Castle Game Engine: CastleScene: Class TSceneRenderingAttributes

# Class TSceneRenderingAttributes
Description | Hierarchy | Fields | Methods | Properties
## Unit CastleScene ## Declaration `type TSceneRenderingAttributes = class(TRenderingAttributes)` ## Description no description available, TRenderingAttributes description follows Various properties that control rendering done with TGLRenderer. They are collected here, in a class separate from TGLRenderer, because various things (like TCastleScene and TCastlePrecalculatedAnimation) wrap TGLRenderer instances and hide it, but still they want to allow user to change these attributes. ## Hierarchy TPersistent TRenderingAttributes TSceneRenderingAttributes ## Overview ### Fields
| `internal const DefaultBlendingSourceFactor = GL_SRC_ALPHA;`
| `internal const DefaultBlendingDestinationFactor = GL_ONE_MINUS_SRC_ALPHA;`
| `internal const DefaultBlendingSort = false;`
| `internal const DefaultWireframeColor: TVector3Single = (0, 0, 0);`
| `var OnCreate: TRenderingAttributesEvent; static;`
### Methods
| `constructor Create; override;`
| `destructor Destroy; override;`
| `procedure Assign(Source: TPersistent); override;`
### Properties
| `property Blending: boolean read FBlending write SetBlending default true;`
| `property BlendingSourceFactor: TGLenum read FBlendingSourceFactor write SetBlendingSourceFactor default DefaultBlendingSourceFactor;`
| `property BlendingDestinationFactor: TGLenum read FBlendingDestinationFactor write SetBlendingDestinationFactor default DefaultBlendingDestinationFactor;`
| `property BlendingSort: boolean read FBlendingSort write SetBlendingSort default DefaultBlendingSort;`
| `property ControlBlending: boolean read FControlBlending write SetControlBlending default true;`
| `property WireframeEffect: TWireframeEffect read FWireframeEffect write FWireframeEffect default weNormal;`
| `property WireframeColor: TVector3Single read FWireframeColor write FWireframeColor;`
| `property UseOcclusionQuery: boolean read FUseOcclusionQuery write SetUseOcclusionQuery default false;`
| `property UseHierarchicalOcclusionQuery: boolean read FUseHierarchicalOcclusionQuery write FUseHierarchicalOcclusionQuery default false;`
| `property DebugHierOcclusionQueryResults: boolean read FDebugHierOcclusionQueryResults write FDebugHierOcclusionQueryResults default false;`
## Description ### Fields
| `internal const DefaultBlendingSourceFactor = GL_SRC_ALPHA;`
| `internal const DefaultBlendingDestinationFactor = GL_ONE_MINUS_SRC_ALPHA;`
Default value of Attributes.BlendingDestinationFactor. See TSceneRenderingAttributes.BlendingDestinationFactor. Using ONE_MINUS_SRC_ALPHA is the standard value for 3D graphic stuff, often producing best results. However, it causes troubles when multiple transparent shapes are visible on the same screen pixel. For closed convex 3D objects, using backface culling (solid = TRUE for geometry) helps. For multiple transparent shapes, sorting the transparent shapes helps, see TSceneRenderingAttributes.BlendingSort. Sometimes, no solution works for all camera angles. Another disadvantage of ONE_MINUS_SRC_ALPHA may be that the color of opaque shapes disappears too quickly from resulting image (since GL_ONE_MINUS_SRC_ALPHA scales it down). So the image may be darker than you like. You can instead consider using GL_ONE, that doesn't require sorting and never has problems with multiple transparent shapes. On the other hand, it only adds to the color, often making too bright results.
| `internal const DefaultBlendingSort = false;`
| `internal const DefaultWireframeColor: TVector3Single = (0, 0, 0);`
| `var OnCreate: TRenderingAttributesEvent; static;`
Adjust attributes of all loaded resources.
