Overview
========
The Shaders Mod makes use of a deferred rendering pipeline. 
The gbuffer shaders come first in the pipeline. They render data to textures that will be sent to the composite shaders. 
Optional deferred shaders can be added between terrain and water rendering.
The composite shaders then render to textures that will be sent to the final shader. 
The final shader renders directly to the screen.

Shader Files
============
All shader files are placed in the folder "shaders" of the shader pack.
The shader source files use the name of the program in which they are to be used with extension depending on their type.

Extension  Type                 
==========================
.vsh       Vertex shader     
.gsh       Geometry shader   
.fsh       Fragment shader   

Geometry shaders need either OpenGL 3.2 with layout qualifiers or the extension GL_ARB_geometry_shader4 with configuration "maxVerticesOut".

Color Attachments
=================
The data is passed from shader to shader using color attachments. 
There are at least 4 for all machines. For machines that can support it, there are 8. 
In the deferred, composite and final shaders, these are referenced by the gcolor, gdepth, gnormal, composite, gaux1, gaux2, gaux3 and gaux4 uniforms
(colortex0 to colortex7 can be used instead of gcolor, gdepth etc.)
Despite the naming, all of these color attachments are the same and can be used for any purpose with the exception of the first two. 
The first one, gcolor has its color cleared to the current fog color before rendering. 
The second one, gdepth has its color cleared to solid white before rendering and uses a higher precision storage buffer suitable for storing depth values. 
The rest have their color cleared to black with 0 alpha.

Each color attachment uses 2 buffers (A and B) with logical names "main" and "alt", which can be used as ping-pong buffers.
When the buffers are flipped the mapping between main/alt and A/B is reversed.
Gbuffer programs always read from "main" (only gaux1-4) and write to "main" buffers (they shouldn't read and write to the same buffer at the same time).
Deferred/composite programs always read from "main" and write to "alt" buffers. 
After a deferred/composite program is rendered the buffers that it writes to are flipped so the next programs can see the current output as input.
The property "flip.<program>.<buffer>=<true|false>" can be used to enable or disable the flip independant of the buffer write.
The virtual programs "deferred_pre" and "composite_pre" can be used for buffer flipping before the deferred/composite pass.

When writing to the color attachments in the composite shader, blending is disabled. 
Writing to color attachments that the composite shader also reads from will generate artifacts (unless you just copy the original contents) 

The vertex and fragment configuration parsing is affected by the preprocessor conditional compilation directives.
The following preprocessor directives are currently recognized:
  #define <macro>
  #undef <macro>
  #ifdef <macro>
  #ifndef <macro>
  #if <int>
  #if defined <macro>
  #if !defined <macro>
  #elif <int>
  #elif defined <macro> 
  #elif !defined <macro>
  #else
  #endif

The current shaderpack can be reloaded by pressing "F3+R" or using the command "/reloadShaders". 

Shader Programs
===============
Name                         Render                                When not defined use
========================================================================================
<none>                       gui, menus                            <none>
--- Shadow map ---
shadow                       everything in shadow pass             <none>  
shadow_solid                 <not used>                            shadow
shadow_cutout                <not used>                            shadow
--- GBuffers ---
gbuffers_basic               leash, block selection box            <none>
gbuffers_textured            particles                             gbuffers_basic
gbuffers_textured_lit        lit_particles, world border           gbuffers_textured
gbuffers_skybasic            sky, horizon, stars, void             gbuffers_basic
gbuffers_skytextured         sun, moon                             gbuffers_textured
gbuffers_clouds              clouds                                gbuffers_textured
gbuffers_terrain             solid, cutout, cutout_mip             gbuffers_textured_lit
gbuffers_terrain_solid       <not used>                            gbuffers_terrain
gbuffers_terrain_cutout_mip  <not used>                            gbuffers_terrain
gbuffers_terrain_cutout      <not used>                            gbuffers_terrain
gbuffers_damagedblock        damaged_blocks                        gbuffers_terrain
gbuffers_block               block_entities                        gbuffers_terrain
gbuffers_beaconbeam          beacon beam                           gbuffers_textured
gbuffers_item                <not used>                            gbuffers_textured_lit
gbuffers_entities            entities                              gbuffers_textured_lit
gbuffers_armor_glint         glint on armor and handheld items     gbuffers_textured
gbuffers_spidereyes          eyes of spider, enderman and dragon   gbuffers_textured
gbuffers_hand                hand and opaque handheld objects      gbuffers_textured_lit
gbuffers_weather             rain, snow                            gbuffers_textured_lit
--- Deferred ---
deferred_pre                 <virtual> flip ping-pong buffers      <none>
deferred                     <deferred>                            <none>
deferred1                    <deferred>                            <none>
...
deferred15                   <deferred>                            <none>
--- GBuffers translucent ---
gbuffers_water               translucent                           gbuffers_terrain
gbuffers_hand_water          translucent handheld objects          gbuffers_hand
--- Composite ---
composite_pre                <virtual> flip ping-pong buffers      <none>
composite                    <composite>                           <none>
composite1                   <composite>                           <none>
...
composite15                  <composite>                           <none>
--- Final ---
final                        <final>                               <none>

