Re: How to set up a 3D texture with following settings

henryjoye@xxxxxxxxx wrote:

Dimensions: dim[0], dim[1], dim[2]
Texture values: we need to store values in channel R and
channel A,

Use GL_LUMINANCE_ALPHA as format (there is no RED_ALPHA texture
format), with GL_MODULATE texture mode and
glColor3f(1.0,0.0,0.0);

the value range for each channel is (0,
dim[0]*dim[1]*dim[2]) (it is the multiplication of size of data
in three directions).

Texel values are either 8, 12 or 16 bits (integer) per channel,
or 32 bits per channel for a float texture.

512 = 2^9
512^3 = (2^9)^3 = 2^9*3 = 2^27, so you need a 32 bits per channel
texture, which leaves you with float textures.

But there's also another problem: 512^3 * 8 bytes = 1GiB. Only
professional grade cards have that much memory. Unless you got
one of the latest and biggest Quadro cards I doubt that this
will work. And even if so the fill rate will abyssmal, the whole
memory must be sparsely accessed, a chache trash nightmare. If
you are upon high resolution volume date rendering better choose
one of the implicit tesselation approaches, or get some
dedicated volume raycaster hardware (used in medical and
geodesic applications).

Usually 3D textures are 64x64x64 max, oftenly a lot smaller.

Wolfgang Draxinger
--
E-Mail address works, Jabber: hexarith@xxxxxxxxxx, ICQ: 134682867

.

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