概览
以下函数将数值矢量类型转换为另一种类型，或将一种颜色表示法转换为另一种表示法。
摘要
| 函数 | |
|---|---|
| convert | 转换数值矢量 |
| rsPackColorTo8888 | 从 float 创建 uchar4 RGBA |
| rsUnpackColor8888 | 从 uchar4 创建 float4 RGBA |
| rsYuvToRGBA | 将 YUV 值转换为 RGBA |
函数
convert ：转换数值矢量
| char2 convert_char2(char2 v); | |
| char2 convert_char2(double2 v); | 添加于 API level 21 |
| char2 convert_char2(float2 v); | |
| char2 convert_char2(half2 v); | 添加于 API level 24 |
| char2 convert_char2(int2 v); | |
| char2 convert_char2(long2 v); | 添加于 API level 21 |
| char2 convert_char2(short2 v); | |
| char2 convert_char2(uchar2 v); | |
| char2 convert_char2(uint2 v); | |
| char2 convert_char2(ulong2 v); | 添加于 API level 21 |
| char2 convert_char2(ushort2 v); | |
| char3 convert_char3(char3 v); | |
| char3 convert_char3(double3 v); | 添加于 API level 21 |
| char3 convert_char3(float3 v); | |
| char3 convert_char3(half3 v); | 添加于 API level 24 |
| char3 convert_char3(int3 v); | |
| char3 convert_char3(long3 v); | 添加于 API level 21 |
| char3 convert_char3(short3 v); | |
| char3 convert_char3(uchar3 v); | |
| char3 convert_char3(uint3 v); | |
| char3 convert_char3(ulong3 v); | 添加于 API level 21 |
| char3 convert_char3(ushort3 v); | |
| char4 convert_char4(char4 v); | |
| char4 convert_char4(double4 v); | 添加于 API level 21 |
| char4 convert_char4(float4 v); | |
| char4 convert_char4(half4 v); | 添加于 API level 24 |
| char4 convert_char4(int4 v); | |
| char4 convert_char4(long4 v); | 添加于 API level 21 |
| char4 convert_char4(short4 v); | |
| char4 convert_char4(uchar4 v); | |
| char4 convert_char4(uint4 v); | |
| char4 convert_char4(ulong4 v); | 添加于 API level 21 |
| char4 convert_char4(ushort4 v); | |
| double2 convert_double2(char2 v); | 添加于 API level 21 |
| double2 convert_double2(double2 v); | 添加于 API level 21 |
| double2 convert_double2(float2 v); | 添加于 API level 21 |
| double2 convert_double2(half2 v); | 添加于 API level 24 |
| double2 convert_double2(int2 v); | 添加于 API level 21 |
| double2 convert_double2(long2 v); | 添加于 API level 21 |
| double2 convert_double2(short2 v); | 添加于 API level 21 |
| double2 convert_double2(uchar2 v); | 添加于 API level 21 |
| double2 convert_double2(uint2 v); | 添加于 API level 21 |
| double2 convert_double2(ulong2 v); | 添加于 API level 21 |
| double2 convert_double2(ushort2 v); | 添加于 API level 21 |
| double3 convert_double3(char3 v); | 添加于 API level 21 |
| double3 convert_double3(double3 v); | 添加于 API level 21 |
| double3 convert_double3(float3 v); | 添加于 API level 21 |
| double3 convert_double3(half3 v); | 添加于 API level 24 |
| double3 convert_double3(int3 v); | 添加于 API level 21 |
| double3 convert_double3(long3 v); | 添加于 API level 21 |
| double3 convert_double3(short3 v); | 添加于 API level 21 |
| double3 convert_double3(uchar3 v); | 添加于 API level 21 |
| double3 convert_double3(uint3 v); | 添加于 API level 21 |
| double3 convert_double3(ulong3 v); | 添加于 API level 21 |
| double3 convert_double3(ushort3 v); | 添加于 API level 21 |
| double4 convert_double4(char4 v); | 添加于 API level 21 |
| double4 convert_double4(double4 v); | 添加于 API level 21 |
| double4 convert_double4(float4 v); | 添加于 API level 21 |
