GPU Pro 6

494 VII 3D Engine Design

float3 gv [3] , v [3];

// Compute grid −space positions from world−space positions ;

// g SceneLBFbox contains the left , bottom, and front points

// of world−space bounding box of the grid

gv [0] = ( input [0].f3WorldSpacePos − g_SceneLBFbox . xyz )/

f3CellSize ;

gv [1] = ( input [1].f3WorldSpacePos − g_SceneLBFbox . xyz )/

f3CellSize ;

gv [2] = ( input [2].f3WorldSpacePos − g_SceneLBFbox . xyz )/

f3CellSize ;

// Compute triangle edges

float3 d0 = gv [1] − gv [0];

float3 d1 = gv [2] − gv [0];

// Compute triangle normal

float3 N = normalize( cross ( d0 , d1 ));

float3 C =( 1.0f /3.0f ) ( gv [0] + gv [1] + gv [2] );

// Move eye posi