Spatial shaders

Spatial shaders are used for shading 3D objects. They are the most complex type of shader Godot offers. Spatial shaders are highly configurable with different render modes and different rendering options (e.g. Subsurface Scattering, Transmission, Ambient Occlusion, Rim lighting etc). Users can optionally write vertex, fragment, and light processor functions to affect how objects are drawn.

Render modes

Render mode

Description

blend_mix

Mix blend mode (alpha is transparency), default.

blend_add

Additive blend mode.

blend_sub

Subtractive blend mode.

blend_mul

Multiplicative blend mode.

depth_draw_opaque

Only draw depth for opaque geometry (not transparent).

depth_draw_always

Always draw depth (opaque and transparent).

depth_draw_never

Never draw depth.

depth_draw_alpha_prepass

Do opaque depth pre-pass for transparent geometry.

depth_test_disable

Disable depth testing.

cull_front

Cull front-faces.

cull_back

Cull back-faces (default).

cull_disabled

Culling disabled (double sided).

unshaded

Result is just albedo. No lighting/shading happens in material.

diffuse_lambert

Lambert shading for diffuse (default).

diffuse_lambert_wrap

Lambert wrapping (roughness dependent) for diffuse.

diffuse_oren_nayar

Oren Nayar for diffuse.

diffuse_burley

Burley (Disney PBS) for diffuse.

diffuse_toon

Toon shading for diffuse.

specular_schlick_ggx

Schlick-GGX for specular (default).

specular_blinn

Blinn for specular (compatibility).

specular_phong

Phong for specular (compatibility).

specular_toon

Toon for specular.

specular_disabled

Disable specular.

skip_vertex_transform

VERTEX/NORMAL/etc. need to be transformed manually in vertex function.

world_vertex_coords

VERTEX/NORMAL/etc. are modified in world coordinates instead of local.

ensure_correct_normals

Use when non-uniform scale is applied to mesh.

vertex_lighting

Use vertex-based lighting.

shadows_disabled

Disable computing shadows in shader.

ambient_light_disabled

Disable contribution from ambient light and radiance map.

shadow_to_opacity

Lighting modifies the alpha so shadowed areas are opaque and non-shadowed areas are transparent. Useful for overlaying shadows onto a camera feed in AR.

Built-ins

Values marked as "in" are read-only. Values marked as "out" are for optional writing and will not necessarily contain sensible values. Values marked as "inout" provide a sensible default value, and can optionally be written to. Samplers are not subjects of writing and they are not marked.

Global built-ins

Global built-ins are available everywhere, including custom functions.

Built-in

Description

in float TIME

Global time, in seconds.

in float PI

A PI constant (3.141592). A ration of circle's circumference to its diameter and amount of radians in half turn.

in float TAU

A TAU constant (6.283185). An equivalent of PI * 2 and amount of radians in full turn.

in float E

A E constant (2.718281). Euler's number and a base of natural logarithm.

Vertex built-ins

Vertex data (VERTEX, NORMAL, TANGENT, BITANGENT) are presented in local model space. If not written to, these values will not be modified and be passed through as they came.

They can optionally be presented in world space by using the world_vertex_coords render mode.

Users can disable the built-in modelview transform (projection will still happen later) and do it manually with the following code:

shader_type spatial;
render_mode skip_vertex_transform;

void vertex() {
    VERTEX = (MODELVIEW_MATRIX * vec4(VERTEX, 1.0)).xyz;
    NORMAL = normalize((MODELVIEW_MATRIX * vec4(NORMAL, 0.0)).xyz);
    // same as above for binormal and tangent, if normal mapping is used
}

Other built-ins, such as UV, UV2 and COLOR, are also passed through to the fragment function if not modified.

Users can override the modelview and projection transforms using the POSITION built-in. When POSITION is used, the value from VERTEX is ignored and projection does not happen. However, the value passed to the fragment shader still comes from VERTEX.

For instancing, the INSTANCE_CUSTOM variable contains the instance custom data. When using particles, this information is usually:

  • x: Rotation angle in radians.

  • y: Phase during lifetime (0 to 1).

  • z: Animation frame.

This allows you to easily adjust the shader to a particle system using default particles material. When writing a custom particle shader, this value can be used as desired.

