OpenGL中的错误绘图模型

Question

So i'm trying to a basic opengl program that reads in an .obj file and then renders it (the obj file contains triangle vertices in the format v 1.000000 2.000000, 3.00000.

So here's my code to do that (im using GLFW and a Golang binding library for it) (also im currently ignoring normals).

gl.Begin(gl.TRIANGLES)
for scanner.Scan() {
    var v0, v1, v2 float32
    t := strings.Split(scanner.Text(), " ")
    line := scanner.Text()
    fmt.Sscanf(line, "v %f %f %f", &v0, &v1, &v2)
    if t[0] == "v" {
        gl.Vertex3f(v0, v1, v2)
    }
}
gl.End()

However when I go to run this the result isnt quite right

I tried it on a few other files I found around the internet and I get similar results. It almost seems like the triangles vertices are offset or something.

Answer 1

You should read all vertices data into array. Obj file contains information about triangles, and how vertices should be indexed. Lines starting with f contains 3 numbers which describes triangles. So your code should look like this (I don't know go):

var vertices [1000*3] float32
for scanner.Scan() {
    var i=0
    var v0, v1, v2 float32
    var vv byte
    t := strings.Split(scanner.Text(), " ")
    line := scanner.Text()
    fmt.Sscanf(line, "%c %f %f %f", &vv, &v0, &v1, &v2)
    if vv == "v" {
        vertices[i] = v0
        vertices[i+1] = v1
        vertices[i+2] = v2
    }
    i = i+3
}
gl.Begin(gl.TRIANGLES)
for scanner.Scan() {
    var v0, v1, v2 int
    var vv byte
    t := strings.Split(scanner.Text(), " ")
    line := scanner.Text()
    fmt.Sscanf(line, "%c %d %d %d", &vv, &v0, &v1, &v2)
    if vv == "f" {
        gl.Vertex3f(vertices[v0], vertices[v1], vertices[v2])
    }
}
gl.End()