0.5f, -0.5f, 0.0f,
     0.0f,  0.5f, 0.0f,
  };

全部一起:

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

const char* vertexShaderSource = 
    "#version 330 core\n"
    "layout (location = 0) in vec3 aPos;\n"
    "void main()\n"
    "{\n"
    "   gl_Position = vec4(aPos.x, aPos.y, "
    "aPos.z, 1.0);\n"
    "}\0";
const char* fragmentShaderSource =
    "#version 330 core\n"
    "out vec4 FragColor;\n"
    "void main()\n"
    "{\n"
    "   FragColor = vec4(1.0f, 0.5f, 0.2f, "
    "1.0f);\n"
    "}\n\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 );
    }
}

int main()
{
    glewExperimental = GL_TRUE;
    glfwInit();
    glfwWindowHint( GLFW_CONTEXT_VERSION_MAJOR, 3 );
    glfwWindowHint( GLFW_CONTEXT_VERSION_MINOR, 3 );
    glfwWindowHint( GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE );
    GLFWwindow* window{ glfwCreateWindow( 800, 600, "Opengl", NULL, NULL ) };

    glfwSetFramebufferSizeCallback( window, framebuffer_size_callback );

    glfwMakeContextCurrent( window );

    GLenum err = glewInit();
    if( glewInit() != GLEW_OK )
    {
        std::cout << glewGetErrorString( err );
        return -1;
    }

    int vertexShader;
    vertexShader = glCreateShader( GL_VERTEX_SHADER );
    glShaderSource( vertexShader, 1, &vertexShaderSource, NULL );
    glCompileShader( vertexShader );

    int fragmentShader;
    fragmentShader = glCreateShader( GL_FRAGMENT_SHADER );
    glShaderSource( fragmentShader, 1, &fragmentShaderSource, NULL );
    glCompileShader( fragmentShader );

    int shaderProgram = glCreateProgram();
    glAttachShader( shaderProgram, vertexShader );
    glAttachShader( shaderProgram, fragmentShader );
    glLinkProgram( shaderProgram );

    glDeleteShader( vertexShader );
    glDeleteShader( fragmentShader );

    float triangle[]{
        -0.5f, -0.5f, 0.0f, 0.5f, -0.5f, 0.0f, 0.0f, 0.5f, 0.0f,
    };

    unsigned int VAO, buffer;
    glGenVertexArrays( 1, &VAO );
    glBindVertexArray( VAO );

    glGenBuffers( 1, &buffer );
    glBindBuffer( GL_ARRAY_BUFFER, buffer );
    glBufferData(
        GL_ARRAY_BUFFER, sizeof( triangle ), triangle, GL_STATIC_DRAW );

    glVertexAttribPointer(
        0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof( float ), (void*)0 );
    glEnableVertexAttribArray( 0 );

    glBindBuffer( GL_ARRAY_BUFFER, 0 );
    glBindVertexArray( 0 );

    if( window == NULL )
    {
        std::cout << "Window is null";
        glfwTerminate();
        return -1;
    }

    while( !glfwWindowShouldClose( window ) )
    {
        processInput( window );

        glClearColor( 0.2f, 0.2f, 0.2f, 1.0f );
        glClear( GL_COLOR_BUFFER_BIT );

        glUseProgram( shaderProgram );
        glBindVertexArray( VAO );
        glDrawArrays( GL_TRIANGLES, 0, 3 );

        glfwSwapBuffers( window );
        glfwPollEvents();
    }

    glfwTerminate();

    return 0;
}

关于c++ - 三角形不出现在OpenGL中？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/61967621/

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