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 Descrição
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.

Vertex 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.

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 = (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 particles shader, this value can be used as desired.

Built-in Descrição
in float TIME Elapsed total time in seconds.
in vec2 VIEWPORT_SIZE Size of viewport (in pixels).
inout mat4 WORLD_MATRIX Model space to world space transform.
in mat4 INV_CAMERA_MATRIX World space to view space transform.
inout mat4 PROJECTION_MATRIX View space to clip space transform.
in mat4 CAMERA_MATRIX View space to world space transform.
inout mat4 MODELVIEW_MATRIX Model space to view space transform (use if possible).
inout mat4 INV_PROJECTION_MATRIX Clip space to view space transform.
inout vec3 VERTEX Vertex in local coordinates.
out vec4 POSITION If written to, overrides final vertex position.
inout vec3 NORMAL Normal in local coordinates.
inout vec3 TANGENT Tangent in local coordinates.
inout vec3 BINORMAL Binormal in local coordinates.
out float ROUGHNESS Roughness for vertex lighting.
inout vec2 UV UV main channel.
inout vec2 UV2 UV secondary channel.
in bool OUTPUT_IS_SRGB true when calculations happen in sRGB color space (true in GLES2, false in GLES3).
inout vec4 COLOR Color from vertices.
inout float POINT_SIZE Point size for point rendering.
in int INSTANCE_ID Instance ID for instancing.
in vec4 INSTANCE_CUSTOM Instance custom data (for particles, mostly).

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 Descrição
in float TIME Elapsed total time in seconds.
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 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).
in vec3 VIEW Vector from camera to fragment position (in view space).
in bool FRONT_FACING true if current face is front face.
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 NORMALMAP Set normal here if reading normal from a texture instead of NORMAL.
out float NORMALMAP_DEPTH Depth from variable above. Defaults to 1.0.
in vec2 UV UV that comes from vertex function.
in vec2 UV2 UV2 that comes from vertex function.
in bool OUTPUT_IS_SRGB true when calculations happen in sRGB color space (true in GLES2, false in GLES3).
in vec4 COLOR COLOR that comes from vertex function.
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 If written to, values below a certain amount of alpha are discarded.
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 vec3 TRANSMISSION Transmission mask (default 0,0,0). Allows light to pass through object. Only applied if used.
out vec3 EMISSION Emission color (can go over 1,1,1 for HDR).
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).
sampler2D SCREEN_TEXTURE Built-in Texture for reading from the screen. Mipmaps contain increasingly blurred copies.
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).
in vec2 SCREEN_UV Screen UV coordinate for current pixel.
in vec2 POINT_COORD Point Coordinate for drawing points with POINT_SIZE.

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 += dot(NORMAL, LIGHT) * ATTENUATION * ALBEDO;
}

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

Built-in Descrição
in float TIME Elapsed total time in seconds.
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 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 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 ATTENUATION Attenuation based on distance or shadow.
in bool OUTPUT_IS_SRGB true when calculations happen in sRGB color space (true in GLES2, false in GLES3).
in vec3 ALBEDO Base albedo.
in vec3 LIGHT_COLOR Color of light multiplied by energy.
out float ALPHA Alpha (0..1); if written to, the material will go to the transparent pipeline.
in float ROUGHNESS Roughness.
in vec3 TRANSMISSION Transmission mask from fragment function.
out vec3 DIFFUSE_LIGHT Diffuse light result.
out vec3 SPECULAR_LIGHT Specular light result.