iOS Development-OpenGL es screenshot

Previously wrote a regular screen: http://blog.csdn.net/hitwhylz/article/details/17189351

But finding this way is useless for OpenGL. The data obtained is empty.

So here are the next OpenGL ES screens.

1. Initialize.

Caeagllayer *eagllayer = (Caeagllayer *) Self.layer;  Eagllayer.drawableproperties = @{      keagldrawablepropertyretainedbacking: [NSNumber Numberwithbool:yes],      Keagldrawablepropertycolorformat:keaglcolorformatrgba8  

2. Declare the method.

-(uiimage*) Snapshot: (uiview*) eaglview{glint backingwidth, backingheight;  Bind the color renderbuffer used to render the OpenGL ES View//If Your application only creates a single color Renderbuffer which is already bound at the this point,//The This is the redundant, but it's needed if you ' re dealing w        ith multiple renderbuffers.        Note, replace "Viewrenderbuffer" with the actual name of the Renderbuffer object defined in your class.        Glbindrenderbufferoes (Gl_renderbuffer_oes, Viewrenderbuffer); Get the size of the backing Caeagllayer glgetrenderbufferparameterivoes (Gl_renderbuffer_oes, Gl_renderbuffer_wid    Th_oes, &backingwidth);        Glgetrenderbufferparameterivoes (Gl_renderbuffer_oes, Gl_renderbuffer_height_oes, &backingHeight);        Nsinteger x = 0, y = 0, Width = backingwidth, height = backingheight;        Nsinteger datalength = width * Height * 4; Glubyte *data = (glubyte*) malloc (datalength * sizeof (glubyte));       Read pixel data from the framebuffer glpixelstorei (gl_pack_alignment, 4);            Glreadpixels (x, y, width, height, Gl_rgba, gl_unsigned_byte, data); Create a cgimage with the pixel data//If your OpenGL ES content are opaque, use Kcgimagealphanoneskiplast to IG Nore the alpha channel//Otherwise, use kcgimagealphapremultipliedlast cgdataproviderref ref = Cgdataprovid        Ercreatewithdata (null, data, datalength, NULL);        Cgcolorspaceref colorspace = Cgcolorspacecreatedevicergb (); Cgimageref iref = cgimagecreate (width, height, 8, +, Width * 4, colorspace, Kcgbitmapbyteorder32big | kcgimagealphapremul Tipliedlast, ref, NULL, True, Kcgrenderingintentdef            Ault); OpenGL ES measures data in PIXELS//Create A graphics context with the target size measured in POINTS NS        Integer widthinpoints, heightinpoints; if (NULL! = UigraphicsbeginImagecontextwithoptions) {//on IOS 4 and later, use Uigraphicsbeginimagecontextwithoptions to take the SC                Ale into consideration//Set the scale parameter to your OpenGL ES view ' s Contentscalefactor So, you get a high-resolution snapshot when it value is greater than 1.0 cgfloat scale = Eaglview                . Contentscalefactor;                Widthinpoints = Width/scale;                Heightinpoints = Height/scale;            Uigraphicsbeginimagecontextwithoptions (Cgsizemake (widthinpoints, heightinpoints), NO, scale); } else {//on IOS prior to 4, fall-Uigraphicsbeginimagecontext Widthinpo                INTs = width;                heightinpoints = height;            Uigraphicsbeginimagecontext (Cgsizemake (widthinpoints, heightinpoints));            } cgcontextref Cgcontext = Uigraphicsgetcurrentcontext (); UIKit coordinate system is upside down toGl/quartz coordinate system//Flip the cgimage by rendering it to the flipped bitmap context//the size of        The destination area was measured in POINTS cgcontextsetblendmode (Cgcontext, kcgblendmodecopy);                Cgcontextdrawimage (Cgcontext, CGRectMake (0.0, 0.0, widthinpoints, heightinpoints), iref);                Retrieve the UIImage from the current context UIImage *image = Uigraphicsgetimagefromcurrentimagecontext ();        Uigraphicsendimagecontext ();        Clean up free (data);        Cfrelease (ref);        Cfrelease (ColorSpace);        Cgimagerelease (IREF); return image;

3. Use

Call the above method.

-(uiimage*) Snapshot: (uiview*) Eaglview