Trying to draw a simple line loop - opengl-es-2.0

Question

I'm going crazy. All I want to do is draw a simple line loop. But all I get is a diagonal line from the origin out to (-0.5, 0.0, -0.5). What am I doing wrong?
#interface Frustum : NSObject {
GLuint _vertexArray;
GLuint _vertexBuffer;
GLfloat left_side[4][3];
}
- (id) init;
- (GLuint) getVertexArray;
- (void) render;
#end
#implementation Frustum
- (id) init {
left_side[0][0] = -0.5f; left_side[0][1] = 0.0f; left_side[0][2] = -0.5f;
left_side[1][0] = 0.5f; left_side[1][1] = 0.0f; left_side[1][2] = -0.5f;
left_side[2][0] = 0.5f; left_side[2][1] = 0.0f; left_side[2][2] = -0.5f;
left_side[3][0] = -0.5f; left_side[3][1] = 0.0f; left_side[3][2] = -0.5f;
glGenVertexArraysOES(1, &_vertexArray);
glBindVertexArrayOES(_vertexArray);
glGenBuffers(1, &_vertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, _vertexBuffer);
// SOMETHING IS WRONG IN HERE, BUT I DON'T KNOW WHAT!!!!!
glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat)*12, left_side, GL_STATIC_DRAW);
glEnableVertexAttribArray(GLKVertexAttribPosition);
glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, sizeof(left_side), NULL);
glBindVertexArrayOES(0);
}
return self;
}
- (void) render {
glLineWidth(2.0f);
glDrawArrays(GL_LINE_LOOP, 0, 4);
}

Answer 1

Try changing your y or z values, so you form an actual loop.
(-.5, 0, 0 )
(.5, 0, 0 )
(.5, .5, 0)
(-.5 .5, 0 )
will form a line loop. You just have the same y, so that's a line.
Remember, the default camera will looking down the -z axis, so it won't see changes in z (unless you've rotated the camera).