VPFX Uniform Reference

This document describes the current public VPFX built-in uniforms available to VPFX pack shaders.

This reference is based on the current implementation of:

VpfxBuiltinUniformBuffer
VpfxBuiltinUniformSourceInjector
VpfxFrameProjectionState
VpfxFrameEnvironmentState
VpfxNativeFrameGraphPipelineCache
VpfxNativeFrameGraphExecutor

The main public uniform block is:

layout(std140) uniform VpfxBuiltins

VPFX automatically injects this block into .vsh and .fsh shader entry files unless the shader already declares it.

---

1. Scope of this document

This document covers uniforms available to external VPFX post-effect / fullscreen shaderpack passes.

It covers:

Time uniforms
Frame size uniforms
Camera position
Projection matrices
View rotation matrices
Scene depth reconstruction helpers
Fog and sky uniforms
Sun, moon, and shadow light direction helpers
Shadow matrix uniforms
Shadow map size and bias
Iris-style aliases currently provided by VPFX

It does not fully document the internal terrain receiver uniform block:

VpfxTerrainShadow

VpfxTerrainShadow is used internally by VPFX terrain shadow receiver shaders. External post-effect packs should use VpfxBuiltins unless a future API explicitly exposes additional terrain-shadow-specific blocks.

---

2. Automatic injection

VPFX preprocesses user shaders in this order:

1. Expand #include directives.
2. Inject VPFX built-in uniform declarations.

The built-in uniform block is injected into:

.vsh
.fsh

It is not injected into:

.glsl include files

This prevents duplicate uniform block declarations when includes are reused by multiple shaders.

---

3. How to use built-in uniforms

In most shaders, you do not need to declare VpfxBuiltins manually.

You can directly use the provided macros:

#version 150

uniform sampler2D InSampler;

in vec2 texCoord;
out vec4 fragColor;

void main() {
    vec3 color = texture(InSampler, texCoord).rgb;

    float pulse = 0.5 + 0.5 * sin(vpfx_Time);
    color *= mix(0.9, 1.1, pulse);

    fragColor = vec4(color, 1.0);
}

VPFX injects the required uniform block after the #version line.

---

4. Do not redeclare built-ins unless necessary

The injector skips injection if the shader source already contains one of these:

VPFX_BUILTIN_UNIFORMS
layout(std140) uniform VpfxBuiltins
uniform VpfxBuiltins

For normal pack authoring, do not write your own VpfxBuiltins block. Use the injected one.

Manual redeclaration can break if the runtime layout changes.

---

5. Full current GLSL block

The current injected block is:

#ifndef VPFX_BUILTIN_UNIFORMS
#define VPFX_BUILTIN_UNIFORMS

layout(std140) uniform VpfxBuiltins {
    vec4 vpfx_TimeInfo;
    vec4 vpfx_ViewInfo;
    vec4 vpfx_SceneInfo;
    vec4 vpfx_ShadowInfo;
    vec4 vpfx_FogColorInfo;
    vec4 vpfx_FogDistanceInfoA;
    vec4 vpfx_FogDistanceInfoB;
    vec4 vpfx_SkyColorInfo;
    vec4 vpfx_CelestialAngleInfo;
    vec4 vpfx_SunPositionInfo;
    vec4 vpfx_MoonPositionInfo;
    vec4 vpfx_ShadowLightPositionInfo;
    vec4 vpfx_UpPositionInfo;
    mat4 gbufferProjection;
    mat4 vpfx_InverseProjectionMatrix;
    mat4 gbufferPreviousProjection;
    mat4 vpfx_PreviousInverseProjectionMatrix;
    mat4 gbufferModelView;
    mat4 vpfx_InverseViewRotationMatrix;
    mat4 gbufferPreviousModelView;
    mat4 vpfx_PreviousInverseViewRotationMatrix;
    mat4 vpfx_ViewProjectionMatrix;
    mat4 vpfx_InverseViewProjectionMatrix;
    mat4 shadowModelView;
    mat4 vpfx_InverseShadowViewMatrix;
    mat4 shadowProjection;
    mat4 vpfx_InverseShadowProjectionMatrix;
    mat4 vpfx_ShadowViewProjectionMatrix;
};

#endif

The block uses std140 layout.

Current CPU-side layout size:

13 vec4 + 15 mat4
1168 bytes

Pack authors normally do not need to care about the byte layout unless debugging GPU binding problems.

