{"id":14201,"date":"2024-10-21T00:25:14","date_gmt":"2024-10-21T04:25:14","guid":{"rendered":"https:\/\/www.sceneri.com\/?post_type=sceneri-pro-docs&#038;p=14201"},"modified":"2024-11-01T23:42:18","modified_gmt":"2024-11-02T03:42:18","slug":"visual-scripting-backend","status":"publish","type":"sceneri-pro-docs","link":"https:\/\/www.sceneri.com\/sceneri-pro-docs\/introduction\/logic-graph\/visual-scripting-backend\/","title":{"rendered":"Visual Scripting Backend"},"content":{"rendered":"<div class=\"fusion-fullwidth fullwidth-box fusion-builder-row-1 fusion-flex-container has-pattern-background has-mask-background hundred-percent-fullwidth non-hundred-percent-height-scrolling\" style=\"--awb-border-radius-top-left:0px;--awb-border-radius-top-right:0px;--awb-border-radius-bottom-right:0px;--awb-border-radius-bottom-left:0px;--awb-padding-right:0px;--awb-padding-left:0px;--awb-flex-wrap:wrap;\" ><div class=\"fusion-builder-row fusion-row fusion-flex-align-items-flex-start fusion-flex-content-wrap\" style=\"width:104% !important;max-width:104% !important;margin-left: calc(-4% \/ 2 );margin-right: calc(-4% \/ 2 );\"><div class=\"fusion-layout-column fusion_builder_column fusion-builder-column-0 fusion_builder_column_1_1 1_1 fusion-flex-column\" style=\"--awb-bg-size:cover;--awb-width-large:100%;--awb-margin-top-large:0px;--awb-spacing-right-large:1.92%;--awb-margin-bottom-large:20px;--awb-spacing-left-large:1.92%;--awb-width-medium:100%;--awb-order-medium:0;--awb-spacing-right-medium:1.92%;--awb-spacing-left-medium:1.92%;--awb-width-small:100%;--awb-order-small:0;--awb-spacing-right-small:1.92%;--awb-spacing-left-small:1.92%;\" data-scroll-devices=\"small-visibility,medium-visibility,large-visibility\"><div class=\"fusion-column-wrapper fusion-column-has-shadow fusion-flex-justify-content-flex-start fusion-content-layout-column\"><div class=\"fusion-text fusion-text-1\" style=\"--awb-text-font-family:&quot;Inter&quot;;--awb-text-font-style:normal;--awb-text-font-weight:200;\"><h3 class=\"ql-heading\" data-block-id=\"block-090a65b7-0a6a-4979-9588-b1ef280a7573\">Overview<\/h3>\n<div class=\"ql-block\" data-block-id=\"block-65501c86-7f1d-448f-b591-25cae0e6fbe0\">Visual scripting is implemented in 4 parts:<\/div>\n<ul>\n<li>Parser <code>\\Code\\Common\\Public\\Common\\Scripting\\Parser<\/code><\/li>\n<li>Interpreter <code>\\Code\\Common\\Public\\Common\\Scripting\\Interpreter<\/code><\/li>\n<li>Compiler <code>\\Code\\Common\\Public\\Common\\Scripting\\Compiler<\/code><\/li>\n<li>Virtual Machine <code>\\Code\\Common\\Public\\Common\\Scripting\\VirtualMachine<\/code><\/li>\n<\/ul>\n<div class=\"ql-block\" data-block-id=\"block-785b5a54-67a8-439a-9cfb-1548fff645d8\"><\/div>\n<div class=\"ql-block\" data-block-id=\"block-53162d61-adeb-4d79-8532-a6820bbb8241\">Our Sceneri script asset type is<\/div>\n<ul>\n<li><code>.script.source<\/code> for the text source file (we use LUA syntax for now)<\/li>\n<li><code>.script.binary<\/code> compiled binary format of <code>.script.source<\/code><\/li>\n<\/ul>\n<div class=\"ql-block\" data-block-id=\"block-f5b0487f-5edf-4395-83a5-28d2a727ccb8\">Compilation of script files is done through the asset compiler which produces these two files.<\/div>\n<h3 class=\"ql-heading\" data-block-id=\"block-4fbb8a14-d3e1-4f0c-8c8d-c5ec1710ee65\">Compilation Options<\/h3>\n<ul>\n<li><code>SCRIPTING_USE_UNICODE<\/code><\/li>\n<\/ul>\n<div class=\"ql-block ql-indent-1\" data-block-id=\"block-4f7d1467-ff4a-40e0-9b1e-8e35ed497a49\">Switches between <code>ngine::String<\/code> and <code>ngine::UnicodeString<\/code> as script string type<\/div>\n<div class=\"ql-block ql-indent-1\" data-block-id=\"block-581af7dc-3d13-42eb-8060-67c333f99d89\"><em>Default<\/em>: <strong>Disabled <\/strong>because we prefer strings as long as we don&#8217;t need to support unicode<\/div>\n<ul>\n<li><code>SCRIPTING_DEBUG_INFO<\/code><\/li>\n<\/ul>\n<ul>\n<li data-list=\"none\">Enables additional debug information in the compiled byte code. For now this is only line numbers.