bmap_to_cubemap

bmap_to_cubemap( BMAP*)

Converts a six-sided sky cube bitmap into a cubic environment map, which can be used for enviroment mapping or shader effects.

Parameters:

BMAP* - pointer to sky cube bitmap

Remarks:

The bmap must look like a sky cube (see image below): consisting of 6 adjacent square cube faces in the order south, east, north, west, down, up. Thus its width must be six times larger than its height. The faces must be tiled in a way that they can be wrapped around a cube. Each cube face must be a power of 2 in size.
Some old 3D cards (ATI) do not support cubic environment maps with cube sizes larger than 256x256.
For mipmapped environment maps, create the mipmaps before calling bmap_to_cubemap (like bmap_to_cubemap(bmap_to_mipmap(skymap)). Creating mipmaps afterwards will produce an invalid environment map.
For rendering into a face of an environment map, set the view pos_x parameter to the pixel position of the beginning of the face you want to render into.

Speed:

Slow

Edition:

C P

Example:

BMAP* bmpEnviro = "skybox+6.tga";

MATERIAL* mtlEnviro =
{
   skin2 = bmpEnviro;
   effect = "
      texture mtlSkin2;
      technique enviro
      {
         pass P0
         {
            Texture[0] = <mtlSkin2>;
            AddressU[0] = Clamp; // don't wrap around edges
            AddressV[0] = Clamp;
            ColorOp[0] = SelectArg1; // ignore the ambient light
            ColorArg1[0] = Texture;
            TexCoordIndex[0] = CameraSpaceReflectionVector;
            TextureTransformFlags[0] = Count3;
         }
      }

      technique fallback { pass p0 { } } // empty fallback causes normal rendering without effect
   ";
}

function mtlEnviro_startup()
{
   bmap_to_cubemap(mtlEnviro.skin2);
}

See also:

CUBE, view.bmap

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