PostProcessor

PostProcessors apply a shader effect to the entire screen at the end of the frame.

Implement PostProcessor.process: the current (MSAA-resolved) screen arrives as source and the result must be rendered into destination — typically with a ShaderPass or ShaderPipeline. Because the shape matches ShaderPipelineLike, effect objects like BloomEffect or BlurEffect can be added as post processors directly:

game.graphicsContext.addPostProcessor(new ex.BloomEffect({ graphicsContext }));

Use ShaderPipelinePostProcessor to build one from a list of fragment sources.

Fragment shaders in a ShaderPass/ShaderPipeline get these built-ins:

• uniform sampler2D u_image - the current screen (or previous pass output)
• uniform vec2 u_resolution - the destination resolution (in pixels)
• uniform vec2 u_texelSize - 1.0 / source resolution
• uniform float u_time_ms - total time in milliseconds
• uniform float u_elapsed_ms - elapsed milliseconds since the last frame
• in vec2 v_uv - 0-1 UV over the screen

The deprecated single-pass path receives u_image at slot 0 plus u_time_ms, u_elapsed_ms, and u_resolution when declared; custom uniforms can be updated in PostProcessor.onUpdate.

Implemented by

• ColorBlindnessPostProcessor
• ShaderPipelinePostProcessor

Index

Methods

• getLayout
• getShader
• initialize
• onDraw
• onUpdate
• process

Methods

optionalgetLayout

• getLayout(): VertexLayout

• @deprecated

  implement PostProcessor.process instead, the single-pass shader/layout path will be removed in v1

  ---

  Returns VertexLayout

optionalgetShader

• getShader(): Shader

• @deprecated

  implement PostProcessor.process instead, the single-pass shader/layout path will be removed in v1. The screen texture is bound to slot 0 as uniform sampler2D u_image and default uniforms (u_time_ms, u_elapsed_ms, u_resolution) are set when declared.

  ---

  Returns Shader

optionalinitialize

• initialize(graphicsContext: ExcaliburGraphicsContextWebGL): void

• Called once when the post processor is added to the graphics context

  ---

  Parameters

  • graphicsContext: ExcaliburGraphicsContextWebGL

  Returns void

optionalonDraw

• onDraw(): void

• Use the onDraw hook to upload any textures or command that need to run right before draw

  ---

  Returns void

optionalonUpdate

• onUpdate(elapsed: number): void

• Use the onUpdate hook to update any uniforms in the postprocessors shader

  The shader has already been bound so there is no need to call shader.use();

  ---

  Parameters

  • elapsed: number

  Returns void

optionalprocess

• process(source: Framebuffer, destination: Framebuffer): void

• source is the current (MSAA-resolved) screen framebuffer, render the result into destination, for example with a ShaderPass or ShaderPipeline.

  ---

  Parameters

  • source: Framebuffer

  • destination: Framebuffer

  Returns void