Plugins

While Korender materials offer a robust set of built-in rendering features, advanced use cases may require custom logic beyond the standard parameters. To support this, Korender utilizes Shader Plugins.

Shader Plugins are modular blocks of GLSL code that allow developers to extend the engine's core rendering functionality. These plugins are injected into the pipeline at predefined Extension Points, enabling custom behavior without requiring a full rewrite of the base shaders.

Plugin may introduce their own uniforms to parameterize the material. Also they have access to fragment/vertex properties.

Extension points

Vertex shader extensions

Extension Point	Function signature	Return value
vposition	vec4 pluginVPosition()	Vertex world space position
vnormal	vec3 pluginVNormal()	Vertex world space normal

Global variables available to vertex plugins:

in vec3 pos;        // vertex attribute
in vec3 normal;     // vertex attribute
in vec2 tex;        // vertex attribute
#uniform mat4 model;    // model matrix

Fragment shader extensions

Extension Point	Function signature	Return value
position	vec3 pluginPosition()	Overrides world-space fragment position
texturing	vec4 pluginTexturing()	Multiplier for texture color
normal	vec3 pluginNormal()	Overrides world-space normal
albedo	vec4 pluginAlbedo()	Overrides fragment albedo (unlit color)
discard	bool pluginDiscard()	Overrides fragment discard test
emission	vec3 pluginEmission()	Defines light emission color
metallic_roughness	vec2 pluginMetallicRoughness	Overrides material's metallic and roughness factors
specular_glossiness	vec2 pluginSpecularGlossiness	Switched material model to specular/glossiness and provides the corresponding factors
occlusion	float pluginOcclusion	Overrides occlusion value at fragment

Global variables available to fragment plugins:

in vec3 vpos;       // world position from vertex shader
in vec3 vnormal;    // normal from vertex shader
in vec2 vtex;       // texture coordinates
vec3 position;      // world position (may be modified in the shader)
vec4 albedo;        // fragment albedo (unlit color)
vec3 normal;        // normal (may be modified in the shader)
vec3 emission;      // emission color
float metallic;     // metallic factor
float roughness;    // roughness factor
vec3 look;      // world space vector from camera to fragment

Example:

texturing.wave.frag:

#uniform float wavescale;

vec4 pluginTexturing() {
    float wave = 0.5 + 0.5 * sin(vtex.x * wavescale) * sin(vtex.y * wavescale); 
    return vec4(wave, 0., 0., 1.);
}

Renderable(
  base(),
  plugin("texturing", "shaders/texturing.wave.frag"),
  uniform("wavescale", 10f),
  mesh = ....
...