### Methods
| `constructor Create; override;`
| `destructor Destroy; override;`
| `procedure Assign(Source: TPersistent); override;`
### Properties
| `property Blending: boolean read FBlending write SetBlending default true;`
Render partially transparent objects. More precisely: if this is `True`, all shapes with transparent materials or textures with non-trivial (not only yes/no) alpha channel will be rendered using OpenGL blending (with depth test off, like they should for OpenGL). If this attribute is `False`, everything will be rendered as opaque.
| `property BlendingSourceFactor: TGLenum read FBlendingSourceFactor write SetBlendingSourceFactor default DefaultBlendingSourceFactor;`
Blending function parameters, used when Blending. See OpenGL documentation of glBlendFunc for possible values here. See also DefaultBlendingDestinationFactor for comments about GL_ONE and GL_ONE_MINUS_SRC_ALPHA. Note that this is only a default, VRML/X3D model can override this for specific shapes by using our extension BlendMode node. See [http://castle-engine.sourceforge.net/x3d_extensions.php#section_ext_blending].
| `property BlendingDestinationFactor: TGLenum read FBlendingDestinationFactor write SetBlendingDestinationFactor default DefaultBlendingDestinationFactor;`
| `property BlendingSort: boolean read FBlendingSort write SetBlendingSort default DefaultBlendingSort;`
| `property ControlBlending: boolean read FControlBlending write SetControlBlending default true;`
Setting this to `False` disables any modification of OpenGL blending (and depth mask) state by TCastleScene. This makes every other Blending setting ignored, and is useful only if you set your own OpenGL blending parameters when rendering this scene.
| `property WireframeEffect: TWireframeEffect read FWireframeEffect write FWireframeEffect default weNormal;`
You can use this to turn on some effects related to rendering model in special modes. When this is weNormal (default), nothing special is done, which means that model polygons are simply passed to OpenGL. Whether this results in filled or wireframe, depends on OpenGL glPolygonMode setting, filled by default. How the wireframe effects work when Mode = rmDepth is undefined now. Just don't use Mode = rmDepth if you're unsure. See description of TWireframeEffect for what other modes do.
| `property WireframeColor: TVector3Single read FWireframeColor write FWireframeColor;`
Wireframe color, used with some WireframeEffect values. Default value is DefaultWireframeColor.
| `property UseOcclusionQuery: boolean read FUseOcclusionQuery write SetUseOcclusionQuery default false;`
Should we use ARB_occlusion_query (if available) to avoid rendering shapes that didn't pass occlusion test in previous frame. Ignored if GPU doesn't support ARB_occlusion_query. `True` may give you a large speedup in some scenes. OTOH, a lag of one frame may happen between an object should be rendered and it actually appears. When you render more than once the same instance of TCastleScene scene, you should not activate it (as the occlusion query doesn't make sense if each following render of the scene takes place at totally different translation). Also, when rendering something more than just one TCastleScene scene (maybe many times the same TCastleScene instance, maybe many different TCastleScene instances, maybe some other 3D objects) you should try to sort rendering order from the most to the least possible occluder (otherwise occlusion query will not be as efficient at culling). This is ignored if UseHierarchicalOcclusionQuery.
| `property UseHierarchicalOcclusionQuery: boolean read FUseHierarchicalOcclusionQuery write FUseHierarchicalOcclusionQuery default false;`
Should we use ARB_occlusion_query (if available) with a hierarchical algorithm to avoid rendering shapes that didn't pass occlusion test in previous frame. Ignored if GPU doesn't support ARB_occlusion_query. `True` may give you a large speedup in some scenes. This method doesn't impose any lag of one frame (like UseOcclusionQuery). This requires the usage of TCastleSceneCore.OctreeRendering. Also, it always does frustum culling (like fcBox for now), regardless of TCastleScene.OctreeFrustumCulling setting. The algorithm used underneath is "Coherent Hierarchical Culling", described in detail in "GPU Gems 2", Chapter 6: "Hardware Occlusion Queries Made Useful", by Michael Wimmer and Jiri Bittner. Online on [http://http.developer.nvidia.com/GPUGems2/gpugems2_chapter06.html].
| `property DebugHierOcclusionQueryResults: boolean read FDebugHierOcclusionQueryResults write FDebugHierOcclusionQueryResults default false;`
View only the shapes that were detected as visible by occlusion query in last Render. Use this only after render with UseHierarchicalOcclusionQuery. TODO: for UseOcclusionQuery I would also like to make it work, for now not done as frustum information is gone. This will disable actual occlusion query, instead reusing results from last occlusion query done when this debug flag was `False`. Useful to quickly visualize the benefits of occlusion query.
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