Native bindings to the APPLE_texture_packed_float extension.

This extension adds two new 3-component floating-point texture formats that fit within a single 32-bit word called R11F_G11F_B10F and RGB9_E5

The first RGB format, R11F_G11F_B10F, stores 5 bits of biased exponent per component in the same manner as 16-bit floating-point formats, but rather than 10 mantissa bits, the red, green, and blue components have 6, 6, and 5 bits respectively. Each mantissa is assumed to have an implied leading one except in the denorm exponent case. There is no sign bit so only non-negative values can be represented. Positive infinity, positivedenorms, and positive NaN values are representable. The value of the fourth component returned by a texture fetch is always 1.0.

The second RGB format, RGB9_E5, stores a single 5-bit exponent (biased up by 15) and three 9-bit mantissas for each respective component. There is no sign bit so all three components must be non-negative. The fractional mantissas are stored without an implied 1 to the left of the decimal point. Neither infinity nor not-a-number (NaN) are representable in this shared exponent format.

Requires GLES 2.0.