Sure. So my situation is I have electric potentials defined for particular sets of electrode configurations. Depending on what simulation I’m doing, the textures that need to be fetched are different. Hopefully your situation maps onto this one. I do something like:

/* this constant gets set in the host code, for the particular configuration needed, with:

int all3dfunc = ALL3DFUNC_TRANSFEROPTICS;

cudaMemcpyToSymbol(“d_all3dFuncType”,&all3dfunc,sizeof(int),0,cudaMemcpyHostToDevice);

*/

**constant** int d_all3dFuncType;

// typedef for the function we will be calling

typedef float(*all3dGetPotentials_t)(float x,float y,float z,float* volts,int& status);

// and here is the function pointer

**device** all3dGetPotentials_t Get3dPotentials;

// now the different configurations I have are defined in a set of functions. for example:

**device** inline float

PotentialsTransferOptics(float x,float y,float z,float* volts,int& status)

{

```
float4 paPotentials;
float total = 0;
paPotentials = tex3D(tex3d0,x,y,z);
total+= paPotentials.x * volts[0];
total+= paPotentials.y * volts[1];
total+= paPotentials.z * volts[2];
total+= paPotentials.w * volts[3];
paPotentials = tex3D(tex3d1,x,y,z);
total+= paPotentials.x * volts[4];
total+= paPotentials.y * volts[5];
total+= paPotentials.z * volts[6];
total+= paPotentials.w * volts[7];
// check for electrode hit
if(paPotentials.x > 1.0f)
status = HITELECTRODE;
return total;
```

}

// this enum would be somewhere visible to host and this file

enum all3dFunction_t

{

```
ALL3DFUNC_DUALCELLNORESEJ,
ALL3DFUNC_DUALCELLTK,
ALL3DFUNC_GATEASSEMBLY,
ALL3DFUNC_TRANSFEROPTICS,
ALL3DFUNC_OPTICSANDTRAP,
ALL3DFUNC_NUMBEROFFUNCTIONS
```

};

// array of all possible functions, each with unique set of textures they have to call

**device** all3dGetPotentials_t all3dInterpolate_table[ALL3DFUNC_NUMBEROFFUNCTIONS] = {Potential3dDualCellNoResej,

Potential3dDualCellTurnerKruger,Potential3dGateAssembly,PotentialsTransferOptics,Potential3dTransferOpticsAndTrap};

// finally, there is some device function that needs to use the function pointer

**device** float3

ComputeAccel_All3d(float* volts, float4 pos_pix,int& status,float invmass_amu,float charge)

{

```
// set the function pointer for getting the potentials
Get3dPotentials = all3dInterpolate_table[d_all3dFuncType];
// convert to grid units, position units of texture file
// positions are assumed to be valid
float3 pos_gu;
pos_gu.x = abs(pos_pix.x*d_elecParams[XDIM].guPerPixx);
pos_gu.y = abs(pos_pix.y*d_elecParams[YDIM].guPerPixy);
pos_gu.z = abs(pos_pix.z*d_elecParams[ZDIM].guPerPixz);
float xm = pos_gu.x - 0.5f;
float xp = pos_gu.x + 0.5f;
float ym = pos_gu.y - 0.5f;
float yp = pos_gu.y + 0.5f;
float zm = pos_gu.z - 0.5f;
float zp = pos_gu.z + 0.5f;
// use function pointer
float V2 = (*Get3dPotentials)(xp,pos_gu.y,pos_gu.z,volts,status);
```

etc…