Castle Game Engine: CastleGLCubeMaps

# Unit CastleGLCubeMaps
Description | Uses | Classes, Interfaces, Objects and Records | Functions and Procedures | Types | Constants | Variables
## Description OpenGL utilities for cube (environment) maps. ## Uses CastleVectors CastleCubeMaps CastleImages CastleDDS CastleRenderingCamera CastleGLImages Castle3D GL GLU GLExt CastleGLUtils ## Overview ### Functions and Procedures
`procedure SHVectorGLCapture( var SHVector: array of Single; const CapturePoint: TVector3Single; const Render: TCubeMapRenderSimpleFunction; const MapScreenX, MapScreenY: Integer; const ScaleColor: Single);`
`procedure GLCaptureCubeMapImages( const Images: TCubeMapImages; const CapturePoint: TVector3Single; const Render: TRenderFromViewFunction; const ProjectionNear, ProjectionFar: Single);`
`function GLCaptureCubeMapDDS( const Size: Cardinal; const CapturePoint: TVector3Single; const Render: TRenderFromViewFunction; const ProjectionNear, ProjectionFar: Single): TDDSImage;`
`procedure GLCaptureCubeMapTexture( const Tex: TGLuint; const Size: Cardinal; const CapturePoint: TVector3Single; const Render: TRenderFromViewFunction; const ProjectionNear, ProjectionFar: Single; RenderToTexture: TGLRenderToTexture);`
### Types
`TCubeMapRenderSimpleFunction = procedure (ForCubeMap: boolean);`
`TCubeMapImages = array [TCubeMapSide] of TCastleImage;`
## Description ### Functions and Procedures
`procedure SHVectorGLCapture( var SHVector: array of Single; const CapturePoint: TVector3Single; const Render: TCubeMapRenderSimpleFunction; const MapScreenX, MapScreenY: Integer; const ScaleColor: Single);`
Calculate spherical harmonics basis describing environment rendered by OpenGL. Environment is rendered by Render(true) callback, from the CapturePoint. It's rendered to color buffer, and captured as grayscale. Captured pixel value is just assumed to be the value of spherical function at this direction. It's also scaled by ScaleColor (since rendering to OpenGL catches values in 0..1 range, but SH vector can express values from any range). This changes glViewport, so be sure to reset glViewport to something normal after calling this. The maps will be drawn in the color buffer (from positions MapScreenX, Y), so will actually be visible (call this before GLClear or such if you want to hide them).
`procedure GLCaptureCubeMapImages( const Images: TCubeMapImages; const CapturePoint: TVector3Single; const Render: TRenderFromViewFunction; const ProjectionNear, ProjectionFar: Single);`
Capture cube map by rendering environment from CapturePoint. Environment is rendered by Render callback that must honour camera described in RenderingCamera object. RenderingCamera.Target will be set to rtCubeMapEnvironment. RenderingCamera camera will be set to appropriate views from the CapturePoint. You should at least load RenderingCamera.Matrix to OpenGL modelview matrix before rendering your 3D scene. Cube map is recorded in six images you provide in the Images parameter. These must be already created TCastleImage instances, with the exact same size. (They do not have to be square, or have power-of-two size, or honor GL_MAX_CUBE_MAP_TEXTURE_SIZE_ARB limit, as we do not initialize actual OpenGL cube map here. You can use generated images for any purpose.) The classes of these images will also matter — e.g. use TGrayscaleImage to capture scene as grayscale, use TRGBImage for RGB colors. This changes glViewport, so be sure to reset glViewport to something normal after calling this. ProjectionNear, ProjectionFar parameters will be used to set GL projection matrix. ProjectionFar may be equal to ZFarInfinity, as always.
`function GLCaptureCubeMapDDS( const Size: Cardinal; const CapturePoint: TVector3Single; const Render: TRenderFromViewFunction; const ProjectionNear, ProjectionFar: Single): TDDSImage;`
Capture cube map to DDS image by rendering environment from CapturePoint. See GLCaptureCubeMapImages for documentation, this works the same, but it creates TDDSImage instance containing all six images (oriented as appropriate for DDS).
`procedure GLCaptureCubeMapTexture( const Tex: TGLuint; const Size: Cardinal; const CapturePoint: TVector3Single; const Render: TRenderFromViewFunction; const ProjectionNear, ProjectionFar: Single; RenderToTexture: TGLRenderToTexture);`
Capture cube map to OpenGL cube map texture by rendering environment from CapturePoint. See GLCaptureCubeMapImages for documentation, this works the same, but it captures images to given OpenGL texture name Tex. Tex must already be created cube map texture (with OpenGL size and internal formats set), with square images of Size. This also means that Size must be a valid OpenGL cube map texture size, you can check it by GLImages.IsCubeMapTextureSized. This captures the cube map images to "zero" texture level. If you use mipmaps, it's your problem how to generate other texture levels — in the simplest case, call GenerateMipmap(GL_TEXTURE_CUBE_MAP). It uses RenderToTexture to render to the texture, so it will use framebuffer if available, and it's fast.
### Types
`TCubeMapRenderSimpleFunction = procedure (ForCubeMap: boolean);`
`TCubeMapImages = array [TCubeMapSide] of TCastleImage;`
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