# G2S_SetBlendAlpha

## C Specification

      #include <nitro/gx/g2.h>

      void G2S_SetBlendAlpha(
          int plane1 /* GXBlendPlaneMask */,
          int plane2 /* GXBlendPlaneMask */,
          int ev1,
          int ev2
      );

## Arguments

plane1 | Selects the first target plane for blending (result of logical OR with `GXBlendPlaneMask` type values)
plane2 | Selects the second target plane for blending (result of logical OR with `GXBlendPlaneMask` type values)
`ev1` | alpha-blending coefficient for the first target screen (0 ≤ `ev1` ≤ 31)
`ev2` | alpha-blending coefficient for the second target screen (0 ≤ `ev2` ≤ 31)

## Return Values

None.

## Description

Alpha blending will be performed using the sub 2D Engine if the second target plane immediately follows the first target plane. Even if no OBJ is specified in the first target screen, alpha-blending is performed on the translucent OBJ, bitmap OBJ, and 3D screen.

`GX_BLEND_PLANEMASK_NONE` | No plane is specified.
`GX_BLEND_PLANEMASK_BG0` | Indicates that BG0 is visible.
`GX_BLEND_PLANEMASK_BG1` | Indicates that BG1 is visible.
`GX_BLEND_PLANEMASK_BG2` | Indicates that BG2 is visible.
`GX_BLEND_PLANEMASK_BG3` | Indicates that BG3 is visible.
`GX_BLEND_PLANEMASK_OBJ` | Indicates that OBJs are visible.
`GX_BLEND_PLANEMASK_BD` | Specifies the backdrop plane.

The following indicates the type definition for `GXBlendPlaneMask` types.

    typedef enum
    {
        GX_BLEND_PLANEMASK_NONE = 0x0000,
        GX_BLEND_PLANEMASK_BG0 = 0x0001,
        GX_BLEND_PLANEMASK_BG1 = 0x0002,
        GX_BLEND_PLANEMASK_BG2 = 0x0004,
        GX_BLEND_PLANEMASK_BG3 = 0x0008,
        GX_BLEND_PLANEMASK_OBJ = 0x0010,
        GX_BLEND_PLANEMASK_BD = 0x0020
    }
    GXBlendPlaneMask;

## See Also

`G2S_BlendNone, G2S_SetBlendBrightness, G2S_SetBlendBrightnessExt, G2S_ChangeBlendAlpha, G2S_ChangeBlendBrightness`

## Revision History

02/09/2004 Initial version

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