Remarks:
 - The programs shadow_solid, shadow_cutout, gbuffers_terrain_solid, gbuffers_terrain_cutout and gbuffers_terrain_cutout_mip are not used

Todo:
 - Separate programs for world border, entities (by id, by type), cape, elytra, wolf collar, etc. 
 
Attributes
==========
Source                                          Value                                             Comment
=====================================================================================================================================================================
attribute vec3 mc_Entity;                       xy = blockId, renderType                          "blockId" is used only for blocks specified in "block.properties"      
attribute vec2 mc_midTexCoord;                  st = midTexU, midTexV                             Sprite middle UV coordinates                
attribute vec4 at_tangent;                      xyz = tangent vector, w = handedness

Uniforms
==========
Source                                          Value                                                    
=====================================================================================================================================================================
uniform int heldItemId;                         held item ID (main hand), used only for items defined in "item.properties"
uniform int heldBlockLightValue;                held item light value (main hand)
uniform int heldItemId2;                        held item ID (off hand), used only for items defined in "item.properties"
uniform int heldBlockLightValue2;               held item light value (off hand)
uniform int fogMode;                            GL_LINEAR, GL_EXP or GL_EXP2
uniform float fogDensity;                       0.0-1.0
uniform vec3 fogColor;                          r, g, b
uniform vec3 skyColor;                          r, g, b
uniform int worldTime;                          <ticks> = worldTicks % 24000
uniform int worldDay;                           <days> = worldTicks / 24000
uniform int moonPhase;                          0-7
uniform int frameCounter;                       Frame index (0 to 720719, then resets to 0)
uniform float frameTime;                        last frame time, seconds
uniform float frameTimeCounter;                 run time, seconds (resets to 0 after 3600s)
uniform float sunAngle;                         0.0-1.0
uniform float shadowAngle;                      0.0-1.0
uniform float rainStrength;                     0.0-1.0
uniform float aspectRatio;                      viewWidth / viewHeight
uniform float viewWidth;                        viewWidth
uniform float viewHeight;                       viewHeight
uniform float near;                             near viewing plane distance
uniform float far;                              far viewing plane distance
uniform vec3 sunPosition;                       sun position in eye space
uniform vec3 moonPosition;                      moon position in eye space
uniform vec3 shadowLightPosition;               shadow light (sun or moon) position in eye space
uniform vec3 upPosition;                        direction up
uniform vec3 cameraPosition;                    camera position in world space
uniform vec3 previousCameraPosition;            last frame cameraPosition
uniform mat4 gbufferModelView;                  modelview matrix after setting up the camera transformations
uniform mat4 gbufferModelViewInverse;           inverse gbufferModelView
uniform mat4 gbufferPreviousModelView;          last frame gbufferModelView
uniform mat4 gbufferProjection;                 projection matrix when the gbuffers were generated
uniform mat4 gbufferProjectionInverse;          inverse gbufferProjection
uniform mat4 gbufferPreviousProjection;         last frame gbufferProjection
uniform mat4 shadowProjection;                  projection matrix when the shadow map was generated
uniform mat4 shadowProjectionInverse;           inverse shadowProjection
uniform mat4 shadowModelView;                   modelview matrix when the shadow map was generated
uniform mat4 shadowModelViewInverse;            inverse shadowModelView
uniform float wetness;                          rainStrength smoothed with wetnessHalfLife or drynessHalfLife
uniform float eyeAltitude;                      view entity Y position
uniform ivec2 eyeBrightness;                    x = block brightness, y = sky brightness, light 0-15 = brightness 0-240 
uniform ivec2 eyeBrightnessSmooth;              eyeBrightness smoothed with eyeBrightnessHalflife
uniform ivec2 terrainTextureSize;               not used
uniform int terrainIconSize;                    not used
uniform int isEyeInWater;                       1 = camera is in water, 2 = camera is in lava
uniform float nightVision;                      night vision (0.0-1.0)
uniform float blindness;                        blindness (0.0-1.0)
uniform float screenBrightness;                 screen brightness (0.0-1.0)
uniform int hideGUI;                            GUI is hidden
uniform float centerDepthSmooth;                centerDepth smoothed with centerDepthSmoothHalflife
uniform ivec2 atlasSize;                        texture atlas size (only set when the atlas texture is bound)
uniform vec4 entityColor;                       entity color multiplier (entity hurt, creeper flashing when exploding)
uniform int entityId;                           entity ID
uniform int blockEntityId;                      block entity ID (block ID for the tile entity, only for blocks specified in "block.properties")
uniform ivec4 blendFunc;                        blend function (srcRGB, dstRGB, srcAlpha, dstAlpha)

