GL_TRIANGLES works but GL_QUADS displays nothing

问题

So I'm swapping from one program to another, and I can't figure out why but GL_QUADS will no longer display with the same code. To try and figure out why old code was not working, I made this new, simple code and it STILL does not work.

The setup:

vector <vec3f> squarepoints;
vec3f temper(-0.5f, 0.5f, 0.5f);
squarepoints.push_back(temper);
temper.x += 1.0f;
squarepoints.push_back(temper);
temper.y -= 1.0f;
squarepoints.push_back(temper);
temper.x -= 1.0f;
squarepoints.push_back(temper);
vector <unsigned int> squareindex;
squareindex.push_back(0);
squareindex.push_back(1);
squareindex.push_back(2);
//squareindex.push_back(0);
//squareindex.push_back(2);
squareindex.push_back(3);
GLuint VAOO;
GLuint IBOO;
GLuint VBOO;


glGenVertexArrays(1, &VAOO);
glBindVertexArray(VAOO);

glGenBuffers(1, &VBOO);
glBindBuffer(GL_ARRAY_BUFFER, VBOO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vec3f) * squarepoints.size(), &squarepoints[0], GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT,GL_FALSE, 0, 0);       


glGenBuffers(1, &IBOO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, IBOO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned int) * squareindex.size(), &squareindex[0], GL_STATIC_DRAW);
glBindVertexArray(0);

The drawing:

glBindVertexArray(VAOO);
    glDrawElements(GL_QUADS, squareindex.size(), GL_UNSIGNED_INT, 0);
    glBindVertexArray(0);

This displays nothing. Now if I add in the two commented lines in the setup to make it 6 points and change it to GL_TRIANGLES in the drawing, it all displays perfectly. I am not sure where the fault is lying here, but I've been trying to fix my model loading and other features so long that I'm sure I'm just overlooking something super obvious at this point.

回答1:

GL_QUADS have been removed from core OpenGL 3.1 and above.

来源：https://stackoverflow.com/questions/61387287/why-the-graphic-shown-when-the-primitive-is-triangle-but-it-disappeared-when-the

标签

opengl

vbo

vao