| double4 convert_double4(half4 v); | 添加于 API level 24 |
| double4 convert_double4(int4 v); | 添加于 API level 21 |
| double4 convert_double4(long4 v); | 添加于 API level 21 |
| double4 convert_double4(short4 v); | 添加于 API level 21 |
| double4 convert_double4(uchar4 v); | 添加于 API level 21 |
| double4 convert_double4(uint4 v); | 添加于 API level 21 |
| double4 convert_double4(ulong4 v); | 添加于 API level 21 |
| double4 convert_double4(ushort4 v); | 添加于 API level 21 |
| float2 convert_float2(char2 v); | |
| float2 convert_float2(double2 v); | 添加于 API level 21 |
| float2 convert_float2(float2 v); | |
| float2 convert_float2(half2 v); | 添加于 API level 24 |
| float2 convert_float2(int2 v); | |
| float2 convert_float2(long2 v); | 添加于 API level 21 |
| float2 convert_float2(short2 v); | |
| float2 convert_float2(uchar2 v); | |
| float2 convert_float2(uint2 v); | |
| float2 convert_float2(ulong2 v); | 添加于 API level 21 |
| float2 convert_float2(ushort2 v); | |
| float3 convert_float3(char3 v); | |
| float3 convert_float3(double3 v); | 添加于 API level 21 |
| float3 convert_float3(float3 v); | |
| float3 convert_float3(half3 v); | 添加于 API level 24 |
| float3 convert_float3(int3 v); | |
| float3 convert_float3(long3 v); | 添加于 API level 21 |
| float3 convert_float3(short3 v); | |
| float3 convert_float3(uchar3 v); | |
| float3 convert_float3(uint3 v); | |
| float3 convert_float3(ulong3 v); | 添加于 API level 21 |
| float3 convert_float3(ushort3 v); | |
| float4 convert_float4(char4 v); | |
| float4 convert_float4(double4 v); | 添加于 API level 21 |
| float4 convert_float4(float4 v); | |
| float4 convert_float4(half4 v); | 添加于 API level 24 |
| float4 convert_float4(int4 v); | |
| float4 convert_float4(long4 v); | 添加于 API level 21 |
| float4 convert_float4(short4 v); | |
| float4 convert_float4(uchar4 v); | |
| float4 convert_float4(uint4 v); | |
| float4 convert_float4(ulong4 v); | 添加于 API level 21 |
| float4 convert_float4(ushort4 v); | |
| half2 convert_half2(char2 v); | 添加于 API level 24 |
| half2 convert_half2(double2 v); | 添加于 API level 24 |
| half2 convert_half2(float2 v); | 添加于 API level 24 |
| half2 convert_half2(half2 v); | 添加于 API level 24 |
| half2 convert_half2(int2 v); | 添加于 API level 24 |
| half2 convert_half2(long2 v); | 添加于 API level 24 |
| half2 convert_half2(short2 v); | 添加于 API level 24 |
| half2 convert_half2(uchar2 v); | 添加于 API level 24 |
| half2 convert_half2(uint2 v); | 添加于 API level 24 |
| half2 convert_half2(ulong2 v); | 添加于 API level 24 |
| half2 convert_half2(ushort2 v); | 添加于 API level 24 |
| half3 convert_half3(char3 v); | 添加于 API level 24 |
| half3 convert_half3(double3 v); | 添加于 API level 24 |
| half3 convert_half3(float3 v); | 添加于 API level 24 |
| half3 convert_half3(half3 v); | 添加于 API level 24 |
| half3 convert_half3(int3 v); | 添加于 API level 24 |
| half3 convert_half3(long3 v); | 添加于 API level 24 |
| half3 convert_half3(short3 v); | 添加于 API level 24 |
| half3 convert_half3(uchar3 v); | 添加于 API level 24 |
| half3 convert_half3(uint3 v); | 添加于 API level 24 |
| half3 convert_half3(ulong3 v); | 添加于 API level 24 |
| half3 convert_half3(ushort3 v); | 添加于 API level 24 |