---

6. Time uniforms

Raw field:

vec4 vpfx_TimeInfo;

Macros:

#define vpfx_Time       (vpfx_TimeInfo.x)
#define vpfx_DeltaTime  (vpfx_TimeInfo.y)
#define vpfx_GameTime   (vpfx_TimeInfo.z)
#define vpfx_FrameIndex (vpfx_TimeInfo.w)

Macro	Type	Meaning
vpfx_Time	float	Accumulated runtime time in seconds.
vpfx_DeltaTime	float	Delta time in seconds for the current VPFX frame.
vpfx_GameTime	float	World game time in seconds when a world is loaded.
vpfx_FrameIndex	float	Incrementing frame counter stored as a float.

Example:

float wave = 0.5 + 0.5 * sin(vpfx_Time * 2.0);

Use cases:

animated color grading
debug flashing
temporal noise phase
simple time-based effects

---

7. View and weather uniforms

Raw field:

vec4 vpfx_ViewInfo;

Macros:

#define vpfx_CameraPos    (vpfx_ViewInfo.xyz)
#define vpfx_RainStrength (vpfx_ViewInfo.w)

Macro	Type	Meaning
vpfx_CameraPos	vec3	Current camera/world position used by VPFX built-ins.
vpfx_RainStrength	float	Rain level, usually in [0, 1].

Example:

float wetLook = smoothstep(0.2, 1.0, vpfx_RainStrength);

Important note:

vpfx_CameraPos is for main-scene reconstruction and general world-position effects. Do not use camera view direction to decide shadow direction. VPFX shadow direction is based on the selected light direction and shadow matrices, not the player look direction.

---

8. View size uniforms

Raw field:

vec4 vpfx_SceneInfo;

Macros:

#define vpfx_ViewSize    (vpfx_SceneInfo.xy)
#define vpfx_InvViewSize (vpfx_SceneInfo.zw)

Macro	Type	Meaning
vpfx_ViewSize	vec2	Framebuffer width and height.
vpfx_InvViewSize	vec2	1.0 / width, 1.0 / height.

Example:

vec2 texel = vpfx_InvViewSize;
vec3 left = texture(InSampler, texCoord - vec2(texel.x, 0.0)).rgb;
vec3 right = texture(InSampler, texCoord + vec2(texel.x, 0.0)).rgb;

Use cases:

blur kernels
edge detection
pixel offsets
resolution-independent effects

---

9. Depth and shadow info uniforms

Raw field:

vec4 vpfx_ShadowInfo;

Macros:

#define vpfx_ZNear         (vpfx_ShadowInfo.x)
#define vpfx_ZFar          (vpfx_ShadowInfo.y)
#define vpfx_ShadowMapSize (vpfx_ShadowInfo.z)
#define vpfx_ShadowBias    (vpfx_ShadowInfo.w)

Macro	Type	Meaning
vpfx_ZNear	float	Main camera near plane.
vpfx_ZFar	float	Main camera far plane.
vpfx_ShadowMapSize	float	Current VPFX shadow map size. 0.0 when unavailable.
vpfx_ShadowBias	float	Current built-in shadow bias value.

Example:

bool hasShadowMap = vpfx_ShadowMapSize > 0.5;
vec2 shadowTexel = hasShadowMap ? vec2(1.0 / vpfx_ShadowMapSize) : vec2(0.0);

Important:

vpfx_ShadowMapSize > 0.0 only means a shadow target size is known. It does not by itself guarantee that a pack is correctly applying shadow_depth.

---

10. Fog color uniforms

Raw field:

vec4 vpfx_FogColorInfo;

Macro:

#define vpfx_FogColor (vpfx_FogColorInfo)

Alias:

#define fogColor (vpfx_FogColor.rgb)

Macro	Type	Meaning
vpfx_FogColor	vec4	Current fog color.
fogColor	vec3	Iris-style alias for fog RGB.

