OpenGL ES 1.1 to 2.0 a major change?

Question

I'm creating an iPhone app with cocos2d and I'm trying to make use of the following OpenGL ES 1.1 code. However, I'm not good with OpenGL and my app makes use of OpenGL ES 2.0 so I need to convert it.

Thus I was wondering, how difficult would it be to convert the following code from ES 1.1 to ES 2.0? Is there some source that could tell me which methods need replacing etc?

-(void) draw
{
    glDisableClientState(GL_COLOR_ARRAY);
    glDisableClientState(GL_TEXTURE_COORD_ARRAY);
    glDisable(GL_TEXTURE_2D);

    glColor4ub(_color.r, _color.g, _color.b, _opacity);
    glLineWidth(1.0f);
    glEnable(GL_LINE_SMOOTH);

    if (_opacity != 255)
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    //non-GL code here

    if (_opacity != 255)
        glBlendFunc(CC_BLEND_SRC, CC_BLEND_DST);

    glEnableClientState(GL_COLOR_ARRAY);
    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
    glEnable(GL_TEXTURE_2D);
}

Answer 1

It will not be that easy if you're not so fit in OpenGL.

OpenGL ES 2.0 doesn't have a fixed-function pipeline anymore. This means you have to manage vertex transformations, lighting, texturing and the like all yourself using GLSL vertex and fragment shaders. You also have to keep track of the transformation matrices yourself, there are no glMatrixMode, glPushMatrix, glTranslate, ... anymore.

There are also no buitlin vertex attributes anymore (like glVertex, glColor, ...). So these functions, along with the corresponding array functions (like glVertexPointer, glColorPointer, ...) and gl(En/Dis)ableClientState, have been reomved, too. Instead you need the generic vertex attribute functions (glVertexAttrib, glVertexAttribPointer and gl(En/Dis)ableVertexAttribArray, which behave similarly) together with a corresponding vertex shader to give these attributes their correct meaning.

I suggest you look into a good OpenGL ES 2.0 tutorial or book, as porting from 1.1 to 2.0 is really a major change, at least if you never have heard anything about shaders.