GBuffers Uniforms
================= 
Programs: basic, textured, textured_lit, skybasic, skytextured, clouds, terrain, terrain_solid, terrain_cutout_mip, terrain_cutout, damagedblock, water, block, beaconbeam, item, entities, armor_glint, spidereyes, hand, hand_water, weather)
==================
Source                                          Value                                                    
=====================================================================================================================================================================
uniform sampler2D texture;                      0
uniform sampler2D lightmap;                     1
uniform sampler2D normals;                      2         
uniform sampler2D specular;                     3
uniform sampler2D shadow;                       waterShadowEnabled ? 5 : 4
uniform sampler2D watershadow;                  4
uniform sampler2D shadowtex0;                   4
uniform sampler2D shadowtex1;                   5
uniform sampler2D depthtex0;                    6
uniform sampler2D gaux1;                        7  <custom texture or output from deferred programs>
uniform sampler2D gaux2;                        8  <custom texture or output from deferred programs>
uniform sampler2D gaux3;                        9  <custom texture or output from deferred programs>
uniform sampler2D gaux4;                        10 <custom texture or output from deferred programs>
uniform sampler2D depthtex1;                    11
uniform sampler2D shadowcolor;                  13
uniform sampler2D shadowcolor0;                 13
uniform sampler2D shadowcolor1;                 14
uniform sampler2D noisetex;                     15

Shadow Uniforms
==================
Programs: shadow, shadow_solid, shadow_cutout 
==================
Source                                          Value                                                    
=====================================================================================================================================================================
uniform sampler2D tex;                          0
uniform sampler2D texture;                      0
uniform sampler2D lightmap;                     1
uniform sampler2D normals;                      2         
uniform sampler2D specular;                     3
uniform sampler2D shadow;                       waterShadowEnabled ? 5 : 4
uniform sampler2D watershadow;                  4
uniform sampler2D shadowtex0;                   4
uniform sampler2D shadowtex1;                   5
uniform sampler2D gaux1;                        7  <custom texture>
uniform sampler2D gaux2;                        8  <custom texture>
uniform sampler2D gaux3;                        9  <custom texture>
uniform sampler2D gaux4;                        10 <custom texture>
uniform sampler2D shadowcolor;                  13
uniform sampler2D shadowcolor0;                 13
uniform sampler2D shadowcolor1;                 14
uniform sampler2D noisetex;                     15