Example:

vec3 fogTint = fogColor;

---

11. Fog distance uniforms

Raw fields:

vec4 vpfx_FogDistanceInfoA;
vec4 vpfx_FogDistanceInfoB;

Macros:

#define vpfx_FogStart    (vpfx_FogDistanceInfoA.x)
#define vpfx_FogEnd      (vpfx_FogDistanceInfoA.y)
#define vpfx_SkyFogEnd   (vpfx_FogDistanceInfoB.x)
#define vpfx_CloudFogEnd (vpfx_FogDistanceInfoB.y)
#define vpfx_FogKind     (vpfx_FogDistanceInfoB.z)

Aliases:

#define fogStart (vpfx_FogStart)
#define fogEnd   (vpfx_FogEnd)

Macro	Type	Meaning
vpfx_FogStart	float	Fog start distance.
vpfx_FogEnd	float	Fog end distance.
vpfx_SkyFogEnd	float	Sky fog end distance.
vpfx_CloudFogEnd	float	Cloud fog end distance.
vpfx_FogKind	float	Numeric fog kind value from runtime state.

Use cases:

fog-aware color grading
distance haze
debug fog views
dimension-specific atmosphere tuning

---

12. Sky color and day state

Raw field:

vec4 vpfx_SkyColorInfo;

Macros:

#define vpfx_SkyColor (vpfx_SkyColorInfo.rgb)
#define vpfx_IsDay    (vpfx_SkyColorInfo.w > 0.5)

Alias:

#define skyColor (vpfx_SkyColor)

Macro	Type	Meaning
vpfx_SkyColor	vec3	Current sky color.
vpfx_IsDay	bool expression	Whether VPFX considers the current primary light to be day/sun-based.
skyColor	vec3	Iris-style alias.

Example:

vec3 dayTone = vpfx_IsDay ? vec3(1.0, 0.98, 0.92) : vec3(0.75, 0.82, 1.0);

---

13. Celestial angle uniforms

Raw field:

vec4 vpfx_CelestialAngleInfo;

Macros:

#define vpfx_SunAngle    (vpfx_CelestialAngleInfo.x)
#define vpfx_MoonAngle   (vpfx_CelestialAngleInfo.y)
#define vpfx_ShadowAngle (vpfx_CelestialAngleInfo.z)

Aliases:

#define sunAngle    (vpfx_SunAngle)
#define moonAngle   (vpfx_MoonAngle)
#define shadowAngle (vpfx_ShadowAngle)

Macro	Type	Meaning
vpfx_SunAngle	float	Sun angle value from environment state.
vpfx_MoonAngle	float	Moon angle value from environment state.
vpfx_ShadowAngle	float	VPFX shadow angle value.

Use these for broad time-of-day effects.

Example:

float sunsetBoost = smoothstep(0.20, 0.30, vpfx_SunAngle) *
                    (1.0 - smoothstep(0.32, 0.42, vpfx_SunAngle));

---

14. Sun, moon, shadow light, and up vectors

Raw fields:

vec4 vpfx_SunPositionInfo;
vec4 vpfx_MoonPositionInfo;
vec4 vpfx_ShadowLightPositionInfo;
vec4 vpfx_UpPositionInfo;

Macros:

#define vpfx_SunPosition         (vpfx_SunPositionInfo.xyz)
#define vpfx_MoonPosition        (vpfx_MoonPositionInfo.xyz)
#define vpfx_ShadowLightPosition (vpfx_ShadowLightPositionInfo.xyz)
#define vpfx_UpPosition          (vpfx_UpPositionInfo.xyz)

Aliases:

#define sunPosition         (vpfx_SunPosition)
#define moonPosition        (vpfx_MoonPosition)
#define shadowLightPosition (vpfx_ShadowLightPosition)
#define upPosition          (vpfx_UpPosition)

Macro	Type	Meaning
vpfx_SunPosition	vec3	Sun direction-like vector transformed into view space and scaled.
vpfx_MoonPosition	vec3	Moon direction-like vector transformed into view space and scaled.
vpfx_ShadowLightPosition	vec3	Current selected shadow light vector: sun during day, moon during night.
vpfx_UpPosition	vec3	View-space up vector scaled by runtime.

Important:

These are direction-like helper vectors, not physical world coordinates of a real sun object.

Example:

vec3 lightDirView = normalize(vpfx_ShadowLightPosition);

Use cases:

light-aware tone mapping
day/night color grading
debug visualizations
simple directional post effects

---

15. Projection matrices

Raw matrices:

mat4 gbufferProjection;
mat4 vpfx_InverseProjectionMatrix;
mat4 gbufferPreviousProjection;
mat4 vpfx_PreviousInverseProjectionMatrix;

Macros and aliases:

#define vpfx_ProjectionMatrix         (gbufferProjection)
#define vpfx_PreviousProjectionMatrix (gbufferPreviousProjection)

#define gbufferProjectionInverse         (vpfx_InverseProjectionMatrix)
#define gbufferPreviousProjectionInverse (vpfx_PreviousInverseProjectionMatrix)

Name	Type	Meaning
vpfx_ProjectionMatrix	mat4	Current main camera projection matrix.
vpfx_InverseProjectionMatrix	mat4	Inverse of current main camera projection matrix.
vpfx_PreviousProjectionMatrix	mat4	Previous main camera projection matrix.
vpfx_PreviousInverseProjectionMatrix	mat4	Previous inverse main camera projection matrix.

