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TextureTransform

TextureTransform is an internal helper class for Transform, responsible for managing resources and state required for reading from and/or writing to Texture objects. It auto creates Texture objects when requested, creates Framebuffer objects. Maintains all texture bindings, when swapping is eanbled, two binding objects are created for easy switching of all WebGL resource binginds.

NOTE: In following sections 'texture transform' is used to refer to 'reading from and/or writing to Texture objects'.

Constructor​

Transform(gl : WebGL2RenderingContext, props: Object)​

  • gl (WebGLRenderingContext) gl - context
  • props (Object, Optional) - contains following data.
    • sourceTextures (Object, Optional) - key and value pairs, where key is the name of vertex shader attribute and value is the corresponding Texture object.
    • targetTexture (Texture|String, Optional) - Texture object to which data to be written. When it is a String, it must be one of the source texture attributes name, a new texture object is cloned from it.
    • targetTextureVarying (String) : varying name used in vertex shader who's data should go into target texture.
    • swapTexture (String) : source texture attribute name, that is swapped with target texture every time swap() is called.
    • fs (String, Optional) - fragment shader string, when rendering to a texture, fragments can be processed using this custom shader, when not specified, pass through fragment shader will be used.

Methods (Model props)​

getDrawOptions(opts: Object) : Object​

Returns options required when performing Model.draw() options.

  • opts (Object) - Any existing opts.attributes , opts.parameters, and opts.uniforms will be merged with new values.

Returns an Object : attributes, framebuffer, uniforms, discard, parameters

updateModelProps(props: Object) : Object​

Updates input props object used to build Model object, with data required for texture transform.

  • props (Object) - props for building Model object, it will updated with required options ({vs, fs, modules, uniforms, inject}) for texture transform.

Returns updated object.

Methods (Resource management)​

swap()​

If swapTexture is provided during construction, performs source and feedback buffers swap as per the swapTexture mapping.

update(props: Object)​

Updates bindings for source and target texture.

  • props (Object) - contains following data.
    • sourceTextures (Object, Optional) - key and value pairs, where key is the name of vertex shader attribute and value is the corresponding Texture object.
    • targetTexture (Texture|String, Optional) - Texture object to which data to be written. When it is a String, it must be one of the source texture attributes name, a new texture object is cloned from it.

Methods (Accessors)​

getTargetTexture() : Texture​

Returns current target texture object.

getData([options : Object]) : ArrayBufferView​

Reads and returns data from current target texture.

  • options.packed (Boolean, Optional, Default: false) - When true, data is packed to the actual size varyings. When false return array contains 4 values (R, G, B and A) for each element. Un-used element value will be 0 for R, G and B and 1 for A channel.

getFramebuffer() : Framebuffer​

Returns current Framebuffer object.