CCTextureAtlas _indices overflow

[PatriceJiang]

ref: #18755

_indices can exceed 2^16-1 which leads to overflow.

fix:
change type to GLuint

[PatriceJiang]

when i*4+3 > 2^16 - 1 _indices go wrong.

cocos2d-x/cocos/renderer/CCTextureAtlas.cpp

Lines 240 to 251 in bb32eee

	for( int i=0; i < _capacity; i++)
	{
	_indices[i*6+0] = i*4+0;
	_indices[i*6+1] = i*4+1;
	_indices[i*6+2] = i*4+2;
	// inverted index. issue #179
	_indices[i*6+3] = i*4+3;
	_indices[i*6+4] = i*4+2;
	_indices[i*6+5] = i*4+1;
	}
	}

_capacity was limited to 16383

[stevetranby]

I may be wrong ... but I don't believe this PR is acceptable unless it were refactored to only apply conditionally based on capability support by extension?

I think to use UINT as index type would require availability and support of the extension 'GL_OES_element_index_uint' and I don't believe this is required with OpenGL ES 2 (WebGL 1)??

I believe OpenGL ES 3 (and thus WebGL 2) requires supporting this extension.

https://www.khronos.org/registry/OpenGL/specs/es/2.0/es_cm_spec_2.0.pdf

"Indexing support with ubyte and ushort indices is supported. Support for uint indices is not required
by OpenGL ES 2.0. If an implementation supports uint indices, it will export the OES element index -
uint extension."

Let me know if I'm mistaken.

[stevetranby]

The full spec doesn't even mention the extension.
https://www.khronos.org/registry/OpenGL/specs/es/2.0/es_full_spec_2.0.pdf

type must be one of UNSIGNED_BYTE or UNSIGNED_SHORT, indicating that
the values in indices are indices of GL type ubyte or ushort, respectively. mode
specifies what kind of primitives are constructed;

[PatriceJiang]

@stevetranby you are correct. I would try to fix this issue in another way.