Using effects in the Kanzi Engine API

You can use the Kanzi Engine API to create effects for 2D nodes.

Assigning effects to nodes

To create an effect:

// An effect that is assigned to a 2D node is an effect prefab.
// Before you can construct an effect prefab, you must create an effect template.
// This example creates an effect template for the ShadowEffect2D effect prefab.
NodeEffectTemplate2DSharedPtr shadowEffectTemplate =
    NodeEffectTemplate2D::create(ShadowEffect2D::getStaticMetaclass()->getName(), "DropShadow");

// Create a node effect prefab from the effect template.
NodeEffectPrefab2DSharedPtr shadowEffectPrefab =
    NodeEffectPrefab2D::create(getDomain(), "DropShadow prefab", shadowEffectTemplate);

To set a 2D node to use an effect:

// To assign an effect prefab to a 2D node, set the Node2D::EffectPrefabProperty.
node2d->setProperty(Node2D::EffectPrefabProperty, shadowEffectPrefab);

// To assign an effect prefab to a 2D node, call the Node2D::setEffectPrefab method.
node2d->setEffectPrefab(shadowEffectPrefab);

To disable an effect:

// Enable an effect on a 2D node by assigning an effect prefab.
node2d->setEffectPrefab(shadowEffectPrefab);
// Disable an effect by assigning a nullptr or an empty shared pointer.
node2d->setEffectPrefab(nullptr);

To set multiple 2D nodes to use the same effect:

// Create an effect template.
NodeEffectTemplate2DSharedPtr shadowEffectTemplate =
    NodeEffectTemplate2D::create(ShadowEffect2D::getStaticMetaclass()->getName(), "DropShadow");

// Create an effect prefab from the effect template.
NodeEffectPrefab2DSharedPtr shadowEffectPrefab =
    NodeEffectPrefab2D::create(getDomain(), "DropShadow prefab", shadowEffectTemplate);

// Set two nodes to use the same effect prefab. The nodes create separate instances
// of NodeEffect2D but share the same NodeEffectPrefab2D instance.
node1->setEffectPrefab(shadowEffectPrefab);
node2->setEffectPrefab(shadowEffectPrefab);

Creating a blur effect

Use the Blur Effect 2D effect to apply a Gaussian blur to a 2D node.

To create a blur effect for a 2D node using the Kanzi Engine API:

// Create a blur effect template.
NodeEffectTemplate2DSharedPtr blurEffectTemplate =
    NodeEffectTemplate2D::create(BlurEffect2D::getStaticMetaclass()->getName(), "BlurEffect");

// Set the value of the RadiusProperty in the blur effect template.
// RadiusProperty defines the amount of blur.
blurEffectTemplate->addPropertyValue(BlurEffect2D::RadiusProperty, Variant(6.f));

// Create a blur effect prefab.
NodeEffectPrefab2DSharedPtr blurEffectPrefab =
    NodeEffectPrefab2D::create(getDomain(), "BlurEffect prefab", blurEffectTemplate);

// Assign the blur effect to a 2D node.
node2d->setEffectPrefab(blurEffectPrefab);

// Get the node-specific effect instance created from the assigned prefab.
BlurEffect2DSharedPtr blurEffect = dynamic_pointer_cast<BlurEffect2D>(node2d->getEffect());

// Set the MaskedProperty to true. Masked mode maintains the original alpha channel and
// prevents the blur from spreading to fully transparent pixels.
blurEffect->setMasked(true);

For details, see the BlurEffect2D class in the Kanzi Engine API reference.

Creating a mask effect

Use the Mask Effect 2D effect to apply a mask to a 2D node.

To create a mask effect for a 2D node using the Kanzi Engine API:

// Create an effect template.
NodeEffectTemplate2DSharedPtr maskEffectTemplate =
    NodeEffectTemplate2D::create(MaskEffect2D::getStaticMetaclass()->getName(), "MaskEffect");

// Set the value of the MaskProperty in the template.
// The MaskProperty defines the mask texture which you must set before you can use the mask effect.
TextureSharedPtr maskTexture = acquireMaskTexture(getDomain());
maskEffectTemplate->addPropertyValue(MaskEffect2D::MaskProperty, Variant(maskTexture));

// Create a mask effect prefab.
NodeEffectPrefab2DSharedPtr maskEffectPrefab =
    NodeEffectPrefab2D::create(getDomain(), "MaskEffect prefab", maskEffectTemplate);

// Assign the mask effect to a 2D node.
node2d->setEffectPrefab(maskEffectPrefab);

// Get the node-specific effect instance created from the assigned prefab.
MaskEffect2DSharedPtr maskEffect = dynamic_pointer_cast<MaskEffect2D>(node2d->getEffect());

// Set the mask stretch mode to uniform.
maskEffect->setStretch(MaskEffect2D::Stretch::Uniform);

For details, see the MaskEffect2D class in the Kanzi Engine API reference.

Creating a shadow effect

Use the Shadow Effect 2D effect to apply a shadow to the content of a 2D node.

