GPU Pro 4

74 II Rendering

float2 ComputeUV(

uint faceID , // From SV_PrimitiveID

float2 faceUV , // Position within the face

uint nLog2 , // Log2 of the resolution we want

int texWidth , // Atlas texture width

int resOffset , // Prefix sum for this resolution

int rowOffset , // Start of resolution block in atlas

int borderSize ) // Texel thickness of border on each face

{

// Here we assume a square aspect ratio .

// A non- square aspect would simply scale the height

// relative to width accordingly.

float faceWidth = 1 << nLog2;

float faceHeight = faceWidth;

float borderedFaceWidth = faceWidth + 2* borderSize;

float borderedFaceHeight = borderedFaceWidth;

int nFacesEachRow ...