Blueprints

• This is based on Blueprints - Essential Concepts
• There are a number of different types of blueprints.
  • Level Blueprints
    • Special behavior for a level.
    • These functions are specific to the level which contains them.
    • Tied to a level.
    • Any data stored in these blueprints goes away when the level is unloaded.
    • No components, just code for a level.
  • Class Blueprints
    • The transporter we built before.
  • Animation blueprints.
    • Used to control animation of a character.
    • I have not messed with these.
    • It has an animation graph that controls what animation is playing.
  • Unreal Motion Graphics ( UI)
    • We will do an entire section on this.
• Blueprints are tightly tied to c++
  • Later when we produce c++ code, it will directly map to a blueprint.
  • Blueprints CAN be compiled to c++ code if you wish.
  • The entire system is hierarchical
    • Base classes are usually c++
    • Later we can derive blueprint classes from base classes.
• Since we are coming from C++, it makes sense that we have a constructor.
  • This is the Construction Script
  • Fires when
    • Changes are made to the blueprint.
    • When instances of the class are created.
• When building an actor blueprint
  • The white sphere is the "Default Scene Root".
    • This is centered at (0,0,0)
    • Selecting this will move the entire thing in the blueprint editor.
  • By dragging, you can nest components
  • And even make something else the scene root.
  • Searching in the event graph is context sensitive based on what is selected.
  • He reviews variables
    • Making them publicly editable
• Collapsing a node to a function.
  • Select the nodes and tell it to collapse to a function.
  • Rename it.
  • You can add input and output parameters as well.
  • Think class member function.
  • Access Specific is public, protected or private
  • Pure means const, vs unpure means will not modify the state of the object.
    • This seems akin to const in c++
    • But I don't think that it is enforced.
  • You can mark variables as pass by reference.
• you can group these into a macro
• You can collapse to a single node.
• Child blueprints
  • Derived class from the parent class.
• Notes on using blueprints.
  • You could do everything in blueprints.
  • But they are not as efficient as c++
    • Complex math, or many operations on every tick = c++
  • Some elements of C++ are not exposed to blueprint.
  • Blueprints must be triggered by an event.
  • Blueprint use References
    • This is a just a parameter/variable error.
  • He discusses casting, but you should know this.
  • You can easily build circular dependencies.
    • Two blueprints that refer to each other.
    • This will possibly cause problems on loading.