| half4 convert_half4(char4 v); | 添加于 API level 24 |
| half4 convert_half4(double4 v); | 添加于 API level 24 |
| half4 convert_half4(float4 v); | 添加于 API level 24 |
| half4 convert_half4(half4 v); | 添加于 API level 24 |
| half4 convert_half4(int4 v); | 添加于 API level 24 |
| half4 convert_half4(long4 v); | 添加于 API level 24 |
| half4 convert_half4(short4 v); | 添加于 API level 24 |
| half4 convert_half4(uchar4 v); | 添加于 API level 24 |
| half4 convert_half4(uint4 v); | 添加于 API level 24 |
| half4 convert_half4(ulong4 v); | 添加于 API level 24 |
| half4 convert_half4(ushort4 v); | 添加于 API level 24 |
| int2 convert_int2(char2 v); | |
| int2 convert_int2(double2 v); | 添加于 API level 21 |
| int2 convert_int2(float2 v); | |
| int2 convert_int2(half2 v); | 添加于 API level 24 |
| int2 convert_int2(int2 v); | |
| int2 convert_int2(long2 v); | 添加于 API level 21 |
| int2 convert_int2(short2 v); | |
| int2 convert_int2(uchar2 v); | |
| int2 convert_int2(uint2 v); | |
| int2 convert_int2(ulong2 v); | 添加于 API level 21 |
| int2 convert_int2(ushort2 v); | |
| int3 convert_int3(char3 v); | |
| int3 convert_int3(double3 v); | 添加于 API level 21 |
| int3 convert_int3(float3 v); | |
| int3 convert_int3(half3 v); | 添加于 API level 24 |
| int3 convert_int3(int3 v); | |
| int3 convert_int3(long3 v); | 添加于 API level 21 |
| int3 convert_int3(short3 v); | |
| int3 convert_int3(uchar3 v); | |
| int3 convert_int3(uint3 v); | |
| int3 convert_int3(ulong3 v); | 添加于 API level 21 |
| int3 convert_int3(ushort3 v); | |
| int4 convert_int4(char4 v); | |
| int4 convert_int4(double4 v); | 添加于 API level 21 |
| int4 convert_int4(float4 v); | |
| int4 convert_int4(half4 v); | 添加于 API level 24 |
| int4 convert_int4(int4 v); | |
| int4 convert_int4(long4 v); | 添加于 API level 21 |
| int4 convert_int4(short4 v); | |
| int4 convert_int4(uchar4 v); | |
| int4 convert_int4(uint4 v); | |
| int4 convert_int4(ulong4 v); | 添加于 API level 21 |
| int4 convert_int4(ushort4 v); | |
| long2 convert_long2(char2 v); | 添加于 API level 21 |
| long2 convert_long2(double2 v); | 添加于 API level 21 |
| long2 convert_long2(float2 v); | 添加于 API level 21 |
| long2 convert_long2(half2 v); | 添加于 API level 24 |
| long2 convert_long2(int2 v); | 添加于 API level 21 |
| long2 convert_long2(long2 v); | 添加于 API level 21 |
| long2 convert_long2(short2 v); | 添加于 API level 21 |
| long2 convert_long2(uchar2 v); | 添加于 API level 21 |
| long2 convert_long2(uint2 v); | 添加于 API level 21 |
| long2 convert_long2(ulong2 v); | 添加于 API level 21 |
| long2 convert_long2(ushort2 v); | 添加于 API level 21 |
| long3 convert_long3(char3 v); | 添加于 API level 21 |
| long3 convert_long3(double3 v); | 添加于 API level 21 |
| long3 convert_long3(float3 v); | 添加于 API level 21 |
| long3 convert_long3(half3 v); | 添加于 API level 24 |
| long3 convert_long3(int3 v); | 添加于 API level 21 |
| long3 convert_long3(long3 v); | 添加于 API level 21 |
| long3 convert_long3(short3 v); | 添加于 API level 21 |
| long3 convert_long3(uchar3 v); | 添加于 API level 21 |
| long3 convert_long3(uint3 v); | 添加于 API level 21 |
| long3 convert_long3(ulong3 v); | 添加于 API level 21 |