To create a shadow effect for a 2D node using the Kanzi Engine API:

// Create an effect template.
NodeEffectTemplate2DSharedPtr shadowEffectTemplate =
    NodeEffectTemplate2D::create(ShadowEffect2D::getStaticMetaclass()->getName(), "DropShadow");

// Set the value of the AngleProperty in the template. This value serves as the default value
// of the property in instances of the effect prefab.
shadowEffectTemplate->addPropertyValue(ShadowEffect2D::AngleProperty, Variant(35.f));

// Create an effect prefab.
NodeEffectPrefab2DSharedPtr shadowEffectPrefab =
    NodeEffectPrefab2D::create(getDomain(), "DropShadow prefab", shadowEffectTemplate);

// Assign the effect to a 2D node.
node2d->setEffectPrefab(shadowEffectPrefab);

// Get the node-specific effect instance created from the assigned prefab.
ShadowEffect2DSharedPtr shadowEffect = dynamic_pointer_cast<ShadowEffect2D>(node2d->getEffect());

// Set the shadow distance to 15 pixels for this node only. This overrides
// the property default value defined by the ShadowEffect2D metaclass.
shadowEffect->setDistance(15.f);

// Set the direction of the shadow to 55 degrees relative to the positive x axis.
// This overrides the default value of 35 degrees set in the shadow effect template.
shadowEffect->setAngle(55.f);

For details, see the ShadowEffect2D class in the Kanzi Engine API reference.

Creating a custom effect

You can use the Kanzi Engine API to create your own effects for 2D nodes.

To create a custom effect for a 2D node using the Kanzi Engine API:

// To create an effect resource type, inherit a new class from NodeEffect2D
// and define a new associated metaclass. Each effect resource class must
// have an associated renderer class inherited from NodeEffectRenderer2D.

class EmptyEffectRenderer2D;
using EmptyEffectRenderer2DUniquePtr = unique_ptr<EmptyEffectRenderer2D>;

class EmptyEffect2D;
using EmptyEffect2DSharedPtr = shared_ptr<EmptyEffect2D>;

// EmptyEffect2D defines a new effect that defines no properties
// nor padding.
class EmptyEffect2D : public NodeEffect2D
{
public:
    KZ_METACLASS_BEGIN(EmptyEffect2D, NodeEffect2D, "Kanzi.EmptyEffect2D")
    KZ_METACLASS_END()

    // Create an instance of EmptyEffect2D.
    static EmptyEffect2DSharedPtr create(Domain* domain, string_view name)
    {
        return make_polymorphic_shared_ptr<Resource>(new EmptyEffect2D(domain, name));
    }
protected:

    // Constructor.
    explicit EmptyEffect2D(Domain* domain, string_view name) :
        NodeEffect2D(domain, name)
    {
    }

    // NodeEffect2D::createRendererOverride implementation.
    NodeEffectRenderer2DUniquePtr createRendererOverride() override;

    // NodeEffect2D::initializeRendererOverride implementation.
    void initializeRendererOverride() override
    {
    }
};

// EmptyEffectRenderer2D implements the rendering of the effect.
// Because this example effect does not render anything, Kanzi renders
// the original node as is.
class EmptyEffectRenderer2D : public NodeEffectRenderer2D
{
public:
    // Creates an instance of MinimalEffectRenderer2D. Never call this
    // function directly. Instead, use NodeEffect2D::createRenderer().
    static EmptyEffectRenderer2DUniquePtr create(EmptyEffect2DSharedPtr effect)
    {
        return unique_ptr<EmptyEffectRenderer2D>(new EmptyEffectRenderer2D(effect));
    }

private:
    // Constructor.
    explicit EmptyEffectRenderer2D(EmptyEffect2DSharedPtr effect) :
        NodeEffectRenderer2D(effect)
    {
    }

    // Implementation of NodeEffectRenderer2D::beginEffectOverride.
    void beginEffectOverride(Renderer3D& /*renderer*/, CompositionStack& /*compositionStack*/, CompositionManager* /*compositionManager*/,
        const Matrix3x3& /*worldTransform*/, Vector2 /*requiredSize*/, bool /*alphaRequired*/, bool /*depthRequired*/, bool /*stencilRequired*/) override
    {
    }

    // Implementation of NodeEffectRenderer2D::endEffectOverride.
    void endEffectOverride(Renderer3D& /*renderer*/, CompositionStack& /*compositionStack*/, CompositionManager* /*compositionManager*/) override
    {
    }

    // Implementation of NodeEffectRenderer2D::blitEffectOverride.
    void blitEffectOverride(Renderer3D& /*renderer*/, CompositionStack& /*compositionStack*/, CompositionManager* /*compositionManager*/,
        QuadDescription& /*effectQuad*/, const Matrix3x3& /*transform*/, const Matrix4x4* /*perspectiveMatrix*/,
        const Matrix4x4* /*projectionMatrix*/, int /*blendMode*/, bool /*needsClear*/) override
    {
    }

    // Implementation of NodeEffectRenderer2D::restoreResourcesOverride.
    virtual void restoreResourcesOverride() override
    {
    }
};

NodeEffectRenderer2DUniquePtr EmptyEffect2D::createRendererOverride()
{
    return EmptyEffectRenderer2D::create(static_pointer_cast<EmptyEffect2D>(shared_from_this()));
}

For details, see the NodeEffect2D class in the Kanzi Engine API reference.

See also

Effects for 2D nodes

Using the Blur Effect 2D effect

Using the Mask Effect 2D effect

Using the Shadow Effect 2D effect