/**
|
* Decodes a unit-length vector in 'oct' encoding to a normalized 3-component Cartesian vector.
|
* The 'oct' encoding is described in "A Survey of Efficient Representations of Independent Unit Vectors",
|
* Cigolle et al 2014: http://jcgt.org/published/0003/02/01/
|
*
|
* @name czm_octDecode
|
* @param {vec2} encoded The oct-encoded, unit-length vector
|
* @param {float} range The maximum value of the SNORM range. The encoded vector is stored in log2(rangeMax+1) bits.
|
* @returns {vec3} The decoded and normalized vector
|
*/
|
vec3 czm_octDecode(vec2 encoded, float range)
|
{
|
if (encoded.x == 0.0 && encoded.y == 0.0) {
|
return vec3(0.0, 0.0, 0.0);
|
}
|
|
encoded = encoded / range * 2.0 - 1.0;
|
vec3 v = vec3(encoded.x, encoded.y, 1.0 - abs(encoded.x) - abs(encoded.y));
|
if (v.z < 0.0)
|
{
|
v.xy = (1.0 - abs(v.yx)) * czm_signNotZero(v.xy);
|
}
|
|
return normalize(v);
|
}
|
|
/**
|
* Decodes a unit-length vector in 'oct' encoding to a normalized 3-component Cartesian vector.
|
* The 'oct' encoding is described in "A Survey of Efficient Representations of Independent Unit Vectors",
|
* Cigolle et al 2014: http://jcgt.org/published/0003/02/01/
|
*
|
* @name czm_octDecode
|
* @param {vec2} encoded The oct-encoded, unit-length vector
|
* @returns {vec3} The decoded and normalized vector
|
*/
|
vec3 czm_octDecode(vec2 encoded)
|
{
|
return czm_octDecode(encoded, 255.0);
|
}
|
|
/**
|
* Decodes a unit-length vector in 'oct' encoding packed into a floating-point number to a normalized 3-component Cartesian vector.
|
* The 'oct' encoding is described in "A Survey of Efficient Representations of Independent Unit Vectors",
|
* Cigolle et al 2014: http://jcgt.org/published/0003/02/01/
|
*
|
* @name czm_octDecode
|
* @param {float} encoded The oct-encoded, unit-length vector
|
* @returns {vec3} The decoded and normalized vector
|
*/
|
vec3 czm_octDecode(float encoded)
|
{
|
float temp = encoded / 256.0;
|
float x = floor(temp);
|
float y = (temp - x) * 256.0;
|
return czm_octDecode(vec2(x, y));
|
}
|
|
/**
|
* Decodes three unit-length vectors in 'oct' encoding packed into two floating-point numbers to normalized 3-component Cartesian vectors.
|
* The 'oct' encoding is described in "A Survey of Efficient Representations of Independent Unit Vectors",
|
* Cigolle et al 2014: http://jcgt.org/published/0003/02/01/
|
*
|
* @name czm_octDecode
|
* @param {vec2} encoded The packed oct-encoded, unit-length vectors.
|
* @param {vec3} vector1 One decoded and normalized vector.
|
* @param {vec3} vector2 One decoded and normalized vector.
|
* @param {vec3} vector3 One decoded and normalized vector.
|
*/
|
void czm_octDecode(vec2 encoded, out vec3 vector1, out vec3 vector2, out vec3 vector3)
|
{
|
float temp = encoded.x / 65536.0;
|
float x = floor(temp);
|
float encodedFloat1 = (temp - x) * 65536.0;
|
|
temp = encoded.y / 65536.0;
|
float y = floor(temp);
|
float encodedFloat2 = (temp - y) * 65536.0;
|
|
vector1 = czm_octDecode(encodedFloat1);
|
vector2 = czm_octDecode(encodedFloat2);
|
vector3 = czm_octDecode(vec2(x, y));
|
}
|
