material

type GPUEffectParams struct {
	TintColor [4]float32 // offset 0: RGB tint color + alpha blend intensity (16 bytes)
}

type GPUOverlayParams struct {
	OverlayColor [4]float32 // offset 0: RGBA overlay color written to all fragments (16 bytes)
}

type Material interface {
	common.Delegate[Material]

	// Name retrieves the material identifier.
	//
	// Returns:
	//   - string: the name of the material
	Name() string

	// BaseColor retrieves the albedo/diffuse RGBA color of the material.
	//
	// Returns:
	//   - [4]float32: the base color as RGBA values
	BaseColor() [4]float32

	// Metallic retrieves the metallic factor of the material.
	// A value of 0.0 represents a dielectric surface, 1.0 represents a fully metallic surface.
	//
	// Returns:
	//   - float32: the metallic factor
	Metallic() float32

	// Roughness retrieves the roughness factor of the material.
	// A value of 0.0 represents a perfectly smooth surface, 1.0 represents a fully rough surface.
	//
	// Returns:
	//   - float32: the roughness factor
	Roughness() float32

	// DiffuseTexture retrieves the diffuse/albedo texture data reference, or nil if none is set.
	//
	// Returns:
	//   - *common.ImportedTexture: the diffuse texture, or nil
	DiffuseTexture() *common.ImportedTexture

	// NormalTexture retrieves the normal map texture data reference, or nil if none is set.
	//
	// Returns:
	//   - *common.ImportedTexture: the normal texture, or nil
	NormalTexture() *common.ImportedTexture

	// MetallicRoughnessTexture retrieves the metallic-roughness texture data reference, or nil if none is set.
	//
	// Returns:
	//   - *common.ImportedTexture: the metallic-roughness texture, or nil
	MetallicRoughnessTexture() *common.ImportedTexture

	// PipelineKey retrieves the key identifying the render pipeline this material uses.
	//
	// Returns:
	//   - string: the pipeline key
	PipelineKey() string

	// BindGroupProvider retrieves the bind group provider holding GPU-side resources for this material.
	//
	// Returns:
	//   - bind_group_provider.BindGroupProvider: the bind group provider, or nil if not yet initialized
	BindGroupProvider() bind_group_provider.BindGroupProvider

	// SetPipelineKey sets the render pipeline key for this material.
	//
	// Parameters:
	//   - key: the pipeline key to associate with this material
	SetPipelineKey(key string)

	// SetBindGroupProvider sets the bind group provider for this material.
	//
	// Parameters:
	//   - provider: the bind group provider containing GPU resources for this material
	SetBindGroupProvider(provider bind_group_provider.BindGroupProvider)

	// FragmentShaderPath retrieves the path to the fragment shader associated with this material.
	// An empty string indicates that the engine default fragment shader should be used.
	//
	// Returns:
	//   - string: the fragment shader asset path, or empty for the engine default
	FragmentShaderPath() string

	// SetFragmentShaderPath sets the path to the fragment shader for this material.
	//
	// Parameters:
	//   - path: the fragment shader asset path
	SetFragmentShaderPath(path string)

	// Provider retrieves the bind group provider associated with the specified group index.
	// Returns nil if no provider has been set for the given group.
	//
	// Parameters:
	//   - group: the bind group index to look up
	//
	// Returns:
	//   - bind_group_provider.BindGroupProvider: the provider for the group, or nil
	Provider(group int) bind_group_provider.BindGroupProvider

	// SetProvider stores a bind group provider for the specified group index.
	// This allows a material to own GPU resources across multiple bind groups
	// (e.g. textures at one group and effect uniforms at another).
	//
	// Parameters:
	//   - group: the bind group index
	//   - provider: the bind group provider to associate with the group
	SetProvider(group int, provider bind_group_provider.BindGroupProvider)
}

type MaterialBuilderOption func(*material)