There are a total of 4 base materials setup for the Blood Hit System. The goal with this system is to keep shader instructions low, reuse the same textures as much as possible to help with memory cost and avoid spawning particles with a lot of translucency. Therefore, the main shaders are Opaque Masked materials and the secondary and tertiary elements are Translucent.
Materials/Material Instances:
Blood Drops - M_BloodDrops_CPU_BASE > MI_BloodDrops_CPU_0X
Blood Hit - M_BloodHit_CPU_BASE > MI_BloodHit_CPU_0X
Blood Hit Mist - M_BloodHitMist_CPU_BASE > MI_BloodHitMist_CPU_0X
Blood Hit Mixed - M_BloodHitMixed_CPU_BASE > MI_BloodHitMixed_CPU_0X
Unreal Materials Location: Content > VFX > Materials > Blood
USING THE MATERIAL INSTANCES
Each blood MI has a set of parameters and texture slots that should be used sparingly. You can view all of them further down the page in the MATERIALS REFERENCE section.
Material Instance Layout
1. Blood Color
For the most part this section can be left on the defaults as these have been fine tuned already, however if they need to be changed they are pretty self-explanatory. The EDGE BLOOD is a faked Subsurface emission that helps give a translucency around the edge of the blood, so adjust that one more incrementally.
2. Parameters/Switches
Channel Switches
Most notably you will see that there are switches related to various channels (i.e. Use Distortion B Chan) . The channels relate to the Blue and Green channels in the T_BloodMist_01_Packed texture. The Instance will use the Red channel by default. This can be useful to save on texture memory if a variation of distortion or erosion should be needed.
Master Blood Color Switch
This switch controls the use of the MPC. By default it uses the MPC hooked up in the material. If turned off, you can manually define the blood colors for the particular instance.
3. Textures
Reuse
To save on texture memory in the particle system it is advantageous to reuse the same texture across Material Instances if possible. For example T_BlodMist_01_Packed can be used on all instances of related materials to one particle system since it has enough versatility in the packed channels. You will see that it is also used in the Blood Drops and additional Blood Hit Materials.
Blood Hits
You may notice that only the Red Channel of the MI_BloodHit_CPU_03 material is being used. The same texture is used in MI_BloodHitMixed_CPU_01 and uses the Green and Blue channels. This also helps save on texture memory.
Normal Maps
There is only one normal used and required and that normal belongs to the actual blood splash. This way there is at least one aspect to the blood that has roughness and reflects light while the translucent shaders help fill out the effect.
MATERIAL PARAMETER COLLECTION
This MPC contains the Blood colors for uniformity across all of the Blood systems. If the Blood Hit Materials need to apply to other characters/NPCs with a different color, then the color can be changed in the Material Instance or if it needs to be widely applied to multiple creatures NPCs then new MPCs and Materials should be constructed.
MPC Location: Content > VFX > MPCs > MPC_BloodHitColor_01
MPC Values
The Universal blood colors are defined here and should only be changed if the global look of the blood needs to change. DO NOT change these values for stylized blood colors. Those should be defined in individual Material Instances or in a NEW MPC that has been applied to new materials.
MPC Material Use
The MPCs are hooked up in the following manner inside of each material. They are connected to switches that are turned ON by default to utilize the global blood values in the MPCs.
MATERIALS REFERENCE
Blood Drops (Opaque Masked Material)
Blood Drops Material Instance
Blood Hit (Opaque Masked Material)
Blood Hit Material Instance
Blood Hit Mist (Translucent Material)
Blood Hit Mist Material Instance
Blood Hit Mixed (Translucent Material)
Blood Hit Mixed Material Instance
For next steps please see BHS - Particle System Overview