Composite and Deferred Uniforms
===============================
Programs: composite, composite1, composite2, composite3, composite4, composite5, composite6, composite7, final, deferred, deferred1, deferred2, deferred3, deferred4, deferred5, deferred6, deferred7
===============================
Source                                          Value                                                    
=====================================================================================================================================================================
uniform sampler2D gcolor;                       0
uniform sampler2D gdepth;                       1
uniform sampler2D gnormal;                      2
uniform sampler2D composite;                    3
uniform sampler2D gaux1;                        7
uniform sampler2D gaux2;                        8
uniform sampler2D gaux3;                        9
uniform sampler2D gaux4;                        10
uniform sampler2D colortex0;                    0
uniform sampler2D colortex1;                    1
uniform sampler2D colortex2;                    2
uniform sampler2D colortex3;                    3
uniform sampler2D colortex4;                    7
uniform sampler2D colortex5;                    8
uniform sampler2D colortex6;                    9
uniform sampler2D colortex7;                    10
uniform sampler2D shadow;                       waterShadowEnabled ? 5 : 4
uniform sampler2D watershadow;                  4
uniform sampler2D shadowtex0;                   4
uniform sampler2D shadowtex1;                   5
uniform sampler2D gdepthtex;                    6
uniform sampler2D depthtex0;                    6
uniform sampler2D depthtex1;                    11
uniform sampler2D depthtex2;                    12
uniform sampler2D shadowcolor;                  13
uniform sampler2D shadowcolor0;                 13
uniform sampler2D shadowcolor1;                 14
uniform sampler2D noisetex;                     15

GBuffers Textures
=================
Id Name           Legacy name
======================================
0  texture
1  lightmap
2  normals
3  specular
4  shadowtex0     shadow, watershadow 
5  shadowtex1     shadow (when watershadow used)
6  depthtex0
7  gaux1          <custom texture or output from deferred programs>
8  gaux2          <custom texture or output from deferred programs>
9  gaux3          <custom texture or output from deferred programs>
10 gaux4          <custom texture or output from deferred programs>
12 depthtex1
13 shadowcolor0   shadowcolor 
14 shadowcolor1
15 noisetex

Shadow Textures
==================
Id Name           Legacy name
======================================
0  texture        tex
1  lightmap
2  normals
3  specular
4  shadowtex0     shadow, watershadow        
5  shadowtex1     shadow (when watershadow used)
7  gaux1          <custom texture>
8  gaux2          <custom texture>
9  gaux3          <custom texture>
10 gaux4          <custom texture>
13 shadowcolor0   shadowcolor
14 shadowcolor1   
15 noisetex

Composite and Deferred Textures
===============================
Id Name           Legacy name
======================================
0  colortex0      gcolor 
1  colortex1      gdepth 
2  colortex2      gnormal 
3  colortex3      composite
4  shadowtex0     shadow, watershadow 
5  shadowtex1     shadow (when watershadow used)
6  depthtex0      gdepthtex
7  colortex4      gaux1
8  colortex5      gaux2
9  colortex6      gaux3
10 colortex7      gaux4
11 depthtex1
12 depthtex2
13 shadowcolor0   shadowcolor
14 shadowcolor1
15 noisetex

Depth buffers usage
===================
Name        Usage
==============================================================================
depthtex0   everything
depthtex1   no translucent objects (water, stained glass) 
depthtex2   no translucent objects (water, stained glass), no handheld objects

Shadow buffers usage
====================
Name        Usage
==============================================================================
shadowtex0  everything
shadowtex1  no translucent objects (water, stained glass) 

Vertex Shader Configuration
===========================
Source                                          Effect                                                    Comment
=====================================================================================================================================================================
attribute <type> mc_Entity;                     useEntityAttrib = true
attribute <type> mc_midTexCoord;                useMidTexCoordAttrib = true             
attribute <type> at_tangent;                    useTangentAttrib = true

Geometry Shader Configuration
===========================
Source                                          Effect                                                    Comment
=====================================================================================================================================================================
#extension GL_ARB_geometry_shader4 : enable     Enable GL_ARB_geometry_shader4
const int maxVerticesOut = 3;                   Set GEOMETRY_VERTICES_OUT_ARB for GL_ARB_geometry_shader4 

