Archive 17/01/2023.

Per instance shader parameters?

throwawayerino

My shader takes in a boolean and whenever I toggle the parameter using SetShaderParameter() all models with the same material also get changed. I could easily clone the material, but 1) I would lose instancing optimization and 2) isn’t easy to do in the editor

Eugene

There is a hack that let you pass additional per-instance data.
However, it can be done only if you make new drawable component and manually fill or edit batches (maybe inherited from existing one).

github.com

urho3d/Urho3D/blob/master/Source/Urho3D/Graphics/Drawable.h#L104


    float distance_{};

    /// Geometry.

    Geometry* geometry_{};

    /// Material.

    SharedPtr<Material> material_;

    /// World transform(s). For a skinned model, these are the bone transforms.

    const Matrix3x4* worldTransform_{&Matrix3x4::IDENTITY};

    /// Number of world transforms.

    unsigned numWorldTransforms_{1};

    /// Per-instance data. If not null, must contain enough data to fill instancing buffer.

    void* instancingData_{};

    /// %Geometry type.

    GeometryType geometryType_{GEOM_STATIC};

};



/// Base class for visible components.

class URHO3D_API Drawable : public Component

{

    URHO3D_OBJECT(Drawable, Component);



    friend class Octant;

github.com

urho3d/Urho3D/blob/master/Source/Urho3D/Graphics/Renderer.h#L230


void SetVSMMultiSample(int multiSample);

/// Set post processing filter to the shadow map.

void SetShadowMapFilter(Object* instance, ShadowMapFilter functionPtr);

/// Set reuse of shadow maps. Default is true. If disabled, also transparent geometry can be shadowed.

void SetReuseShadowMaps(bool enable);

/// Set maximum number of shadow maps created for one resolution. Only has effect if reuse of shadow maps is disabled.

void SetMaxShadowMaps(int shadowMaps);

/// Set dynamic instancing on/off. When on (default), drawables using the same static-type geometry and material will be automatically combined to an instanced draw call.

void SetDynamicInstancing(bool enable);

/// Set number of extra instancing buffer elements. Default is 0. Extra 4-vectors are available through TEXCOORD7 and further.

void SetNumExtraInstancingBufferElements(int elements);

/// Set minimum number of instances required in a batch group to render as instanced.

void SetMinInstances(int instances);

/// Set maximum number of sorted instances per batch group. If exceeded, instances are rendered unsorted.

void SetMaxSortedInstances(int instances);

/// Set maximum number of occluder triangles.

void SetMaxOccluderTriangles(int triangles);

/// Set occluder buffer width.

void SetOcclusionBufferSize(int size);

/// Set required screen size (1.0 = full screen) for occluders.

void SetOccluderSizeThreshold(float screenSize);