Handle textures with texture arrays in modern OpenGL.

[rtoumazet]

• 1 texture array for vdp2 parts (8*8)
• 1 texture array for vdp1 parts (max 504x255, ie 512x256 in POT)
• 1 texture array for bitmaps Detect the array size for vdp1 parts

[rtoumazet]

Number of array level is limited by GL_MAX_ARRAY_TEXTURE_LAYERS. Number is at least 2048 in OpengL 4.6, and at least 256 in OpenGL 3.0

[rtoumazet]

Textures are generated in a 256 layers texture array (minimum for OpenGL 3.3), each layer being a texture atlas of 512x256 pixels. In theory, the maximum number of different VDP2 cells that could be stored by the Saturn at a given time is 0x80000 (ie both RBG at maximum size, with every cell different). Maximum VDP1 texture size is 504x255.

[rtoumazet]

Implemented as 512*512 texture array