List of alternatives for features not found in OpenGLES

Question

There are many features that exist in OpenGL, but not in OpenGLES 1.1 (for iPhone).

Is there a list or resource that lists some alternative functions that can be used in OpenGLES 1.1?

For example:

• gluOrtho2D
• glPolygonMode
• glVertex3f
• etc.

Answer 1

"The OpenGL ES 1.1.12 difference specification" ( http://www.khronos.org/registry/gles/specs/1.1/es_cm_spec_1.1.12.pdf ) lists the differences between OpenGL ES 1.X and OpenGL 1.5,

iPhone uses OpenGL ES 1.1

I also recommend that you make a list of the OpenGL functions that you invoke and check the ES documentation to make sure that they are fully / partially supported.

Answer 2

on the man page for gluOrtho2D

 DESCRIPTION gluOrtho2D sets up a two-dimensional orthographic viewing region. This is equivalent to calling glOrtho with near=-1 and far=1. 

Instead of using glVertex3f you should use Vertex arrays, see link

Answer 3

For simplicity, the OpenGLES standard has used numerous convenience features as well as inefficient cushioned features for convenience.

Where it is mostly easier to use the most commonly used functions or to provide optimized implementations of common commands.

The two examples you provided gluOrtho2D are just a wrapper for glOrtho, and glPolygonMode can be achieved with glTriangle with a bit of preprocessing.

I'm not sure about the perse list, but if the function does not exist, most likely the man page will tell you what similar functions it performs as a wrapper or alternatives that you can use.

Answer 4

You can replace glOrtho for gluOrtho2D. The only thing you need to do is set your near and far clipping.

GlPolygonMode doesn't seem to be part of the OpenGLES specification, because only filled triangles are supported. See here .