OpenGL Shape Demo

The OpenGL Shape Demo is intended to act as a sandbox for learning how the 10 OpenGL shape modes work. Refer to the following picture and text below for a more detailed discussion:

Rendering Options

points: shows a point at each vertex in Draw Area. Useful for incomplete shapes and for moving vertices.
lines: draws a line through vertices in Draw Area in the order they were placed there
Enable Culling: turns on face removal in default mode - removes "backward" facing triangles regardless of primitive type.
See also Front Face.
Polygon Mode: select between point, line and filled polygon drawing styles.
Note: GL_FILLED is the default.
Front Face: Select between two different ways of determining whether a triangle is facing forward or backward. the orientation of a triangle is determined by the relative ordering of its three points, ie. ClockWise (GL_CW) or CounterClockWise (GL_CCW).
Note: GL_CCW is the default

Dump Coordinates

You can dump the coordinates of what you draw in the Draw Area.
The coordinates are in normalized form. This means that that x and y values are scaled to lie in the range [0,1]. You will wish to scale the points to the size of your intended drawing target. To do this you should apply the following equations to the coordinates:

        x_scaled = target_x_min + (x_norm * target_width)
        y_scaled = target_y_min + (y_norm * target_height)