vertex attribute (declaration) vertex stream (memory pool)
这两部分 通过attribute
里面对memory的描述把两部分 vbo 和attribute bind together
slot attribute offset streamIndex stride stream
0 RGBA32F pos 0 0 16 0 memoryaddress
1 RGBA32F normal 16(slot0 RGBA32F 4X4) 0
2 RG32F uv 32 0
example2:
slot attribute offset streamIndex stride divisor(??not quite sure) stream
0 RGBA32F pos 0 0 16(slot0) 0 memoryaddress0
1 RGBA32F normal 16( slot0 RGBA32F 4X4) 1 24(slot1+slot2) 1 memoryaddress1
2 RG32F uv 32 1
16F是2个字节 X4（RGBA四个通道）
stride offset单位都是byte
SetVertexDeclaration()设置的offset