Training Stream - Blueprint Drawing to Render Targets Overview - Sept 20 - Live from Epic HQ


Sam Dieter is on to talk about a powerful new feature from the 4.13 release, Blueprint Drawing to Render Targets! There are limitless applications to such a versatile tool, so Sam will give a basic overview and explain how it can be used for general purposes. Also, be sure to check out the BlueprintRenderToTarget map in the ContentExamples project for more working examples!

Tuesday, September 20th @ 2:00PM Countdown]


Sam Deiter - Training Content Creator @Sam_Deiter](
Alexander Paschall - Community Manager @UnrealAlexander](

Feel free to ask any questions on the topic in the thread below, and remember, while we try to give attention to all inquiries, it’s not always possible to answer everyone’s questions as they come up. This is especially true for off-topic requests, as it’s rather likely that we don’t have the appropriate person around to answer. Thanks for understanding!


YES! this is the stream I have been waiting for!

Can also do cool stuff like this pretty easily!

(I really like 4.13)

  1. Can this also to alter the collision and/or navigation of the surface? *(via displacing the surface creating tall mountains and deep ravines, but with collision) *
    If so, how would this impact performance?

  2. Could it be used to permanently affect the terrain of a map (scar the surface), without need to “garbage collect” the scars, creators, and mountains?
    (Example: typical method used Decals to create creators from explosions or impacts, then are later erased to save memory. Could Drawing to Render Targets be used instead, to allow the cumulative creator count to build up throughout the match without the need to erase them to save memory)?

  3. In the content example, the surface normal which you paint on remains flat, even as the ground becomes mountainous you still have to aim down at the floor surface to continue painting.
    Can users alter this behavior so the player has to aim at the “visual raised surface” instead of the ground that it sits on?

  4. Mountainous surfaces get clipped out of the scene if the ground surface is out of view. (Example: The mountain you painted disappears if you look “up” too far, because the ground is no longer in view)
    Can users alter this behavior so the raised surfaces remain in view even when the ground is not seen?

I have been waiting for this for 2 years!
One questions though: how can we create render target in a blueprint with certain format? E.g. I need only 1 channel to render height field.

Here’s what I’ve done btw :slight_smile:

In C++, the documentation says to call FindCanvasRenderTarget2D() or create a new one.
Unfortunately the mentioned function doesn’t exist.

Nice! That’s awesome. If I don’t learn how to do that after watching their stream I’d like you to help me out. I want to make a whiteboard now!

Wow! That’s amazing… The table and bench are well done and worth a purchase on the marketplace. J/K. Love the effects!


Cool! Would it by any chance be possible to do a breakdown of the examples? Like, briefly explain what does what? It would help me to better understand the examples, and the math involved.

IS it possible to use this technique to render liquid inside an object like a glass bottle? I’m looking for a solution that can give the illusion of gravity acting on liquid in a half filled glass bottle.

Is there a way to directly convert overlap collision to texture? - Specific scenario: An energy shield that registers overlaps with bullets, but lets them through. The Bullets should then cause wave-like ripples in the energy shield.

  • It would be even more impressive if the initial shape of the ripple has the exact shape of the projectile.

@devast3d- How?! Awesome work!

Same Question as this guy, but a different example scenario:

Can this be used to add ripples to characters skin?

  • (like when a boxer punches another boxer in the gut, and the shockwave ripples through their body?)*

It works like this:

  • Main simulator actor blueprint simulates array of droplets (which are just blueprints based on UObject)
  • Then I’m using render to texture for each droplet (basically just drawing the quad in certain place with certain rotation, i.e. like drawing particles), producing heightfield as the result
  • Convert heightfield to normal map, assemble all the data and write to the final render target which is fed to special post processing material which draws droplets on the screen (I’ve had static droplets for a long time, but now I can create animated at runtime).

Although the “simulation” is not physically based, it’s clever moved and rendered quads with no physics at all :slight_smile:

Excited to see this in detail!

Question: Is it possible to make a material change (say change colour) based on the position of another actor in the scene? For example making a wall turn red as another actor moves across it as if painting the surface. It looks possible from the whiteboard example.

Awesome was waiting it !!
is Daniel or Ryan going to be there that would be awesome to see some of there (black) MAGIC ?? JK

Step aside Photoshop. Now all we need is a proper brush engine and we’ll be free from adobellend

I am not going to be on this time but perhaps sometime soon. In the mean time I have uploaded a blog post talking about methods for dilating UV layouts to use with mesh painting. I will be posting another one soon showing how to use parallax occlusion mapping on curved surfaces by using the render target tool to bake out transform maps.

That’s freaking incredible!!!

You should do a blog post on your volumetrics/raymarching if you have the time :smiley:

Is there a way of rendering rectangles to the render target, so you don’t have to redraw the whole render target every time you update it with a material?