无法在屏幕上绘制正方形(相同的宽度和高度)

Question

我不能画一个高度和宽度相同的物体。我本来想做一些更复杂的事情，但我已经尽可能地把它分解了：

我有一个分辨率为600x600px的窗口和以下顶点和片段着色器：

顶点着色器

#version 330 core

layout (location = 0) in vec3 aPos;
void main()
{
    gl_Position =  vec4(aPos, 1.0f);
}

片段着色器

#version 330 core
out vec4 FragColor;
void main()
    {
        FragColor = vec4(1.0f,1.0f,1.0f,1.0f);
    }

我收到的输出如下：

​

下面是我用来绘制正方形的代码：

#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include "shader.h"
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include "Object.h"

int width = 600;
int height = 600;

int main()
{
//window creation -----------------------------------------------------------
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    glfwWindowHint(GLFW_SAMPLES, 16);
    GLFWwindow* window = glfwCreateWindow(width, height, "Mumel", NULL, NULL);

    glfwMakeContextCurrent(window);

    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Error during GLAD initialization" << std::endl;
        glfwTerminate();
        return -1;
    }

    glViewport(0, 0, width, height);
//----------------------------------------------------------------------
    Shader sh("./shader/vShader.vSh", "./shader/fShader.fSh");

    Circle * circle = new Circle(0.5); //is explained later in the post

    while (!glfwWindowShouldClose(window))
    {
        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        sh.use();
        circle->draw();

        glfwSwapBuffers(window);
        glfwPollEvents();
    }
}

最后但并非最不重要的是，我的“循环”(它应该是一个循环，但是一个方块更易于调试)是由以下代码创建的：

#ifndef OBJECT_H
#define OBJECT_H

#include <glad/glad.h>
#include <iostream>
#include "shader.h"
#include <vector>


class Circle
{
public:
    static const int size = 6; 

    Circle()
    {
        std::vector<float> vertexData(3 * size); 
        // center 
        vertexData.at(0) = 0.0f;
        vertexData.at(1) = 0.0f;
        vertexData.at(2) = 0.0f;

        vertexData.at(3) = 0.5f;
        vertexData.at(5) = 0.0f;
        vertexData.at(4) = -0.5f;

        vertexData.at(6) = -0.5f;
        vertexData.at(8) = 0.0f;
        vertexData.at(7) = -0.5f;

        vertexData.at(9) = -0.5f;
        vertexData.at(11) = 0.0f;
        vertexData.at(10) = 0.5f;

        vertexData.at(12) = 0.5f;
        vertexData.at(14) = 0.0f;
        vertexData.at(13) = 0.5f;

        vertexData.at(15) = 0.5f;
        vertexData.at(17) = 0.0f;
        vertexData.at(16) = -0.5f;


        glGenBuffers(1, &VBO);
        glGenVertexArrays(1, &VAO);
        glBindVertexArray(VAO);

        float * dataArr = vertexData.data(); //The GLSL shader needs a C Array, this returns the pointer to the first array object used by std::vector
        int dataSize = vertexData.size();

        glBindBuffer(GL_ARRAY_BUFFER, VBO);
        glBufferData(GL_ARRAY_BUFFER, dataSize * sizeof(float), dataArr, GL_STATIC_DRAW);

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

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

    void draw()
    {
        glBindVertexArray(VAO);
        glDrawArrays(GL_TRIANGLE_FAN, 0, 3 * (size - 2));
        glBindVertexArray(0);
    }
private:
    unsigned int VBO, VAO;

};

