Chapter 657: GLSLNodeBuilder

Core Idea

A node builder targeting GLSL.

This module generates GLSL shader code from node materials and also generates the respective bindings and vertex buffer definitions. These data are later used by the renderer to create render and compute pipelines for render objects.

Key Concepts

• builtins : Object.<string, Array.<string>>: A dictionary that holds for each shader stage an Array of used builtins.
• extensions : Object.<string, Map.<string, Object>>: A dictionary that holds for each shader stage a Map of used extensions.
• transforms : Array.<Object.<string, (AttributeNode|string)>>: An array that holds objects defining the varying and attribute data in context of Transform Feedback.
• uniformGroups : Object.<string, Object.<string, NodeUniformsGroup>>: A dictionary holds for each shader stage ('vertex', 'fragment', 'compute') another dictionary which manages UBOs per group ('render','frame…

Reference Tables

Constructor

Signature
new GLSLNodeBuilder( object : Object3D, renderer : Renderer )

Properties

Property	Description
.builtins : Object.<string, Array.<string>>	A dictionary that holds for each shader stage an Array of used builtins.
.extensions : Object.<string, Map.<string, Object>>	A dictionary that holds for each shader stage a Map of used extensions.
`.transforms : Array.<Object.<string, (AttributeNode	string)>>`
.uniformGroups : Object.<string, Object.<string, NodeUniformsGroup>>	A dictionary holds for each shader stage ('vertex', 'fragment', 'compute') another dictionary which manages UBOs per group ('render','frame','object').

Methods

Method	Description
.buildCode()	Controls the code build of the shader stages.
.buildFunctionCode( shaderNode : ShaderNodeInternal ) : string	Builds the given shader node.
.enableExtension( name : string, behavior : string, shaderStage : string )	Enables the given extension.
.enableHardwareClipping( planeCount : string )	Enables hardware clipping.
.enableMultiview()	Enables multiview.
.generatePBO( storageArrayElementNode : StorageArrayElementNode ) : string	Setups the Pixel Buffer Object (PBO) for the given storage buffer node.
.generateTexture( texture : Texture, textureProperty : string, uvSnippet : string, depthSnippet : string, offsetSnippet : string ) : string	Generates the GLSL snippet for sampling/loading the given texture.
.generateTextureBias( texture : Texture, textureProperty : string, uvSnippet : string, biasSnippet : string, depthSnippet : string, offsetSnippet : string ) : string	Generates the GLSL snippet when sampling textures with a bias to the mip level.
.generateTextureCompare( texture : Texture, textureProperty : string, uvSnippet : string, compareSnippet : string, depthSnippet : string, offsetSnippet : string, shaderStage : string ) : string	Generates the GLSL snippet for sampling a depth texture and comparing the sampled depth values against a reference value.
.generateTextureGather( texture : Texture, textureProperty : string, uvSnippet : string, gatherSnippet : string, depthSnippet : string, offsetSnippet : string, flipYSnippet : string ) : string	Generates the GLSL snippet for gathering four texels from the given texture.
.generateTextureGatherCompare( texture : Texture, textureProperty : string, uvSnippet : string, compareSnippet : string, depthSnippet : string, offsetSnippet : string, flipYSnippet : string ) : string	Generates the GLSL snippet for performing a depth comparison on four texels in the given depth texture.
.generateTextureGrad( texture : Texture, textureProperty : string, uvSnippet : string, gradSnippet : Array.<string>, depthSnippet : string, offsetSnippet : string ) : string	Generates the GLSL snippet for sampling/loading the given texture using explicit gradients.
.generateTextureLevel( texture : Texture, textureProperty : string, uvSnippet : string, levelSnippet : string, depthSnippet : string, offsetSnippet : string ) : string	Generates the GLSL snippet when sampling textures with explicit mip level.
.generateTextureLoad( texture : Texture, textureProperty : string, uvIndexSnippet : string, levelSnippet : string, depthSnippet : string, offsetSnippet : string ) : string	Generates the GLSL snippet that reads a single texel from a texture without sampling or filtering.
.getAttributes( shaderStage : string ) : string	Returns the shader attributes of the given shader stage as a GLSL string.
.getBitcastMethod( type : string, inputType : string ) : string	Returns the bitcast method name for a given input and outputType.
.getClipDistance() : string	Returns the clip distances builtin.
.getDrawIndex() : string	Returns the draw index builtin.
.getExtensions( shaderStage : string ) : string	Returns the enabled extensions of the given shader stage as a GLSL string.
.getFloatPackingMethod( encoding : string ) : string	Returns the float packing method name for a given numeric encoding.
.getFloatUnpackingMethod( encoding : string ) : string	Returns the float unpacking method name for a given numeric encoding.
.getFragCoord() : string	Returns the frag coord builtin.
.getFragDepth() : string	Returns the frag depth builtin.
.getFrontFacing() : string	Returns the front facing builtin.
.getInstanceIndex() : string	Contextually returns either the vertex stage instance index builtin or the linearized index of an compute invocation within a grid of workgroups.
.getInvocationLocalIndex() : string	Returns a builtin representing the index of an invocation within its workgroup.
.getInvocationSubgroupIndex()	Returns a builtin representing the index of an invocation within its subgroup.
.getMethod( method : string ) : string	Returns the native shader method name for a given generic name.
.getOutputStructName() : string	Returns the output struct name. Not relevant for GLSL.
.getPropertyName( node : Node, shaderStage : string ) : string	Returns a GLSL snippet that represents the property name of the given node.
.getStructMembers( struct : StructTypeNode ) : string	Returns the members of the given struct type node as a GLSL string.
.getStructs( shaderStage : string ) : string	Returns the structs of the given shader stage as a GLSL string.
.getSubgroupIndex()	Returns a builtin representing the index of the current invocation's subgroup within its workgroup.
.getSubgroupSize()	Returns a builtin representing the size of a subgroup within the current shader.
.getTernary( condSnippet : string, ifSnippet : string, elseSnippet : string ) : string	Returns the native snippet for a ternary operation.
.getTransforms( shaderStage : string ) : string	Returns the transforms of the given shader stage as a GLSL string.
.getTypeFromAttribute( attribute : BufferAttribute ) : string	Returns the type for a given buffer attribute.
.getUniformFromNode( node : UniformNode, type : string, shaderStage : string, name : string ) : NodeUniform	This method is one of the more important ones since it's responsible for generating a matching binding instance for the given uniform node.
.getUniforms( shaderStage : string ) : string	Returns the uniforms of the given shader stage as a GLSL string.
.getVaryings( shaderStage : string ) : string	Returns the varyings of the given shader stage as a GLSL string.
.getVertexIndex() : string	Returns the vertex index builtin.
.isAvailable( name : string ) : boolean	Whether the requested feature is available or not.
.isFlipY() : boolean	Whether to flip texture data along its vertical axis or not.
.needsToWorkingColorSpace( texture : Texture ) : boolean	Checks if the given texture requires a manual conversion to the working color space.
.registerTransform( varyingName : string, attributeNode : AttributeNode )	Registers a transform in context of Transform Feedback.
.setupPBO( storageBufferNode : StorageBufferNode )	Setups the Pixel Buffer Object (PBO) for the given storage buffer node.

Key Takeaways

1. GLSLNodeBuilder extends: NodeBuilder
2. Most relevant properties: builtins, extensions, transforms, uniformGroups.
3. Key methods: buildCode, buildFunctionCode, enableExtension, enableHardwareClipping.

Connects To

• NodeBuilder: parent class
• Source: src/renderers/webgl-fallback/nodes/GLSLNodeBuilder.js