R2LogDepth.h File Reference

Logarithmic depth functions. More...

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Functions
float	R2_logDepthPrepareEyeZ (const float z)
float	R2_logDepthEncodePartial (const float z, const float depth_coefficient)
float	R2_logDepthEncodeFull (const float z, const float depth_coefficient)
float	R2_logDepthDecode (const float z, const float depth_coefficient)

Detailed Description

Logarithmic depth functions.

Definition in file R2LogDepth.h.

Function Documentation

R2_logDepthDecode()

float R2_logDepthDecode	(	const float	z,
		const float	depth_coefficient
	)

Decode a depth value that was encoded with the given depth coefficient. Note that in most cases, this will yield a positive eye-space Z value, and must be negated to yield a conventional negative eye-space Z value.

Parameters

z	The depth value
depth_coefficient	The coefficient used during encoding

Returns

The original (positive) eye-space Z value

Definition at line 72 of file R2LogDepth.h.

{
  float half_co  = depth_coefficient * 0.5;
  float exponent = z / half_co;
  return pow (2.0, exponent) - 1.0;
}

R2_logDepthEncodeFull()

float R2_logDepthEncodeFull	(	const float	z,
		const float	depth_coefficient
	)

Fully encode the given eye-space Z value.

Parameters

z	An eye-space Z value
depth_coefficient	The depth coefficient used to encode z

Returns

The fully encoded depth

Definition at line 51 of file R2LogDepth.h.

{
  float half_co = depth_coefficient * 0.5;
  float clamp_z = max (0.000001, z + 1.0);
  return log2 (clamp_z) * half_co;
}

R2_logDepthEncodePartial()

float R2_logDepthEncodePartial	(	const float	z,
		const float	depth_coefficient
	)

Partially encode the given positive eye-space Z value. This partial encoding can be used when performing part of the encoding in a vertex shader and the rest in a fragment shader (for efficiency reasons) - See R2_logDepthPrepareEyeZ.

Parameters

z	An eye-space Z value
depth_coefficient	The depth coefficient used to encode z

Returns

The encoded depth

Definition at line 33 of file R2LogDepth.h.

{
  float half_co = depth_coefficient * 0.5;
  float clamp_z = max (0.000001, z);
  return log2 (clamp_z) * half_co;
}

R2_logDepthPrepareEyeZ()

float R2_logDepthPrepareEyeZ

(

const float

z

)

Prepare an eye-space Z value for encoding. See R2_logDepthEncodePartial.

Parameters

z	An eye-space Z value

Returns

The prepared value

Definition at line 15 of file R2LogDepth.h.

{
  return 1.0 + (-z);
}