Language:
Page Info
Tags:
Engine Version:

Blueprint Debugging

Choose your OS:

Blueprint debugging is a very powerful feature that allows you to pause execution of the game in Play In Editor or Simulate In Editor mode and step through any graph of a Blueprint or Level Blueprint through the use of Breakpoints.

Debugging Controls

The debug controls allow execution of the game in Play In Editor and Simulate In Editor mode to be controlled. The controls become enabled in the Blueprint Editor when the game is running. Different debugging-specific buttons appear on the Toolbar depending on the type of Blueprint being debugged and the current state of the debugging.

debugging_editor.png

Both the Debug tab, which can be opened from the Blueprint Editor's window menu, and the Blueprint Debugger will also display the context-sensitive debugging buttons when Simulate in Editor or Play in Editor modes are active.

The debug controls allow execution of the game in Play In Editor and Simulate In Editor mode to be controlled. The controls become enabled when the game is running. Different debugging-specific buttons appear on the Toolbar depending on the type of Blueprint being debugged and the current state of the debugging. Some controls only become enabled when relevant, i.e. when a Breakpoint is hit.

blueprint_debugger.png

Breakpoints

Breakpoints allow execution of the game to be paused at a certain point when running the game in the editor. All Breakpoints for all graphs belonging to a Blueprint or Level Blueprint are displayed in the Debug tab. The names of the Breakpoints in this list are hyperlinked allowing you to click on them and be taken directly to the node associated with the Breakpoint in the Graph tab.

Breakpoints can be set on any node in the graph that gets executed, such as Function Calls and Flow Control operations, by Right-clicking on the node and choosing Add Breakpoint. When a Breakpoint has been set on a node, a graphic is displayed in the upper-left corner of the node.

Blueprint Debugging - Breakpoint Enabled

Breakpoints can be disabled as well by Right-clicking on the node and choosing Disable Breakpoint or clicking the icon next to the Breakpoint in the Debug to toggle it off. This can also be done by Right-clicking the Breakpoint in the Debug tab and choosing Disable Breakpoint.

Blueprint Debugging - Breakpoint Disable Option

This leaves the Breakpoint in place, but it will not stop the game when the node is executed. A disabled Breakpoint is displayed as just an outline.

Blueprint Debugging - Breakpoint Disabled

To enable a disabled Breakpoint, Right-click on the node and choose Enable Breakpoint or click the icon next to the Breakpoint in the Debug tab. This can also be done by Right-clicking the Breakpoint in the Debug tab and choosing Enable Breakpoint.

Blueprint Debugging - Breakpoint Enable Option

Breakpoints can be removed by Right-clicking the node or Right-clicking the Breakpoint in the Debug tab and choosing Remove Breakpoint.

When a Breakpoint is hit, the graph will focus on the node containing the Breakpoint and an indicator is displayed on the Breakpoint.

Blueprint Debugging - Breakpoint Hit Indicator

In addition, the viewport will display an overlay to alert the player that the game has been paused for debugging.

Blueprint Debugging - Viewport overlay

Debug Tab and Blueprint Debugger

The Debug tab shows information designated as important by the designer in the form of Breakpoints and watch values as well as a trace stack of all nodes belonging to the Blueprint that have been executed. This window also shows controls for controlling execution of the game when using Breakpoints.

Watch Values

Watch values allow you to quickly and easily see the values of variables during execution. All watch values for the selected Actor as well as the Level Blueprint are displayed in the Debug window when debugging after a Breakpoint is hit and update as you step through the graph.

Blueprint Debugging - Watch Values

Values being watched also have the ability to be displayed directly in the graph as a bubble above the variable.

Blueprint Debugging - Watch Value Info Bubble

To enable the display of the watch information bubble, simply click the magnifying glass (Blueprint Debugging - Watch Value Button) next to the variable's name.

Execution Trace

The Execution Trace stack shows a list of the nodes executed with the most recent at the top.

Blueprint Debugging - Execution Trace Stack

This list updates as you step through the graph when debugging.

Tags