Use cases:

scene depth reconstruction
view-space position reconstruction
temporal effects
debug views

---

16. View rotation matrices

Raw matrices:

mat4 gbufferModelView;
mat4 vpfx_InverseViewRotationMatrix;
mat4 gbufferPreviousModelView;
mat4 vpfx_PreviousInverseViewRotationMatrix;

Macros and aliases:

#define vpfx_ViewRotationMatrix         (gbufferModelView)
#define vpfx_PreviousViewRotationMatrix (gbufferPreviousModelView)

#define gbufferModelViewInverse         (vpfx_InverseViewRotationMatrix)
#define gbufferPreviousModelViewInverse (vpfx_PreviousInverseViewRotationMatrix)

Important:

gbufferModelView in VPFX post-effect shaders is a camera-relative rotation matrix. It does not include a full world translation.

This differs from a full model-view matrix used during normal geometry rendering.

Use cases:

rotating reconstructed view-space directions into world-relative directions
scene depth reconstruction helpers
view-aware debug effects

---

17. View-projection matrices

Raw matrices:

mat4 vpfx_ViewProjectionMatrix;
mat4 vpfx_InverseViewProjectionMatrix;

Name	Type	Meaning
vpfx_ViewProjectionMatrix	mat4	Current projection * view-rotation matrix.
vpfx_InverseViewProjectionMatrix	mat4	Inverse of current view-projection matrix.

These are used by VPFX helper functions to reconstruct world-space positions from raw scene depth.

Important:

The reconstructed world position uses vpfx_CameraPos to restore world translation.

---

18. Shadow matrices

Raw matrices:

mat4 shadowModelView;
mat4 vpfx_InverseShadowViewMatrix;
mat4 shadowProjection;
mat4 vpfx_InverseShadowProjectionMatrix;
mat4 vpfx_ShadowViewProjectionMatrix;

Macros and aliases:

#define vpfx_ShadowViewMatrix       (shadowModelView)
#define vpfx_ShadowProjectionMatrix (shadowProjection)

#define shadowModelViewInverse      (vpfx_InverseShadowViewMatrix)
#define shadowProjectionInverse     (vpfx_InverseShadowProjectionMatrix)
#define shadowViewProjection        (vpfx_ShadowViewProjectionMatrix)

Name	Type	Meaning
vpfx_ShadowViewMatrix	mat4	Current VPFX shadow view matrix.
vpfx_InverseShadowViewMatrix	mat4	Inverse shadow view matrix.
vpfx_ShadowProjectionMatrix	mat4	Current VPFX shadow projection matrix.
vpfx_InverseShadowProjectionMatrix	mat4	Inverse shadow projection matrix.
vpfx_ShadowViewProjectionMatrix	mat4	shadowProjection * shadowModelView.

Important:

VPFX shadow matrices are based on the selected light direction and stable shadow-space rules. They must not be treated as the player camera view matrix.

Current limitation:

The public VpfxBuiltins block currently exposes shadow matrices, shadow map size, and shadow bias, but it does not expose shadowOrigin as a public post-effect uniform.

Because the internal shadow caster and terrain receiver use worldPos - shadowOrigin, external packs should not assume they can fully reconstruct shadow-map UVs from scene_depth using only vpfx_WorldPositionFromRaw and vpfx_ShadowViewProjectionMatrix.

For now:

shadow_depth is safe for debug display.
shadow_depth can be sampled directly as a texture.
full custom terrain shadow receiver logic should wait for a public shadowOrigin uniform.

A later shadow_depth guide should document this more deeply.

---

19. Scene depth reconstruction helpers

VPFX injects two helper functions.

19.1 vpfx_ViewPositionFromRaw

vec3 vpfx_ViewPositionFromRaw(sampler2D depthSampler, vec2 uv)

This reconstructs a view-space position from raw scene depth.

