R2Normals.h File Reference

Functions for transforming normal vectors. More...

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Functions
vec2	R2_normalsCompress (const vec3 n)
vec3	R2_normalsDecompress (const vec2 n)
vec3	R2_normalsBitangent (const vec3 n, const vec4 t)
vec3	R2_normalsUnpack (const sampler2D map, const vec2 uv)
vec3	R2_normalsTransform (const vec3 m, const vec3 t, const vec3 b, const vec3 n)
vec3	R2_normalsBumpLocal (const sampler2D t_normal, const vec3 n, const vec3 t, const vec3 b, const vec2 uv)
vec3	R2_normalsBump (const sampler2D t_normal, const mat3x3 m_normal, const vec3 n, const vec3 t, const vec3 b, const vec2 uv)

Detailed Description

Functions for transforming normal vectors.

Definition in file R2Normals.h.

Function Documentation

R2_normalsBitangent()

vec3 R2_normalsBitangent	(	const vec3	n,
		const vec4	t
	)

Compute a bitangent vector given a normal n and tangent vector t, assuming a sign [-1.0, 1.0] stored in t.w.

Parameters

n	A normal vector
t	A tangent vector

Returns

A bitangent vector

Definition at line 58 of file R2Normals.h.

{
  vec3 p = cross (n, t.xyz);
  return p * t.w;
}

R2_normalsBump()

vec3 R2_normalsBump	(	const sampler2D	t_normal,
		const mat3x3	m_normal,
		const vec3	n,
		const vec3	t,
		const vec3	b,
		const vec2	uv
	)

Given a texture consisting of normal vectors t_normal, an object-to-eye-space matrix m_normal, object-space normal n, object-space tangent t, object-space bitangent b, and texture coordinates uv, unpack and transform a vector from the texture, and transform it to eye-space.

Parameters

t_normal	A normal map texture
m_normal	A object-to-eye-space matrix
n	A normal vector
t	A tangent vector
b	A bitangent vector
uv	A set of UV coordinates

Definition at line 144 of file R2Normals.h.

{
  vec3 nl = R2_normalsBumpLocal (t_normal, n, t, b, uv);
  return normalize (m_normal * nl);
}

R2_normalsBumpLocal()

vec3 R2_normalsBumpLocal	(	const sampler2D	t_normal,
		const vec3	n,
		const vec3	t,
		const vec3	b,
		const vec2	uv
	)

Given a texture consisting of normal vectors t_normal, object-space normal n, object-space tangent t, object-space bitangent b, and texture coordinates uv, unpack and transform a vector from the texture, resulting in an object-space peturbed normal.

Parameters

t_normal	A normal map texture
n	A normal vector
t	A tangent vector
b	A bitangent vector
uv	A set of UV coordinates

Definition at line 115 of file R2Normals.h.

{
  vec3 m  = R2_normalsUnpack (t_normal, uv);
  vec3 nn = normalize (n);
  vec3 nt = normalize (t);
  vec3 nb = normalize (b);
  return R2_normalsTransform (m, nt, nb, nn);
}

R2_normalsCompress()

vec2 R2_normalsCompress

(

const vec3

n

)

Compress the (normalized) vector n into two elements using a spheremap transform (Lambert Azimuthal Equal-Area).

Parameters

n	A normal vector

Returns

A compressed normal vector

Definition at line 17 of file R2Normals.h.

{
  float p = sqrt ((n.z * 8.0) + 8.0);
  float x = (n.x / p) + 0.5;
  float y = (n.y / p) + 0.5;
  return vec2 (x, y);
}

R2_normalsDecompress()

vec3 R2_normalsDecompress

(

const vec2

n

)

Decompress the given vector, assuming it was encoded with a spheremap transform (Lambert Azimuthal Equal-Area).

Parameters

n	The compressed normal vector

Returns

A decompressed normal vector

Definition at line 34 of file R2Normals.h.

{
  vec2 fn = vec2 (
    (n.x * 4.0) - 2.0,
    (n.y * 4.0) - 2.0
  );
  float f = dot (fn, fn);
  float g = sqrt (1.0 - (f / 4.0));
  float x = fn.x * g;
  float y = fn.y * g;
  float z = 1.0 - (f / 2.0);
  return vec3 (x, y, z);
}

R2_normalsTransform()

vec3 R2_normalsTransform	(	const vec3	m,
		const vec3	t,
		const vec3	b,
		const vec3	n
	)

Transform the tangent-space vector m into the coordinate system given by the orthonormal vectors {t, b, n}.

Parameters

m	A tangent-space vector
t	A tangent vector
b	A bitangent vector
n	A normal vector

Definition at line 92 of file R2Normals.h.

{
  mat3x3 mat = mat3x3 (t, b, n);
  return normalize (mat * m);
}

R2_normalsUnpack()

vec3 R2_normalsUnpack	(	const sampler2D	map,
		const vec2	uv
	)

Unpack a tangent-space normal vector from the texture map.

Parameters

map	A normal map texture
uv	The UV coordinates

Definition at line 74 of file R2Normals.h.

{
  vec3 rgb = texture (map, uv).xyz;
  return (rgb * 2.0) + (-1.0);
}