| long3 convert_long3(ushort3 v); | 添加于 API level 21 |
| long4 convert_long4(char4 v); | 添加于 API level 21 |
| long4 convert_long4(double4 v); | 添加于 API level 21 |
| long4 convert_long4(float4 v); | 添加于 API level 21 |
| long4 convert_long4(half4 v); | 添加于 API level 24 |
| long4 convert_long4(int4 v); | 添加于 API level 21 |
| long4 convert_long4(long4 v); | 添加于 API level 21 |
| long4 convert_long4(short4 v); | 添加于 API level 21 |
| long4 convert_long4(uchar4 v); | 添加于 API level 21 |
| long4 convert_long4(uint4 v); | 添加于 API level 21 |
| long4 convert_long4(ulong4 v); | 添加于 API level 21 |
| long4 convert_long4(ushort4 v); | 添加于 API level 21 |
| short2 convert_short2(char2 v); | |
| short2 convert_short2(double2 v); | 添加于 API level 21 |
| short2 convert_short2(float2 v); | |
| short2 convert_short2(half2 v); | 添加于 API level 24 |
| short2 convert_short2(int2 v); | |
| short2 convert_short2(long2 v); | 添加于 API level 21 |
| short2 convert_short2(short2 v); | |
| short2 convert_short2(uchar2 v); | |
| short2 convert_short2(uint2 v); | |
| short2 convert_short2(ulong2 v); | 添加于 API level 21 |
| short2 convert_short2(ushort2 v); | |
| short3 convert_short3(char3 v); | |
| short3 convert_short3(double3 v); | 添加于 API level 21 |
| short3 convert_short3(float3 v); | |
| short3 convert_short3(half3 v); | 添加于 API level 24 |
| short3 convert_short3(int3 v); | |
| short3 convert_short3(long3 v); | 添加于 API level 21 |
| short3 convert_short3(short3 v); | |
| short3 convert_short3(uchar3 v); | |
| short3 convert_short3(uint3 v); | |
| short3 convert_short3(ulong3 v); | 添加于 API level 21 |
| short3 convert_short3(ushort3 v); | |
| short4 convert_short4(char4 v); | |
| short4 convert_short4(double4 v); | 添加于 API level 21 |
| short4 convert_short4(float4 v); | |
| short4 convert_short4(half4 v); | 添加于 API level 24 |
| short4 convert_short4(int4 v); | |
| short4 convert_short4(long4 v); | 添加于 API level 21 |
| short4 convert_short4(short4 v); | |
| short4 convert_short4(uchar4 v); | |
| short4 convert_short4(uint4 v); | |
| short4 convert_short4(ulong4 v); | 添加于 API level 21 |
| short4 convert_short4(ushort4 v); | |
| uchar2 convert_uchar2(char2 v); | |
| uchar2 convert_uchar2(double2 v); | 添加于 API level 21 |
| uchar2 convert_uchar2(float2 v); | |
| uchar2 convert_uchar2(half2 v); | 添加于 API level 24 |
| uchar2 convert_uchar2(int2 v); | |
| uchar2 convert_uchar2(long2 v); | 添加于 API level 21 |
| uchar2 convert_uchar2(short2 v); | |
| uchar2 convert_uchar2(uchar2 v); | |
| uchar2 convert_uchar2(uint2 v); | |
| uchar2 convert_uchar2(ulong2 v); | 添加于 API level 21 |
| uchar2 convert_uchar2(ushort2 v); | |
| uchar3 convert_uchar3(char3 v); | |
| uchar3 convert_uchar3(double3 v); | 添加于 API level 21 |
| uchar3 convert_uchar3(float3 v); | |
| uchar3 convert_uchar3(half3 v); | 添加于 API level 24 |
| uchar3 convert_uchar3(int3 v); | |
| uchar3 convert_uchar3(long3 v); | 添加于 API level 21 |
| uchar3 convert_uchar3(short3 v); | |
| uchar3 convert_uchar3(uchar3 v); | |
| uchar3 convert_uchar3(uint3 v); | |
| uchar3 convert_uchar3(ulong3 v); | 添加于 API level 21 |
| uchar3 convert_uchar3(ushort3 v); | |