Example:

vec3 viewPos = vpfx_ViewPositionFromRaw(DepthSampler, texCoord);

Use cases:

depth debug
distance fog
view-space effects
depth-based edge detection

---

19.2 vpfx_WorldPositionFromRaw

vec3 vpfx_WorldPositionFromRaw(sampler2D depthSampler, vec2 uv)

This reconstructs a world-space position from raw scene depth.

Implementation concept:

raw scene depth
-> clip position
-> inverse view-projection
-> camera position added back

Example:

vec3 worldPos = vpfx_WorldPositionFromRaw(DepthSampler, texCoord);

Use cases:

world-height fog
distance-based color grading
debug world-position views

Important:

This helper reconstructs main-camera world position. It does not automatically convert positions into VPFX shadow-origin-relative coordinates.

---

20. Safe denominator helper

VPFX also injects:

float vpfx_InternalSafeSignedDenominator(float value)

This is an internal helper used by the reconstruction functions.

Pack authors normally do not need to call it directly.

---

21. Example: scene depth debug view

pack.json should enable scene depth:

"capabilities": {
  "scene_color": true,
  "scene_depth": true,
  "shadow_depth": false,
  "custom_targets": true,
  "compute": false
}

Graph input:

{
  "sampler_name": "Depth",
  "target": "vulkanpostfx:scene_depth"
}

Fragment shader:

#version 150

uniform sampler2D DepthSampler;

in vec2 texCoord;
out vec4 fragColor;

void main() {
    float rawDepth = texture(DepthSampler, texCoord).r;
    fragColor = vec4(vec3(rawDepth), 1.0);
}

This displays raw depth, not linearized distance.

---

22. Example: view-distance fog from depth

#version 150

uniform sampler2D InSampler;
uniform sampler2D DepthSampler;

in vec2 texCoord;
out vec4 fragColor;

void main() {
    vec4 color = texture(InSampler, texCoord);

    vec3 viewPos = vpfx_ViewPositionFromRaw(DepthSampler, texCoord);
    float viewDistance = length(viewPos);

    float fogAmount = smoothstep(vpfx_FogStart, vpfx_FogEnd, viewDistance);
    vec3 result = mix(color.rgb, fogColor, fogAmount);

    fragColor = vec4(result, color.a);
}

Graph inputs:

"inputs": [
  {
    "sampler_name": "In",
    "target": "minecraft:scene_color"
  },
  {
    "sampler_name": "Depth",
    "target": "vulkanpostfx:scene_depth"
  }
]

---

23. Example: simple rain-aware color grading

#version 150

uniform sampler2D InSampler;

in vec2 texCoord;
out vec4 fragColor;

void main() {
    vec4 color = texture(InSampler, texCoord);

    vec3 rainyTint = color.rgb * vec3(0.82, 0.88, 1.05);
    vec3 result = mix(color.rgb, rainyTint, vpfx_RainStrength * 0.45);

    fragColor = vec4(result, color.a);
}

This uses:

vpfx_RainStrength

and does not need scene depth.

---

24. Example: day/night tone split

#version 150

uniform sampler2D InSampler;

in vec2 texCoord;
out vec4 fragColor;

void main() {
    vec4 color = texture(InSampler, texCoord);

    vec3 dayGrade = color.rgb * vec3(1.04, 0.99, 0.94);
    vec3 nightGrade = color.rgb * vec3(0.78, 0.86, 1.10);

    vec3 result = vpfx_IsDay ? dayGrade : nightGrade;

    fragColor = vec4(result, color.a);
}

This uses:

vpfx_IsDay

---

25. Example: shadow depth debug view

pack.json should enable shadow depth:

"capabilities": {
  "scene_color": true,
  "scene_depth": false,
  "shadow_depth": true,
  "custom_targets": true,
  "compute": false
},
"targets": {
  "shadow_depth": "vulkanpostfx:shadow_depth"
}

Graph input:

{
  "sampler_name": "Shadow",
  "target": "vulkanpostfx:shadow_depth"
}

Fragment shader:

#version 150

uniform sampler2D ShadowSampler;

in vec2 texCoord;
out vec4 fragColor;

void main() {
    float d = texture(ShadowSampler, texCoord).r;
    fragColor = vec4(vec3(d), 1.0);
}

This displays the shadow map as a texture. It is useful for debugging whether shadow_depth is present, but it is not a final shadow receiver.

---

26. Matrix and coordinate-space notes

26.1 Main scene depth

Scene depth belongs to the main camera.