#endif

Answer 1

对我来说很好：

​

系统/构建信息：

• Windows 10
• GLFW 3.3
• 监视器设置为1920x1200
• 100% GUI缩放

代码：

#include <glad/glad.h>
#define GLFW_INCLUDE_NONE
#include <GLFW/glfw3.h>
#include <glm/glm.hpp>
#include <vector>
#include <iostream>

void CheckStatus( GLuint obj, bool isShader )
{
    GLint status = GL_FALSE, log[ 1 << 11 ] = { 0 };
    ( isShader ? glGetShaderiv : glGetProgramiv )( obj, isShader ? GL_COMPILE_STATUS : GL_LINK_STATUS, &status );
    if( status == GL_TRUE ) return;
    ( isShader ? glGetShaderInfoLog : glGetProgramInfoLog )( obj, sizeof( log ), NULL, (GLchar*)log );
    std::cerr << (GLchar*)log << "\n";
    std::exit( EXIT_FAILURE );
}

void AttachShader( GLuint program, GLenum type, const char* src )
{
    GLuint shader = glCreateShader( type );
    glShaderSource( shader, 1, &src, NULL );
    glCompileShader( shader );
    CheckStatus( shader, true );
    glAttachShader( program, shader );
    glDeleteShader( shader );
}

const char* const vert = 1 + R"GLSL(
#version 330 core
layout (location = 0) in vec3 aPos;
void main()
{
    gl_Position =  vec4(aPos, 1.0f);
}
)GLSL";

const char* const frag = 1 + R"GLSL(
#version 330 core
out vec4 FragColor;
void main()
{
    FragColor = vec4(1.0f,1.0f,1.0f,1.0f);
}
)GLSL";

class Circle
{
public:
    static const int size = 6; 

    Circle()
    {
        std::vector<float> vertexData(3 * size); 
        // center 
        vertexData.at(0) = 0.0f;
        vertexData.at(1) = 0.0f;
        vertexData.at(2) = 0.0f;

        vertexData.at(3) = 0.5f;
        vertexData.at(5) = 0.0f;
        vertexData.at(4) = -0.5f;

        vertexData.at(6) = -0.5f;
        vertexData.at(8) = 0.0f;
        vertexData.at(7) = -0.5f;

        vertexData.at(9) = -0.5f;
        vertexData.at(11) = 0.0f;
        vertexData.at(10) = 0.5f;

        vertexData.at(12) = 0.5f;
        vertexData.at(14) = 0.0f;
        vertexData.at(13) = 0.5f;

        vertexData.at(15) = 0.5f;
        vertexData.at(17) = 0.0f;
        vertexData.at(16) = -0.5f;

        glGenBuffers(1, &VBO);
        glGenVertexArrays(1, &VAO);
        glBindVertexArray(VAO);

        float * dataArr = vertexData.data(); //The GLSL shader needs a C Array, this returns the pointer to the first array object used by std::vector
        int dataSize = vertexData.size();

        glBindBuffer(GL_ARRAY_BUFFER, VBO);
        glBufferData(GL_ARRAY_BUFFER, dataSize * sizeof(float), dataArr, GL_STATIC_DRAW);

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

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

    void draw()
    {
        glBindVertexArray(VAO);
        glDrawArrays(GL_TRIANGLE_FAN, 0, 3 * (size - 2));
        glBindVertexArray(0);
    }

private:
    unsigned int VBO, VAO;
};

int main( int, char** )
{
    glfwSetErrorCallback( []( int, const char* desc ) { std::cerr << desc << "\n"; std::exit( EXIT_FAILURE ); } );
    glfwInit();
    glfwWindowHint( GLFW_CONTEXT_VERSION_MAJOR, 3 );
    glfwWindowHint( GLFW_CONTEXT_VERSION_MINOR, 3 );
    glfwWindowHint( GLFW_OPENGL_FORWARD_COMPAT, GLFW_TRUE );
    glfwWindowHint( GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE );
    GLFWwindow* window = glfwCreateWindow( 600, 600, "GLFW", NULL, NULL );
    glfwMakeContextCurrent( window );
    gladLoadGLLoader( (GLADloadproc)glfwGetProcAddress );

    Circle * circle = new Circle();

    GLuint prog = glCreateProgram();
    AttachShader( prog, GL_VERTEX_SHADER, vert );
    AttachShader( prog, GL_FRAGMENT_SHADER, frag );
    glLinkProgram( prog );
    CheckStatus( prog, false );
    glUseProgram( prog );

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

        int w, h;
        glfwGetFramebufferSize( window, &w, &h );
        glViewport( 0, 0, w, h );

        glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

        circle->draw();

        glfwSwapBuffers( window );
    }

    glfwTerminate();
}