ErosionShader

Image erosion shader

Specialization of ShaderProgram performing erosion operation on a grayscale image. Erosion is a morphological operations removing pixels on the boundaries of objects in an image. The value of the output pixel is minimum value of all pixels in the neighbourhood which radius is a modifiable parameter.

Extends

• ShaderProgram

Constructors

new ErosionShader()

new ErosionShader(gl, size, radius): ErosionShader

Constructor

Parameters

• gl: WebGL2RenderingContext

WebGL context where program is instantiated

• size: Size

Size of processed (input & output) image

• radius: number = 1

Erosion operation radius

Returns

ErosionShader

Overrides

ShaderProgram.constructor

Properties

fragShader

protected fragShader: null | WebGLShader

Fragment shader

Inherited from

ShaderProgram.fragShader

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frameBuffer

protected frameBuffer: null | WebGLFramebuffer

Frame buffer (output)

Inherited from

ShaderProgram.frameBuffer

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gl

protected gl: WebGL2RenderingContext

WebGL context where program is instantiated

Inherited from

ShaderProgram.gl

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inputs

protected inputs: string[]

Shader texture inputs (names of sampler uniforms)

Inherited from

ShaderProgram.inputs

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outputTexture?

protected optional outputTexture: ImageTexture

Output image texture

Inherited from

ShaderProgram.outputTexture

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shaderProgram

protected shaderProgram: null | WebGLProgram

Shader program

Inherited from

ShaderProgram.shaderProgram

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size

protected size: Size

Size of processed (input & output) image

Inherited from

ShaderProgram.size

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uniforms

protected uniforms: object

Shader uniforms as name-type map object

Index Signature

[key: string]: UniformType

Inherited from

ShaderProgram.uniforms

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uniformsLoc

protected uniformsLoc: object

Unifrom locations

Index Signature

[key: string]: WebGLUniformLocation | null

Inherited from

ShaderProgram.uniformsLoc

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vertAttrs

protected vertAttrs: null | WebGLVertexArrayObject

Vertex attributes

Inherited from

ShaderProgram.vertAttrs

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vertBuffer

protected vertBuffer: null | WebGLBuffer

Vertex buffer

Inherited from

ShaderProgram.vertBuffer

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vertShader

protected vertShader: null | WebGLShader

Vertex shader

Inherited from

ShaderProgram.vertShader

Methods

compile()

protected compile(fragSrc, vertSrc): void

Compile shader program

Allocates and sets up all resources required for shader program, compiles and links shaders.

Parameters

• fragSrc: string

Fragment shader source (copy shader by default)

• vertSrc: string

Vertex shader source (copy shader by default)

Returns

void

Inherited from

ShaderProgram.compile

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dispose()

dispose(): void

Dispose program object

Releases resources and instances allocated by program. Program object cannot be used after calling dispose().

Returns

void

Inherited from

ShaderProgram.dispose

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output()

output(): null | WebGLTexture

Output image texture

Returns

null | WebGLTexture

Image texture

Inherited from

ShaderProgram.output

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prepare()

protected prepare(gl, inputs, uniforms?): void

Prepare execution of the shader

Set input textures and provided uniform values, bind program and setup vertex attribute arrays.

Parameters

• gl: WebGL2RenderingContext

Context of shader program

• inputs: (null | WebGLTexture)[]

Input image textures

• uniforms?

Values of shader uniforms

Returns

void

Inherited from

ShaderProgram.prepare

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process()

process(inputs, uniforms?): null | WebGLTexture

Process input image

Applies shader program to input image, output is written to image texture using framebuffer.

Parameters

• inputs: (null | WebGLTexture)[]

Input image textures

• uniforms?

Values of shader uniforms

Returns

null | WebGLTexture

Output image texture

Inherited from

ShaderProgram.process

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program()

program(): null | WebGLProgram

Shader program instance

Returns

null | WebGLProgram

Instance of shader program

Inherited from

ShaderProgram.program

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render()

render(inputs, uniforms?): void

Process input image and render the result

Applies shader program to input image, output is renderer to canvas providing WebGL context.

Parameters

• inputs: (null | WebGLTexture)[]

Input image textures

• uniforms?

Values of shader uniforms

Returns

void

Inherited from

ShaderProgram.render

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resize()

resize(size): void

Resize

Resizes output image texture and updates uniforms.

Parameters

• size: Size

Main/output shader size

Returns

void

Inherited from

ShaderProgram.resize

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restore()

protected restore(gl, state): void

Restore context state

Restores state of WebGL context to recorded checkpoint. This allows to safely share context with other engines.

Parameters

• gl: WebGL2RenderingContext

Context to restore state

• state

Previously recorded state

• state.activeTexture: number

• state.arrayBuffer: null | WebGLBuffer

• state.colorMask: boolean[]

• state.cullFace: boolean

• state.framebuffer: null | WebGLFramebuffer

• state.program: null | WebGLProgram

• state.scissor: Int32Array

• state.textures: (null | WebGLTexture)[]

• state.vertexArray: null | WebGLVertexArrayObject

• state.viewport: Int32Array

Returns

void

Inherited from

ShaderProgram.restore

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save()

protected save(gl): object

Save context state

Saves state of WebGL including program in use, bound array buffers, framebuffer, and textures. Returned state can be restored later to safely share context with other frameworks or renderers.

Parameters

• gl: WebGL2RenderingContext

Context which state will be recorded

Returns

object

Current state of WebGL context

activeTexture

activeTexture: number

arrayBuffer

arrayBuffer: null | WebGLBuffer

colorMask

colorMask: boolean[]

cullFace

cullFace: boolean

framebuffer

framebuffer: null | WebGLFramebuffer

program

program: null | WebGLProgram

scissor

scissor: Int32Array

textures

textures: (null | WebGLTexture)[]

vertexArray

vertexArray: null | WebGLVertexArrayObject

viewport

viewport: Int32Array

Inherited from

ShaderProgram.save

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setUniform()

setUniform(uniform, val): void

Set uniform value

Parameters

• uniform: string

Uniform name

• val: number[]

Uniform value

Returns

void

Inherited from

ShaderProgram.setUniform

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setUniformUnsafe()

protected setUniformUnsafe(uniform, val): void

Set uniform value unsafely

Parameters

• uniform: string

Uniform name

• val: number[]

Uniform value

Returns

void

Inherited from

ShaderProgram.setUniformUnsafe