Question

I get this strange distorted primitive shape (instead of a square) when i move the primitive through the x and y co-ordinates.

Here is a snapshot:
http://img535.imageshack.us/img535/9046/screenshot20120126at122.png

I’m using orthogonal projection since i want to render in 2D.

Here is the render code:

//vertex definition
static GLfloat qdt[] = {
    30.0f, 60.0f, -0.03f,
    30.0f, 30.0f, -0.03f,
    60.0f, 60.0f, -0.03f,
    60.0f, 30.0f, -0.03f
};

//clear buffers
glClear(GL_COLOR_BUFFER_BIT);// also tried using GL_DEPTH_BUFFER_BIT

//load matrices
glLoadIdentity();

//drawing
glVertexPointer(3, GL_FLOAT, 0, &qdt[0]);
glColor4f(1.0f, 0.0f, 0.0f, 1.0f);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 12);

//swap buffers
[glContext presentRenderbuffer:GL_RENDERBUFFER_OES];

I’ve disabled the depth buffers too.
It would be nice if someone points out the mistakes which is causing this distortion.
Thanks in advance.

Answer 1

Replace 12 by 4, because you draw 4 vertices:

glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);