<\/li>\n<li data-list=\"none\"><em>Default<\/em>: <strong>Enabled <\/strong>for now, since we are still in development (should be disabled for release)<\/li>\n<\/ul>\n<ul>\n<li><code>SCRIPTING_DEBUG_TRACE_EXECUTION<\/code><\/li>\n<\/ul>\n<ul>\n<li data-list=\"none\">Enables virtual machine opcode execution tracing. Giving detailed output of each executed instruction with the current stack and upvalues.<\/li>\n<li data-list=\"none\"><em>Default<\/em>: <strong>Disabled <\/strong>should only be used when debugging VM execution bugs<\/li>\n<\/ul>\n<ul>\n<li><code>SCRIPTING_DEBUG_GC_LOG<\/code><\/li>\n<\/ul>\n<ul>\n<li data-list=\"none\">Enables detailed log output for the script garbage collection<\/li>\n<li data-list=\"none\"><em>Default<\/em>: <strong>Disabled <\/strong>should only be used when debugging VM garbage collection bugs<\/li>\n<\/ul>\n<ul>\n<li><code>SCRIPTING_VALUE_NAN_BOXING<\/code><\/li>\n<\/ul>\n<ul>\n<li data-list=\"none\">Enables nan boxing for compiled script values. This reduces the <code>ngine::Scripting::Value<\/code> size from 16 bytes to 8 bytes.<\/li>\n<li data-list=\"none\"><em>Default<\/em>: <strong>Disabled <\/strong>because runtime cost seems higher with the memory saving.<\/li>\n<\/ul>\n<ul>\n<li><code>SCRIPTING_COMPONENT_USE_INTERPRETER<\/code><\/li>\n<\/ul>\n<ul>\n<li data-list=\"none\">Switches the script component to use AST interpretation instead of executing compiled code<\/li>\n<li data-list=\"none\"><em>Default<\/em>: <strong>Disabled <\/strong>because we prefer compiled code execution (optimized, smaller, faster)<\/li>\n<\/ul>\n<h3 class=\"ql-heading\" data-block-id=\"block-f0d33abe-b3ec-49ea-bea0-fe18cef7ac77\">Parser<\/h3>\n<div class=\"ql-block\" data-block-id=\"block-832fbc76-c4e4-4d6b-bb07-56b8fbe387e4\">The parser is a simple RD (Recursive Descent) parser which follows the LUA language syntax from <a class=\"ql-link\" href=\"https:\/\/www.lua.org\/manual\/5.4\/manual.html#9\" target=\"_blank\" rel=\"noopener noreferrer\">Lua 5.4 Reference Manual<\/a><\/div>\n<div class=\"ql-block\" data-block-id=\"block-5d4a337a-cc99-408c-9976-583e6cad5b96\">It takes the output from the Lexer (tokenizer) <code>ngine::Scripting::TokenListType<\/code> and (if successful) produces a complete AST with the root node <code>UniquePtr<\/code><\/div>\n<h3 class=\"ql-heading\" data-block-id=\"block-6b5bdcc1-d0d3-440c-b1ec-0e93ab2b0779\">Interpreter<\/h3>\n<div class=\"ql-block\" data-block-id=\"block-78a87b56-9a4b-466b-9000-16479a747f6b\">The interpreter takes the output of the parser <code>UniquePtr<\/code> and executes it by walking and interpreting the AST directly. This uses its own environment <code>ngine::Scripting::Environment<\/code> . For the execution a separate input ( <code>SharedPtr<\/code> ) of resolved variables is needed which can be generated from the Resolver <code>ngine::Scripting::Resolver<\/code> . The interpreter is exposed to the editor as a script component if interpretation is enabled and compiled in via <code>SCRIPTING_COMPONENT_USE_INTERPRETER<\/code><\/div>\n<h4 class=\"ql-heading\" data-block-id=\"block-db33f33c-5f81-400b-ab23-b18644d080ed\">Exposing of native functions<\/h4>\n<div class=\"ql-block\" data-block-id=\"block-e08e7d23-9997-4312-b13b-39207b9c7b48\">Create a native function class wrapper by