| uchar4 convert_uchar4(char4 v); | |
| uchar4 convert_uchar4(double4 v); | 添加于 API level 21 |
| uchar4 convert_uchar4(float4 v); | |
| uchar4 convert_uchar4(half4 v); | 添加于 API level 24 |
| uchar4 convert_uchar4(int4 v); | |
| uchar4 convert_uchar4(long4 v); | 添加于 API level 21 |
| uchar4 convert_uchar4(short4 v); | |
| uchar4 convert_uchar4(uchar4 v); | |
| uchar4 convert_uchar4(uint4 v); | |
| uchar4 convert_uchar4(ulong4 v); | 添加于 API level 21 |
| uchar4 convert_uchar4(ushort4 v); | |
| uint2 convert_uint2(char2 v); | |
| uint2 convert_uint2(double2 v); | 添加于 API level 21 |
| uint2 convert_uint2(float2 v); | |
| uint2 convert_uint2(half2 v); | 添加于 API level 24 |
| uint2 convert_uint2(int2 v); | |
| uint2 convert_uint2(long2 v); | 添加于 API level 21 |
| uint2 convert_uint2(short2 v); | |
| uint2 convert_uint2(uchar2 v); | |
| uint2 convert_uint2(uint2 v); | |
| uint2 convert_uint2(ulong2 v); | 添加于 API level 21 |
| uint2 convert_uint2(ushort2 v); | |
| uint3 convert_uint3(char3 v); | |
| uint3 convert_uint3(double3 v); | 添加于 API level 21 |
| uint3 convert_uint3(float3 v); | |
| uint3 convert_uint3(half3 v); | 添加于 API level 24 |
| uint3 convert_uint3(int3 v); | |
| uint3 convert_uint3(long3 v); | 添加于 API level 21 |
| uint3 convert_uint3(short3 v); | |
| uint3 convert_uint3(uchar3 v); | |
| uint3 convert_uint3(uint3 v); | |
| uint3 convert_uint3(ulong3 v); | 添加于 API level 21 |
| uint3 convert_uint3(ushort3 v); | |
| uint4 convert_uint4(char4 v); | |
| uint4 convert_uint4(double4 v); | 添加于 API level 21 |
| uint4 convert_uint4(float4 v); | |
| uint4 convert_uint4(half4 v); | 添加于 API level 24 |
| uint4 convert_uint4(int4 v); | |
| uint4 convert_uint4(long4 v); | 添加于 API level 21 |
| uint4 convert_uint4(short4 v); | |
| uint4 convert_uint4(uchar4 v); | |
| uint4 convert_uint4(uint4 v); | |
| uint4 convert_uint4(ulong4 v); | 添加于 API level 21 |
| uint4 convert_uint4(ushort4 v); | |
| ulong2 convert_ulong2(char2 v); | 添加于 API level 21 |
| ulong2 convert_ulong2(double2 v); | 添加于 API level 21 |
| ulong2 convert_ulong2(float2 v); | 添加于 API level 21 |
| ulong2 convert_ulong2(half2 v); | 添加于 API level 24 |
| ulong2 convert_ulong2(int2 v); | 添加于 API level 21 |
| ulong2 convert_ulong2(long2 v); | 添加于 API level 21 |
| ulong2 convert_ulong2(short2 v); | 添加于 API level 21 |
| ulong2 convert_ulong2(uchar2 v); | 添加于 API level 21 |
| ulong2 convert_ulong2(uint2 v); | 添加于 API level 21 |
| ulong2 convert_ulong2(ulong2 v); | 添加于 API level 21 |
| ulong2 convert_ulong2(ushort2 v); | 添加于 API level 21 |
| ulong3 convert_ulong3(char3 v); | 添加于 API level 21 |
| ulong3 convert_ulong3(double3 v); | 添加于 API level 21 |
| ulong3 convert_ulong3(float3 v); | 添加于 API level 21 |
| ulong3 convert_ulong3(half3 v); | 添加于 API level 24 |
| ulong3 convert_ulong3(int3 v); | 添加于 API level 21 |
| ulong3 convert_ulong3(long3 v); | 添加于 API level 21 |
| ulong3 convert_ulong3(short3 v); | 添加于 API level 21 |
| ulong3 convert_ulong3(uchar3 v); | 添加于 API level 21 |
| ulong3 convert_ulong3(uint3 v); | 添加于 API level 21 |
| ulong3 convert_ulong3(ulong3 v); | 添加于 API level 21 |