Fragment Shader Configuration
=============================
Source                                          Effect                                                     Comment
=====================================================================================================================================================================
uniform <type> shadow;                          shadowDepthBuffers = 1
uniform <type> watershadow;                     shadowDepthBuffers = 2
uniform <type> shadowtex0;                      shadowDepthBuffers = 1
uniform <type> shadowtex1;                      shadowDepthBuffers = 2
uniform <type> shadowcolor;                     shadowColorBuffers = 1
uniform <type> shadowcolor0;                    shadowColorBuffers = 1
uniform <type> shadowcolor1;                    shadowColorBuffers = 2
uniform <type> depthtex0;                       depthBuffers = 1
uniform <type> depthtex1;                       depthBuffers = 2
uniform <type> depthtex2;                       depthBuffers = 3
uniform <type> gdepth;                          if (bufferFormat[1] == RGBA) bufferFormat[1] = RGBA32F;
uniform <type> gaux1;                           colorBuffers = 5
uniform <type> gaux2;                           colorBuffers = 6
uniform <type> gaux3;                           colorBuffers = 7
uniform <type> gaux4;                           colorBuffers = 8
uniform <type> colortex4;                       colorBuffers = 5
uniform <type> colortex5;                       colorBuffers = 6
uniform <type> colortex6;                       colorBuffers = 7
uniform <type> colortex7;                       colorBuffers = 8
uniform <type> centerDepthSmooth;               centerDepthSmooth = true
/* SHADOWRES:1024 */                            shadowMapWidth = shadowMapHeight = 1024
const int shadowMapResolution = 1024;           shadowMapWidth = shadowMapHeight = 1024
/* SHADOWFOV:90.0 */                            shadowMapFov = 90
const float shadowMapFov = 90.0;                shadowMapFov = 90
/* SHADOWHPL:160.0 */                           shadowMapDistance = 160.0
const float shadowDistance = 160.0f;            shadowMapDistance = 160.0
const float shadowDistanceRenderMul = -1f;      shadowDistanceRenderMul = -1                               When > 0 enable shadow optimization (shadowRenderDistance = shadowDistance * shadowDistanceRenderMul)
const float shadowIntervalSize = 2.0f;          shadowIntervalSize = 2.0
const bool generateShadowMipmap = true;         shadowMipmap = true
const bool generateShadowColorMipmap = true;    shadowColorMipmap = true
const bool shadowHardwareFiltering = true;      shadowHardwareFiltering = true
const bool shadowHardwareFiltering0 = true;     shadowHardwareFiltering[0] = true
const bool shadowHardwareFiltering1 = true;     shadowHardwareFiltering[1] = true
const bool shadowtexMipmap = true;              shadowMipmap[0] = true
const bool shadowtex0Mipmap = true;             shadowMipmap[0] = true
const bool shadowtex1Mipmap = true;             shadowMipmap[1] = true
const bool shadowcolor0Mipmap = true;           shadowColorMipmap[0] = true
const bool shadowColor0Mipmap = true;           shadowColorMipmap[0] = true
const bool shadowcolor1Mipmap = true;           shadowColorMipmap[1] = true
const bool shadowColor1Mipmap = true;           shadowColorMipmap[1] = true
const bool shadowtexNearest = true;             shadowFilterNearest[0] = true
const bool shadowtex0Nearest = true;            shadowFilterNearest[0] = true
const bool shadow0MinMagNearest = true;         shadowFilterNearest[0] = true
const bool shadowtex1Nearest = true;            shadowFilterNearest[1] = true
const bool shadow1MinMagNearest = true;         shadowFilterNearest[1] = true
const bool shadowcolor0Nearest = true;          shadowColorFilterNearest[0] = true
const bool shadowColor0Nearest = true;          shadowColorFilterNearest[0] = true
const bool shadowColor0MinMagNearest = true;    shadowColorFilterNearest[0] = true
const bool shadowcolor1Nearest = true;          shadowColorFilterNearest[1] = true
const bool shadowColor1Nearest = true;          shadowColorFilterNearest[1] = true
const bool shadowColor1MinMagNearest = true;    shadowColorFilterNearest[1] = true
/* WETNESSHL:600.0 */                           wetnessHalfLife = 600 (ticks)
const float wetnessHalflife = 600.0f;           wetnessHalfLife = 600 (ticks)
/* DRYNESSHL:200.0 */                           drynessHalfLife = 200 (ticks)
const float drynessHalflife = 200.0f;           drynessHalfLife = 200 (ticks)
const float eyeBrightnessHalflife = 10.0f;      eyeBrightnessHalflife = 10 (ticks)
const float centerDepthHalflife = 1.0f;         centerDepthSmoothHalflife = 1 (ticks)
const float sunPathRotation = 0f;               sunPathRotation = 0f
const float ambientOcclusionLevel = 1.0f;       ambientOcclusionLevel = 1.0f                               0.0f = AO disabled, 1.0f = vanilla AO
const int superSamplingLevel = 1;               superSamplingLevel = 1
const int noiseTextureResolution = 256;         noiseTextureResolution = 256
/* GAUX4FORMAT:RGBA32F */                       buffersFormat[7] = GL_RGBA32F
/* GAUX4FORMAT:RGB32F */                        buffersFormat[7] = GL_RGB32F
/* GAUX4FORMAT:RGB16 */                         buffersFormat[7] = GL_RGB16
const int <bufferIndex>Format = <format>;       bufferFormats[index] = <format>                            See "Buffer Index" and "Texture Formats"
const bool <bufferIndex>Clear = false;          gbuffersClear[index] = false                               Skip glClear() for the given buffer, only for "composite" and "deferred" programs 
const vec4 <bufferIndex>ClearColor = vec4();    gbuffersClearColor[index] = vec4(r, g, b, a)               Clear color for the given buffer, only for "composite" and "deferred" programs 
const bool <bufferIndex>MipmapEnabled = true;   bufferMipmaps[index] = true                                Only for programs "composite" , "deferred" and "final"
/* DRAWBUFFERS:0246 */                          drawBuffers = "0246"                                       Draw buffers 0, 2, 4 and 6

