OpenGL ignores Quads and makes them Triangles

问题

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.

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.

Renderer:

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);
}

Vertex Shader:

#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);
}

---

Edit:

Vertex Shader:

#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);
}

Fragment Shader:

#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);
}  

Resources.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;
}

回答1:

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;

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);

---

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

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

e.g.

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;
}

If the linking of a program was successful can be checked by glGetProgramiv and the parameter GL_LINK_STATUS.

e.g.

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;
}

来源：https://stackoverflow.com/questions/53218925/opengl-ignores-quads-and-makes-them-triangles