This chapter is from the book
This chapter is from the book
This chapter is from the book
Explicit Casts
Standard type casts for the built-in scalar data types defined in Table 4.1 will perform appropriate conversion (except void and half 4). In the next example, f stores 0x3F800000 and i stores 0x1, which is the floating-point value 1.0f in f converted to an integer value:
float f = 1.0f; int i = (int)f;
Explicit casts between vector types are not legal. The following examples will generate a compilation error:
int4 i; uint4 u = (uint4)i; // compile error float4 f; int4 i = (int4)f; // compile error float4 f; int8 i = (int8)f; // compile error
Scalar to vector conversions are performed by casting the scalar to the desired vector data type. Type casting will also perform the appropriate arithmetic conversion. Conversions to built-in integer vector types are performed with the round-toward-zero rounding mode. Conversions to built-in floating-point vector types are performed with the round-to-nearest rounding mode. When casting a bool to a vector integer data type, the vector components will be set to -1 (that is, all bits are set) if the bool value is true and 0 otherwise.
Here are some examples of explicit casts:
float4 f = 1.0f;
float4 va = (float4)f; // va is a float4 vector
// with elements ( f, f, f, f )
uchar u = 0xFF;
float4 vb = (float4)u; // vb is a float4 vector with elements
// ( (float)u, (float)u,
// (float)u, (float)u )
float f = 2.0f;
int2 vc = (int2)f; // vc is an int2 vector with elements
// ( (int)f, (int)f )
uchar4 vtrue =(uchar4)true; // vtrue is a uchar4 vector with
// elements(0xFF, 0xFF, 0xFF, 0xFF)