| ulong3 convert_ulong3(ushort3 v); | 添加于 API level 21 |
| ulong4 convert_ulong4(char4 v); | 添加于 API level 21 |
| ulong4 convert_ulong4(double4 v); | 添加于 API level 21 |
| ulong4 convert_ulong4(float4 v); | 添加于 API level 21 |
| ulong4 convert_ulong4(half4 v); | 添加于 API level 24 |
| ulong4 convert_ulong4(int4 v); | 添加于 API level 21 |
| ulong4 convert_ulong4(long4 v); | 添加于 API level 21 |
| ulong4 convert_ulong4(short4 v); | 添加于 API level 21 |
| ulong4 convert_ulong4(uchar4 v); | 添加于 API level 21 |
| ulong4 convert_ulong4(uint4 v); | 添加于 API level 21 |
| ulong4 convert_ulong4(ulong4 v); | 添加于 API level 21 |
| ulong4 convert_ulong4(ushort4 v); | 添加于 API level 21 |
| ushort2 convert_ushort2(char2 v); | |
| ushort2 convert_ushort2(double2 v); | 添加于 API level 21 |
| ushort2 convert_ushort2(float2 v); | |
| ushort2 convert_ushort2(half2 v); | 添加于 API level 24 |
| ushort2 convert_ushort2(int2 v); | |
| ushort2 convert_ushort2(long2 v); | 添加于 API level 21 |
| ushort2 convert_ushort2(short2 v); | |
| ushort2 convert_ushort2(uchar2 v); | |
| ushort2 convert_ushort2(uint2 v); | |
| ushort2 convert_ushort2(ulong2 v); | 添加于 API level 21 |
| ushort2 convert_ushort2(ushort2 v); | |
| ushort3 convert_ushort3(char3 v); | |
| ushort3 convert_ushort3(double3 v); | 添加于 API level 21 |
| ushort3 convert_ushort3(float3 v); | |
| ushort3 convert_ushort3(half3 v); | 添加于 API level 24 |
| ushort3 convert_ushort3(int3 v); | |
| ushort3 convert_ushort3(long3 v); | 添加于 API level 21 |
| ushort3 convert_ushort3(short3 v); | |
| ushort3 convert_ushort3(uchar3 v); | |
| ushort3 convert_ushort3(uint3 v); | |
| ushort3 convert_ushort3(ulong3 v); | 添加于 API level 21 |
| ushort3 convert_ushort3(ushort3 v); | |
| ushort4 convert_ushort4(char4 v); | |
| ushort4 convert_ushort4(double4 v); | 添加于 API level 21 |
| ushort4 convert_ushort4(float4 v); | |
| ushort4 convert_ushort4(half4 v); | 添加于 API level 24 |
| ushort4 convert_ushort4(int4 v); | |
| ushort4 convert_ushort4(long4 v); | 添加于 API level 21 |
| ushort4 convert_ushort4(short4 v); | |
| ushort4 convert_ushort4(uchar4 v); | |
| ushort4 convert_ushort4(uint4 v); | |
| ushort4 convert_ushort4(ulong4 v); | 添加于 API level 21 |
| ushort4 convert_ushort4(ushort4 v); |
将矢量从一种数值类型转换为另一种类型。转换是逐项完成的。
例如，调用 a = convert_short3(b); 等同于执行 a.x = (short)b.x; a.y = (short)b.y; a.z = (short)b.z;。
将浮点值转换为整数类型会截断。
将过大的数字转换为目标类型会导致未定义结果。例如，将包含 1.0e18 的 float 转换为 short 是未定义的。使用 clamp() 可避免此问题。
rsPackColorTo8888 ：从 float 创建 uchar4 RGBA
| uchar4 rsPackColorTo8888(float r, float g, float b); | |
| uchar4 rsPackColorTo8888(float r, float g, float b, float a); | |
| uchar4 rsPackColorTo8888(float3 color); | |
| uchar4 rsPackColorTo8888(float4 color); |
参数
| r | 红色分量。 |
|---|---|
| g | 绿色分量。 |
| b | 蓝色分量。 |
| a | Alpha 分量。 |
| color | 包含 R、G、B 和 A 值的 3 或 4 个浮点数的向量。 |
将三个或四个浮点 RGBA 值打包成一个 uchar4。
输入值通常在 0.0f 到 1.0f（含）之间。对于超出此范围的输入值，结果输出将被钳位到 0 到 255 之间。由于此钳位操作可能是在输入值乘以 255.f 并转换为整数之后进行的，因此大于 INT_MAX/255.f 或小于 INT_MIN/255.f 的输入值会导致未定义的行为。
如果未指定 Alpha 分量，则默认为 1.0，即结果的 Alpha 将设置为 255。
rsUnpackColor8888 ：从 uchar4 创建一个 float4 RGBA
将 uchar4 颜色解包为 float4。结果浮点数将在 0.0 到 1.0（含）之间。