Use:

vpfx_ViewPositionFromRaw(...)
vpfx_WorldPositionFromRaw(...)

for scene-depth reconstruction.

---

26.2 Shadow depth

Shadow depth belongs to the VPFX shadow pass.

It is not main camera depth.

Current VPFX shadow pass rules:

The shadow map uses shadow-space depth.
The shadow map uses reversed-Z.
The shadow pass is based on the selected light direction.
The shadow pass must not depend on player view direction.
Terrain, entities, players, and block entities may be written into shadow_depth.

Current public uniform limitation:

VpfxBuiltins does not currently expose shadowOrigin.

Therefore, custom pack authors should not yet treat the public uniform set as a complete final shadow receiver API.

---

27. Iris-style aliases currently provided

VPFX currently provides several aliases inspired by common shaderpack naming conventions.

Projection aliases:

gbufferProjection
gbufferProjectionInverse
gbufferPreviousProjection
gbufferPreviousProjectionInverse

View aliases:

gbufferModelView
gbufferModelViewInverse
gbufferPreviousModelView
gbufferPreviousModelViewInverse

Shadow aliases:

shadowModelView
shadowModelViewInverse
shadowProjection
shadowProjectionInverse
shadowViewProjection

Environment aliases:

fogColor
fogStart
fogEnd
skyColor
sunAngle
moonAngle
shadowAngle
sunPosition
moonPosition
shadowLightPosition
upPosition

Important:

These aliases do not mean VPFX is fully compatible with Iris or OptiFine shaderpacks.

They are convenience names for VPFX pack authors.

---

28. What not to assume

Do not assume:

Existing Iris packs can run directly.
shadow_depth is scene_depth.
shadow matrices are player camera matrices.
gbufferModelView contains full world translation.
shadowOrigin is currently exposed in VpfxBuiltins.
compute shaders are available.
all future VPFX versions will keep internal-only uniforms unchanged.

Use only documented public uniforms when writing community packs.

---

29. Current public uniform checklist

You can use these safely in VPFX pack shaders:

vpfx_Time
vpfx_DeltaTime
vpfx_GameTime
vpfx_FrameIndex
vpfx_CameraPos
vpfx_RainStrength
vpfx_ViewSize
vpfx_InvViewSize
vpfx_ZNear
vpfx_ZFar
vpfx_ShadowMapSize
vpfx_ShadowBias
vpfx_FogColor
vpfx_FogStart
vpfx_FogEnd
vpfx_SkyFogEnd
vpfx_CloudFogEnd
vpfx_FogKind
vpfx_SkyColor
vpfx_IsDay
vpfx_SunAngle
vpfx_MoonAngle
vpfx_ShadowAngle
vpfx_SunPosition
vpfx_MoonPosition
vpfx_ShadowLightPosition
vpfx_UpPosition
vpfx_ProjectionMatrix
vpfx_InverseProjectionMatrix
vpfx_PreviousProjectionMatrix
vpfx_PreviousInverseProjectionMatrix
vpfx_ViewRotationMatrix
vpfx_InverseViewRotationMatrix
vpfx_PreviousViewRotationMatrix
vpfx_PreviousInverseViewRotationMatrix
vpfx_ViewProjectionMatrix
vpfx_InverseViewProjectionMatrix
vpfx_ShadowViewMatrix
vpfx_InverseShadowViewMatrix
vpfx_ShadowProjectionMatrix
vpfx_InverseShadowProjectionMatrix
vpfx_ShadowViewProjectionMatrix
vpfx_ViewPositionFromRaw(...)
vpfx_WorldPositionFromRaw(...)

---

30. Recommended first uses

For new pack authors, start with:

vpfx_Time
vpfx_ViewSize
vpfx_InvViewSize
vpfx_RainStrength
vpfx_IsDay
vpfx_SkyColor
vpfx_FogColor

Then move to:

scene depth
projection matrices
view-position reconstruction
world-position reconstruction

Only after that, study:

shadow_depth
shadow matrices
custom shadow receivers

---

31. Next document

This document covers built-in uniforms and helper functions.

The next document should be:

06 - VPFX shadow_depth Guide

That document should explain:

What shadow_depth contains
How reversed-Z shadow depth works
What can and cannot be done with current public uniforms
Why shadowOrigin matters
How to debug shadow_depth
How to avoid treating shadow_depth as scene_depth
Future shadow receiver API requirements