Gbuffers

Required stages: vertex (.vsh), fragment (.fsh)
Optional stages: geometry (.gsh), tessellation (.tcs, .tes)
Output Buffers: colortex, depthtex
Valid suffixes: N/A

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Gbuffers programs are where all the world geometry is rendered, including terrain, entities, block entities, particles, and more.

There are many buffers programs where different types of geometry are rendered. There are also fallbacks, so if a specific gbuffers file is not present the geometry that would render in that programs falls back to another program in the shader. Here’s a table which shows each program, it’s fallback, and the geometry it’s responsible for (this list is not in order):

gbuffers program	geometry	fallback program
gbuffers_basic	leash, debug chunk border overlay	N/A
gbuffers_line	block outline, fishing line	gbuffers_basic
gbuffers_textured	world border, particles that don’t support lighting	gbuffers_basic
gbuffers_textured_lit	particles that support lighting (most particles)	gbuffers_textured
gbuffers_skybasic	sky color/horizon, stars, void	gbuffers_basic
gbuffers_skytextured	sun and moon textures	gbuffers_textured
gbuffers_clouds	vanilla clouds	gbuffers_textured
gbuffers_terrain	static blocks	gbuffers_textured_lit
gbuffers_damagedblock	block breaking texture	gbuffers_terrain
gbuffers_block	block entities, sign text	gbuffers_terrain
gbuffers_beaconbeam	beacon beam	gbuffers_textured
gbuffers_entities	entities, nametag text	gbuffers_textured_lit
gbuffers_armor_glint	enchantment effect on items/armor	gbuffers_textured
gbuffers_spidereyes	spider/enderman/dragon eyes	gbuffers_textured
gbuffers_hand	player hand and handheld objects	gbuffers_textured_lit
gbuffers_weather	falling rain/snow, doesn’t include particles	gbuffers_textured_lit
gbuffers_water	translucent terrain (including water)	gbuffers_terrain
gbuffers_hand_water	translucent handheld objects	gbuffers_hand

Note: In Optifine gbuffers_entities_glowing renders entities that have the spectral effect (but does not impact the outline itself). This shader file is not recognized in Iris.

Iris Additional Programs

The following programs are added by Iris. These programs pull geometry from their fallback, and provide more specificity to the geometry rendered. They also serve to separate translucent geometry that would otherwise render in the same program as opaque geometry, which should be used with ENTITY_TRANSLUCENT.

gbuffers program	geometry	fallback program
gbuffers_particles	particles	gbuffers_textured_lit
gbuffers_particles_translucent	particles that support translucency (requires particles.ordering=mixed)	gbuffers_particles
gbuffers_block_translucent	translucent block entities	gbuffers_block
gbuffers_entities_translucent	translucent entities	gbuffers_entities
gbuffers_terrain_solid	solid terrain (no cutout or translucency)	gbuffers_terrain
gbuffers_terrain_cutout	cutout terrain (no solid or translucency)	gbuffers_terrain
gbuffers_lightning	lightning, ender dragon death beams	gbuffers_entities

Translucent Gbuffers and Deferred

The general concept behind the deferred pass is that opaque geometry is rendered before deferred and translucent geometry is rendered after deferred. The intent is that the deferred programs can handle deferred rendering for opaque geometry, and translucent geometry can either be forward rendered in gbuffers or deferred rendered separately from opaques in a composite program.

In practice, using the old Optifine programs this was not always the case though. By default,gbuffers_weather, gbuffers_water, and gbuffers_hand_water are the only programs that render after deferred, meaning that translucent entities, block entities, and particles were all rendered before deferred. This is why Iris adds gbuffers_particles_translucent, gbuffers_block_translucent, and gbuffers_entities_translucent, and uses particles.ordering to handle the order particles are rendered.

Notes on specific geometry

• the ender dragon death beans write their color in gbuffers_lightning, however the depth is written in gbuffers_basic