implementing <code>ngine::Scripting::ScriptFunction<\/code><\/div>\n<div class=\"ql-block\" data-block-id=\"block-c2aac6c9-017a-4841-812b-406a97b0dd06\">This requires overwriting of <code>GetArity()<\/code> which should return the required amount of arguments and <code>Call<\/code> for the actual function implementation. Values can be marshalled (in both directions) through <code>ngine::Scripting::Interpreter::Convert<\/code> . It can be added to the environment via <code>AddFunction(SCRIPT_STRING_LITERAL(\"name\"), UniquePtr::Make())<\/code><\/div>\n<h3 class=\"ql-heading\" data-block-id=\"block-dc66db1b-e438-421e-a366-2ce39d16a178\">Compiler<\/h3>\n<div class=\"ql-block\" data-block-id=\"block-419a0e37-00a4-48ef-9595-5978cb287138\">The compiler takes the output of the parser <code>UniquePtr<\/code> and generates self contained byte code <code>UniquePtr<\/code> that can be executed by the virtual machine<\/div>\n<h3 class=\"ql-heading\" data-block-id=\"block-69873d93-cff3-4465-a9f1-1b4a199e0537\">Virtual Machine<\/h3>\n<div class=\"ql-block\" data-block-id=\"block-d7af8037-0697-495e-8b0c-3648c04e9796\">The virtual machine takes the output of the compiler <code>UniquePtr<\/code> and executes it. As environment table it uses the <code>ngine::Scripting::EnvironmentObject<\/code> which can be used to inject external values and functions.<\/div>\n<h4 class=\"ql-heading\" data-block-id=\"block-41501af8-36b0-47d0-ad89-41e003cbe994\">Exposing of native functions<\/h4>\n<div class=\"ql-block\" data-block-id=\"block-b16e30e1-b0bd-4fb8-8952-398de34253f2\">To expose a native function it needs a thin wrapper function with following signature:<\/div>\n<div class=\"ql-block\" data-block-id=\"block-b2912b59-fef3-401d-87e4-6571cec14645\"><code>bool MyFunction(ngine::Scripting::VMState&amp; state, uint8, ngine::Scripting::Value* pArgs)<\/code><\/div>\n<div class=\"ql-block\" data-block-id=\"block-e6001559-c60d-44f9-8af5-116dba5fce78\">Values can be marshalled (in both directions) through <code>ngine::Scripting::Convert<\/code> . It can be added to the environment via <code>ngine::Scripting::AddNativeFunctionToTable<\/code><\/div>\n<\/div><\/div><\/div><\/div><\/div>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":251212454,"featured_media":0,"parent":16077,"menu_order":0,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"sceneri-docs-tag":[],"class_list":["post-14201","sceneri-pro-docs","type-sceneri-pro-docs","status-publish","format-standard","hentry"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v23.8 (Yoast SEO v23.8) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Visual Scripting Backend - Sceneri<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.sceneri.com\/sceneri-pro-docs\/introduction\/logic-graph\/visual-scripting-backend\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Visual Scripting Backend\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.sceneri.com\/sceneri-pro-docs\/introduction\/logic-graph\/visual-scripting-backend\/\" \/>\n<meta property=\"og:site_name\" content=\"Sceneri\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/sceneriapp\" \/>\n<meta property=\"article:modified_time\" content=\"2024-11-02T03:42:18+00:00\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:site\" content=\"@sceneriapp\" \/>\n<meta name=\"twitter:label1\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.sceneri.com\/sceneri-pro-docs\/introduction\/logic-graph\/visual-scripting-backend\/\",\"url\":\"https:\/\/www.sceneri.com\/sceneri-pro-docs\/introduction\/logic-graph\/visual-scripting-backend\/\",\"name\":\"Visual Scripting Backend - 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