OpenGL 忽略四边形并使它们成为三角形-C/C++问题

OpenGL ignores Quads and makes them Triangles(OpenGL 忽略四边形并使它们成为三角形)

本文介绍了OpenGL 忽略四边形并使它们成为三角形的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

这是我第二次制作游戏引擎，但我现在有点卡住了，因为我无法弄清楚为什么会发生这种情况，无论我发送什么对象，OpenGL 都只会在其上绘制一个白色三角形屏幕中央，像这样.

This is the second time I'm making a game engine, but I'm a little stuck right now, since I cannot figure out why this is happening, no matter what object I send, OpenGL only draws a White Triangle on the center of the screen, like this.

我什至从渲染器和相机对象上的上一个引擎中复制了我的旧代码，其行为仍然相同，所以我猜它与渲染脚本有关.

I've even coppied my old code from my last engine on the Renderer and the Camera Objects, still acts the same, so I´m guessing it has something to do with the Render Script.

渲染器:

Renderer2D::Renderer2D(const Shader& shader) {
    this->shader = shader;
    this->Init();
}

Renderer2D::~Renderer2D() {
    glDeleteVertexArrays(1, &this->QuadVAO);
}

void Renderer2D::Render(Texture & texture, iVec2 position, iVec2 size, float rotation, iVec3 color) {
    this->shader.Use();
    iMat4 model;

    using namespace glm;
    model = translate(model, iVec3(position.x, position.y, 0.0f));
    /*
    model = translate(model, iVec3(size.x * 0.5f, size.y * 0.5f, 0.0f));
    model = rotate(model, rotation, iVec3(0.0f, 0.0f, 1.0f));
    model = translate(model, iVec3(size.x * -0.5f, size.y * -0.5f, 0.0f));
    */
    model = glm::scale(model, iVec3(size.x, size.y, 1.0f));

    this->shader.SetMatrix4("model2D", model);
    this->shader.SetVector3f("color2D", color);

    glActiveTexture(GL_TEXTURE0);
    texture.Bind();

    glBindVertexArray(this->QuadVAO);
    glDrawArrays(GL_TRIANGLES, 0, 6);
    glBindVertexArray(0);
}

void Renderer2D::Init() {
    U16 VBO;

    float vertices[] = {
        // Pos      // Tex
        0.0f, 1.0f, 0.0f, 1.0f,
        1.0f, 0.0f, 1.0f, 0.0f,
        0.0f, 0.0f, 0.0f, 0.0f,

        0.0f, 1.0f, 0.0f, 1.0f,
        1.0f, 1.0f, 1.0f, 1.0f,
        1.0f, 0.0f, 1.0f, 0.0f
    };

    glGenVertexArrays(1, &this->QuadVAO);
    glGenBuffers(1, &VBO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    glBindVertexArray(this->QuadVAO);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void*)0);

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


顶点着色器:
#version 330 core
layout (location = 0) in vec4 vertex; // <vec2 position, vec2 texCoords>

out vec2 TexCoords;

uniform mat4 view2D;
uniform mat4 model2D;
uniform mat4 projection2D;

void main()
{
    TexCoords = vertex.zw;
    gl_Position = projection2D * view2D * mode2Dl * vec4(vertex.xy, 0.0, 1.0);
}

<小时>

顶点着色器:
#version 330 core
layout (location = 0) in vec4 vertex; // <vec2 position, vec2 texCoords>

out vec2 TexCoords;

uniform mat4 view2D;
uniform mat4 model2D;
uniform mat4 projection2D;

void main()
{
    TexCoords = vertex.zw;
    gl_Position = projection2D * view2D * model2D * vec4(vertex.xy, 0.0, 1.0);
}

片段着色器:
#version 330 core
in vec2 TexCoords;
out vec4 color2D; //Fixed the error!

uniform sampler2D image2D;
uniform vec3 color2D;

void main()
{    
    color2D = vec4(color2D, 1.0) * texture(image2D, TexCoords);
}  

资源.cpp
Shader Resources::LoadShaderFromFile(const char * vertexSource, const char * fragmentSource) {
    using namespace std;
    string vertexCode;
    string fragmentCode;

    try {
        ifstream vertexShaderFile(vertexSource);
        ifstream fragmentShaderFile(fragmentSource);
        stringstream vShaderStream, fShaderStream;

        vShaderStream << vertexShaderFile.rdbuf();
        fShaderStream << fragmentShaderFile.rdbuf();

        vertexShaderFile.close();
        fragmentShaderFile.close();

        vertexCode = vShaderStream.str();
        fragmentCode = fShaderStream.str();
    }
    catch (exception e) {
        cout << "ERROR::SHADER: Failed to read shader files" << std::endl;
    }

    const char *vShaderCode = vertexCode.c_str();
    const char *fShaderCode = fragmentCode.c_str();

    Shader shader;
    shader.Compile(vShaderCode, fShaderCode);

    return shader;
}


推荐答案
您的着色器甚至无法编译.当您声明矩阵统一时，您使用名称 model2D、view2D 和 projection2D:
You'r shader doesn't even compile. When you declare the matrix uniforms, then you use the names model2D, view2D and projection2D:
uniform mat4 view2D;
uniform mat4 model2D;
uniform mat4 projection2D;

但是当您使用矩阵时，您会使用名称 view、model 和 projection:
But when you use the matrices, then you use the names view, model and projection:
gl_Position = projection * view * model * vec4(vertex.xy, 0.0, 1.0);

<小时>
我建议检查着色器对象是否编译成功以及程序对象链接是否成功.




I recommend to check if the shader objects compiled successfully and if the program object link successfully.

着色器编译是否成功可以通过<代码>glGetShaderiv 和参数GL_COMPILE_STATUS.

If the compiling of a shader succeeded can be checked by glGetShaderiv and the parameter GL_COMPILE_STATUS.

例如

GLuint shaderObj = .... ;
glCompileShader( shaderObj );

GLint status = GL_TRUE;
glGetShaderiv( shaderObj, GL_COMPILE_STATUS, &status );
if ( status == GL_FALSE )
{
    GLint logLen;
    glGetShaderiv( shaderObj, GL_INFO_LOG_LENGTH, &logLen );
    std::vector< char >log( logLen );
    GLsizei written;
    glGetShaderInfoLog( shaderObj, logLen, &written, log.data() );
    std::cout << "compile error:" << std::endl << log.data() << std::endl;
}

可以通过检查程序链接是否成功glGetProgramiv 和参数 GL_LINK_STATUS.

例如

GLuint progObj = ....;
glLinkProgram( progObj );

GLint status = GL_TRUE;
glGetProgramiv( progObj, GL_LINK_STATUS, &status );
if ( status == GL_FALSE )
{
    GLint logLen;
    glGetProgramiv( progObj, GL_INFO_LOG_LENGTH, &logLen );
    std::vector< char >log( logLen );
    GLsizei written;
    glGetProgramInfoLog( progObj, logLen, &written, log.data() );
    std::cout  << "link error:" << std::endl << log.data() << std::endl;
}

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