Draw Buffer Index 
==================
Prefix                  Index
==================================
colortex<0-7>           0-7
gcolor                  0
gdepth                  1
gnormal                 2
composite               3
gaux1                   4
gaux2                   5
gaux3                   6
gaux4                   7
 
Texture Formats
===============
1. 8-bit normalized
 R8
 RG8
 RGB8
 RGBA8
2. 8-bit signed normalized
 R8_SNORM
 RG8_SNORM
 RGB8_SNORM
 RGBA8_SNORM
3. 16-bit normalized
 R16
 RG16
 RGB16
 RGBA16
4. 16-bit signed normalized 
 R16_SNORM
 RG16_SNORM
 RGB16_SNORM
 RGBA16_SNORM
5. 16-bit float
 R16F
 RG16F
 RGB16F
 RGBA16F
6. 32-bit float     
 R32F
 RG32F
 RGB32F
 RGBA32F
7. 32-bit integer
 R32I
 RG32I
 RGB32I
 RGBA32I
8. 32-bit unsigned integer 
 R32UI
 RG32UI
 RGB32UI
 RGBA32UI
9. Mixed
 R3_G3_B2
 RGB5_A1
 RGB10_A2
 R11F_G11F_B10F
 RGB9_E5

Block ID mapping
================
The block ID mapping is defined in "shaders/block.properties" included in the shader pack.
Forge mods may add custom block mapping as "assets/<modid>/shaders/block.properties" in the mod JAR file.
The "block.properties" file can use conditional preprocessor directives (#ifdef, #if, etc.)
For more details see section "Standard Macros" A to G. Option macros are not available.
Format "block.<id>=<block1> <block2> ..."
The key is the substitute block ID, the values are the blocks which are to be replaced.
Only one line per block ID is allowed.
See "properties_files.txt" for the block matching rules.

  # Short format
  block.31=red_flower yellow_flower reeds
  # Long format
  block.32=minecraft:red_flower ic2:nether_flower botania:reeds
  # Properties
  block.33=minecraft:red_flower:type=white_tulip minecraft:red_flower:type=pink_tulip botania:reeds:type=green

See "properties.files" for more details.

Block render layers
===================
The custom block render layers are defined in "shaders/block.properties" included in the shader pack.

  layer.solid=<blocks>
  layer.cutout=<blocks>
  layer.cutout_mipped=<blocks>
  layer.translucent=<blocks>

Layers
  solid - no alpha, no blending (solid textures)
  cutout - alpha, no blending (cutout textures)
  cutout_mipped - alpha, no blending, mipmaps (cutout with mipmaps)
  translucent - alpha, blending, mipmaps (water, stained glass)
 
Blocks which are solid opaque cubes (stone, dirt, ores, etc) can't be rendered on a custom layer
as this would affect face culling, ambient occlusion, light propagation and so on.