Built-in

Description

in vec2 VIEWPORT_SIZE

Size of viewport (in pixels).

in mat4 INV_CAMERA_MATRIX

World space to view space transform.

in mat4 CAMERA_MATRIX

View space to world space transform.

in mat4 INV_PROJECTION_MATRIX

Clip space to view space transform.

in bool OUTPUT_IS_SRGB

true when calculations happen in sRGB color space (true in GLES2, false in GLES3).

in int INSTANCE_ID

Instance ID for instancing.

in vec4 INSTANCE_CUSTOM

Instance custom data (for particles, mostly).

inout vec3 VERTEX

Vertex in local coordinates.

inout vec3 NORMAL

Normal in local coordinates.

inout vec3 TANGENT

Tangent in local coordinates.

inout vec3 BINORMAL

Binormal in local coordinates.

out vec4 POSITION

If written to, overrides final vertex position.

inout vec2 UV

UV main channel.

inout vec2 UV2

UV secondary channel.

inout vec4 COLOR

Color from vertices.

out float ROUGHNESS

Roughness for vertex lighting.

inout float POINT_SIZE

Point size for point rendering.

inout mat4 MODELVIEW_MATRIX

Model space to view space transform (use if possible).

inout mat3 MODELVIEW_NORMAL_MATRIX

inout mat4 WORLD_MATRIX

Model space to world space transform.

inout mat3 WORLD_NORMAL_MATRIX

inout mat4 PROJECTION_MATRIX

View space to clip space transform.

inout uvec4 BONE_INDICES

inout vec4 BONE_WEIGHTS

out vec4 CUSTOM0

out vec4 CUSTOM1

out vec4 CUSTOM2

out vec4 CUSTOM3

Fragment built-ins

The default use of a Godot fragment processor function is to set up the material properties of your object and to let the built-in renderer handle the final shading. However, you are not required to use all these properties, and if you don't write to them, Godot will optimize away the corresponding functionality.

Built-in

Description

in vec2 VIEWPORT_SIZE

Size of viewport (in pixels).

in vec4 FRAGCOORD

Coordinate of pixel center in screen space. xy specifies position in window, z specifies fragment depth if DEPTH is not used. Origin is lower-left.

in bool FRONT_FACING

true if current face if front face.

in vec3 VIEW

Vector from camera to fragment position (in view space).

in vec2 UV

UV that comes from vertex function.

in vec2 UV2

UV2 that comes from vertex function.

in vec4 COLOR

COLOR that comes from vertex function.

in vec2 POINT_COORD

Point Coordinate for drawing points with POINT_SIZE.

in bool OUTPUT_IS_SRGB

true when calculations happen in sRGB color space (true in GLES2, false in GLES3).

in mat4 WORLD_MATRIX

Model space to world space transform.

in mat3 WORLD_NORMAL_MATRIX

in mat4 INV_CAMERA_MATRIX

World space to view space transform.

in mat4 CAMERA_MATRIX

View space to world space transform.

in mat4 PROJECTION_MATRIX

View space to clip space transform.

in mat4 INV_PROJECTION_MATRIX

Clip space to view space transform.

in vec3 VERTEX

Vertex that comes from vertex function (default, in view space).

sampler2D SCREEN_TEXTURE

Built-in Texture for reading from the screen. Mipmaps contain increasingly blurred copies.

in vec2 SCREEN_UV

Screen UV coordinate for current pixel.

sampler2D NORMAL_ROUGHNESS_TEXTURE

sampler2D DEPTH_TEXTURE

Built-in Texture for reading depth from the screen. Must convert to linear using INV_PROJECTION.

out float DEPTH

Custom depth value (0..1).

inout vec3 NORMAL

Normal that comes from vertex function (default, in view space).

inout vec3 TANGENT

Tangent that comes from vertex function.

inout vec3 BINORMAL

Binormal that comes from vertex function.

out vec3 NORMAL_MAP

Set normal here if reading normal from a texture instead of NORMAL.

out float NORMAL_MAP_DEPTH

Depth from variable above. Defaults to 1.0.

out vec3 ALBEDO

Albedo (default white).

out float ALPHA

Alpha (0..1); if written to, the material will go to the transparent pipeline.

out float ALPHA_SCISSOR_THRESHOLD

If written to, values below a certain amount of alpha are discarded.

out float ALPHA_HASH_SCALE

out float ALPHA_ANTIALIASING_EDGE

out vec2 ALPHA_TEXTURE_COORDINATE

out float METALLIC

Metallic (0..1).

