Essl100.h file
ESSL 100 (OpenGL ES 2.0, "#version 100") source-to-source emitter for ShaderCompiler.
The tool lowers each ".shader" into a MODERN-GLSL stage source (in/out, texture(), "out vec4 COLOR;", std140 UBO blocks, gl_VertexID) that serves BOTH desktop GL 3.3 ("#version 330") and GLES3/WebGL2 ("#version 300 es") via runtime version injection. ESSL 100 is a different dialect; this emitter transforms an already-lowered modern-GLSL stage source into ESSL 100:
- Vertex stage: "in T name;" -> "attribute T name;" (a leading "layout(...)" is dropped — ES2 has no layout qualifier); "out T name;" -> "varying T name;".
- Fragment stage: "in T name;" -> "varying T name;"; "out vec4 COLOR;" is REMOVED and the fragment output is retargeted to gl_FragColor: "COLOR" becomes a local declared at the top of main(), each "return;" is preceded by "gl_FragColor = COLOR;" and a final "gl_FragColor = COLOR;" is appended before main()'s closing brace. ES2 has ONLY gl_FragColor (no MRT), so a fragment stage with MORE than one "out" declaration is declined with a clear diagnostic (never silently mangled).
- Both stages: "texture(" -> "texture2D(", "textureLod(" -> "texture2DLod(" (comment-aware, whole-identifier); "#ifdef GL_ES ... #endif" is unwrapped (GL_ES is always defined under "#version 100", so the fragment precision prologue becomes unconditional). A "flat" interpolation qualifier is dropped (ES2 has none).
The "#version" line is NOT emitted here (the engine injects it) — same as the modern path; ES2 wants "#version 100".
DEFERRED CONSTRUCTS (out of scope for this emitter): ES2 has neither uniform buffer objects nor gl_VertexID. A source that uses a "layout(std140)" block and/or gl_VertexID (every batched twin AND every sprite-template primary, since the template uses gl_VertexID for the corner formula and an InstanceBlock UBO) is NOT transformed — Transform() returns false with a clear diagnostic. The real transforms those need (UBO -> uniform array, gl_VertexID -> a supplied corner attribute) remain a hard problem and are intentionally not attempted here.
Namespaces
- namespace ShaderCompiler
Classes
- class ShaderCompiler::Essl100Emitter
- Transforms an already-lowered modern-GLSL stage source into ESSL 100 (OpenGL ES 2.0).