For exaple:
  layer.translucent=glass_pane fence wooden_door

Item ID mapping
================
The item ID mapping is defined in "shaders/item.properties" included in the shader pack.
Forge mods may add custom item mapping as "assets/<modid>/shaders/item.properties" in the mod JAR file.
The "item.properties" file can use conditional preprocessor directives (#ifdef, #if, etc.)
For more details see section "Standard Macros" A to G. Option macros are not available.
Format "item.<id>=<item1> <item2> ..."
The key is the substitute item ID, the values are the items which are to be replaced.
Only one line per item ID is allowed.

  # Short format
  item.5000=diamond_sword dirt
  # Long format
  item.5001=minecraft:diamond_sword botania:reeds

Entity ID mapping
=================
The entity ID mapping is defined in "shaders/entity.properties" included in the shader pack.
Forge mods may add custom entity mapping as "assets/<modid>/shaders/entity.properties" in the mod JAR file.
The "entity.properties" file can use conditional preprocessor directives (#ifdef, #if, etc.)
For more details see section "Standard Macros" A to G. Option macros are not available.
Format "entity.<id>=<entity1> <entity2> ..."
The key is the substitute entity ID, the values are the entities which are to be replaced.
Only one line per entity ID is allowed.

  # Short format
  entity.2000=sheep cow
  # Long format
  entity.2001=minecraft:pig botania:pixie

Standard Macros
===============
The standard macros are automatically included after the "#version" declaration in every shader file

A. Minecraft version
 #define MC_VERSION <value>
 The value is in format 122 (major 1, minor 2, release 2)
 For example: 1.9.4 -> 10904, 1.11.2 -> 11102, etc.

B. Maximum supported GL version
 #define MC_GL_VERSION <value>
 The value is integer, for example: 210, 320, 450

C. Maximum supported GLSL version
 #define MC_GLSL_VERSION <value>
 The value is integer, for example: 120, 150, 450

D. Operating system 
 One of the following:
  #define MC_OS_WINDOWS
  #define MC_OS_MAC
  #define MC_OS_LINUX
  #define MC_OS_OTHER

E. GPU
 One of the following:
  #define MC_GL_VENDOR_ATI
  #define MC_GL_VENDOR_INTEL
  #define MC_GL_VENDOR_NVIDIA
  #define MC_GL_VENDOR_XORG
  #define MC_GL_VENDOR_OTHER

F. Driver
 One of the following:
  #define MC_GL_RENDERER_RADEON 
  #define MC_GL_RENDERER_GEFORCE
  #define MC_GL_RENDERER_QUADRO
  #define MC_GL_RENDERER_INTEL
  #define MC_GL_RENDERER_GALLIUM
  #define MC_GL_RENDERER_MESA
  #define MC_GL_RENDERER_OTHER

G. OpenGL extensions
 Macros for the supported OpenGL extensions are named like the corresponding extension with a prefix "MC_".
 For example the macro "MC_GL_ARB_shader_texture_lod" is defined when the extension "GL_ARB_shader_texture_lod" is supported.
 Only the macros which are referenced and supported are added to the shader file.

H. Options
 #define MC_FXAA_LEVEL <value>       // When FXAA is enabled, values: 2, 4
 #define MC_NORMAL_MAP               // When the normal map is enabled
 #define MC_SPECULAR_MAP             // When the specular map is enabled
 #define MC_RENDER_QUALITY <value>   // Values: 0.5, 0.70710677, 1.0, 1.4142135, 2.0
 #define MC_SHADOW_QUALITY <value>   // Values: 0.5, 0.70710677, 1.0, 1.4142135, 2.0
 #define MC_HAND_DEPTH <value>       // Values: 0.0625, 0.125, 0.25
 #define MC_OLD_HAND_LIGHT           // When Old Hand Light is enabled
 #define MC_OLD_LIGHTING             // When Old Lighting is enabled

References
==========
 http://daxnitro.wikia.com/wiki/Editing_Shaders_%28Shaders2%29
 http://www.minecraftforum.net/forums/mapping-and-modding/minecraft-mods/1286604-shaders-mod-updated-by-karyonix
 http://www.minecraftforum.net/forums/search?by-author=karyonix&display-type=posts
 http://www.seas.upenn.edu/~cis565/fbo.htm#feedback