out float SPECULAR

Specular. Defaults to 0.5, best not to modify unless you want to change IOR.

out float ROUGHNESS

Roughness (0..1).

out float RIM

Rim (0..1). If used, Godot calculates rim lighting.

out float RIM_TINT

Rim Tint, goes from 0 (white) to 1 (albedo). If used, Godot calculates rim lighting.

out float CLEARCOAT

Small added specular blob. If used, Godot calculates Clearcoat.

out float CLEARCOAT_GLOSS

Gloss of Clearcoat. If used, Godot calculates Clearcoat.

out float ANISOTROPY

For distorting the specular blob according to tangent space.

out vec2 ANISOTROPY_FLOW

Distortion direction, use with flowmaps.

out float SSS_STRENGTH

Strength of Subsurface Scattering. If used, Subsurface Scattering will be applied to object.

out vec4 SSS_TRANSMITTANCE_COLOR

out float SSS_TRANSMITTANCE_DEPTH

out float SSS_TRANSMITTANCE_CURVE

out float SSS_TRANSMITTANCE_BOOST

inout vec3 BACKLIGHT

out float AO

Strength of Ambient Occlusion. For use with pre-baked AO.

out float AO_LIGHT_AFFECT

How much AO affects lights (0..1; default 0).

out vec3 EMISSION

Emission color (can go over 1,1,1 for HDR).

out vec4 FOG

If written to, blends final pixel color with FOG.rgb based on FOG.a.

out vec4 RADIANCE

If written to, blends environment map radiance with RADIANCE.rgb based on RADIANCE.a.

out vec4 IRRADIANCE

If written to, blends environment map IRRADIANCE with IRRADIANCE.rgb based on IRRADIANCE.a.

Light built-ins

Writing light processor functions is completely optional. You can skip the light function by setting render_mode to unshaded. If no light function is written, Godot will use the material properties written to in the fragment function to calculate the lighting for you (subject to the render_mode).

To write a light function, assign something to DIFFUSE_LIGHT or SPECULAR_LIGHT. Assigning nothing means no light is processed.

The light function is called for every light in every pixel. It is called within a loop for each light type.

Below is an example of a custom light function using a Lambertian lighting model:

void light() {
    DIFFUSE_LIGHT += clamp(dot(NORMAL, LIGHT), 0.0, 1.0) * ATTENUATION * ALBEDO;
}

If you want the lights to add together, add the light contribution to DIFFUSE_LIGHT using +=, rather than overwriting it.

Warning

The light() function won't be run if the vertex_lighting render mode is enabled, or if Rendering > Quality > Shading > Force Vertex Shading is enabled in the Project Settings. (It's enabled by default on mobile platforms.)

Built-in

Description

in vec2 VIEWPORT_SIZE

Size of viewport (in pixels).

in vec4 FRAGCOORD

Coordinate of pixel center in screen space. xy specifies position in window, z specifies fragment depth if DEPTH is not used. Origin is lower-left.

in mat4 WORLD_MATRIX

Model space to world space transform.

in mat4 CAMERA_MATRIX

View space to world space transform.

in mat4 INV_CAMERA_MATRIX

World space to view space transform.

in mat4 PROJECTION_MATRIX

View space to clip space transform.

in mat4 INV_PROJECTION_MATRIX

Clip space to view space transform.

in vec3 NORMAL

Normal vector, in view space.

in vec2 UV

UV that comes from vertex function.

in vec2 UV2

UV2 that comes from vertex function.

in vec3 VIEW

View vector, in view space.

in vec3 LIGHT

Light Vector, in view space.

in vec3 LIGHT_COLOR

Color of light multiplied by energy.

in float ATTENUATION

Attenuation based on distance or shadow.

in vec3 SHADOW_ATTENUATION

in vec3 ALBEDO

Base albedo.

in vec3 BACKLIGHT

in float METALLIC

Metallic.

in float ROUGHNESS

Roughness.

in bool OUTPUT_IS_SRGB

true when calculations happen in sRGB color space (true in GLES2, false in GLES3).

out vec3 DIFFUSE_LIGHT

Diffuse light result.

out vec3 SPECULAR_LIGHT

Specular light result.

out float ALPHA

Alpha (0..1); if written to, the material will go to the transparent pipeline.