Special effects in games

Special effects are very important to increase the impression of interaction in the game. On the one hand, a good special effect system can greatly improve the characteristics of the game. This is especially reflected in action games, such as god of war and ninja gaiden. Here is a brief summary of some of the more common special effects in the game you know:

Announcement board

The announcement board effect is to use the announcement board directly to render a certain special effect. The plane direction of a general announcement board is always perpendicular to the line of sight, but you can also add its attribute to avoid being perpendicular to the line of sight. In this case, it is equivalent to drawing a shape at some positions, in this way, some special effects can be completed, such as texture animation on the static surface (this requires the engine to support dynamic textures, such as GIF, or merge and extract frame textures ).

Particle

In particle effects, the most common and necessary effects in the engine, including the implementation of various effects such as dust, flame, smoke, etc., are all completed by the particle system. A particle system is a process model that combines modeling and animation into a whole and uses a single particle that changes over time as the basic element of the scene. Each particle has its own life cycle, such as "birth", "growth", "death" and other basic attributes. In the implementation process, random methods are required to realize the uncertainty of particles, thus increasing more realistic simulation. Each particle is implemented by rendering the announcement board and combining different Alpha operations.

Tail

The drag-and-tail effect is common in action games. The general implementation is to set some corresponding binding points in the model to be rendered, then, the position of these binding points is recorded during the animation playback process, and different types of connection surfaces are generated on them, which are rendered using a variety of Alpha operation models. These generated patches are also updated during the animation update process to achieve dynamic changes. It usually combines certain environmental reflection or distortion to enhance its expressiveness. This special effect is common in a game of action or in a role's motion. A good implementation can greatly increase the engine's expressiveness. For example, the drag-and-drop effect on the weapons in the following Ares is very dazzling.

Sticker

In a strict sense, the effect of a sticker is not completely within the scope of a special effect. For example, it may also be required in the scenario editor because it is not dynamic but part of a static scenario. The current Paster implementation can be implemented in both the traditional method based on forward rendering and the post-processing method. However, this requires the engine to use a delayed rendering architecture, the specific differences are related to the engine details (we have also briefly introduced the implementation ). In the game, the stickers are mainly used on dynamic images or trace surfaces, such as bullet holes in the game, footprints on the snow, and blood stains on the ground caused by attacks, these implementations usually need to be combined with the logic part of the engine to generate a reasonable appearance at a specific time on a specific occasion to enhance the surface force. For example, ninja
Effects of some decal in gaiden (pay attention to the blood stains on the role and on the ground ):

Shadow

Shadow is mainly used to express the rapid movement effect of a role, and its implementation method can be either post-processing or non-post-processing. In general, the implementation method based on geometric entities in the forward direction may achieve better results. In post-processing implementation, we mainly use the accumulation buffer of backups to accumulate the role based on the screen space. The advantage is that the implementation efficiency is high. After all, it is based on the image space, however, there is also an obvious drawback: the effect is not very good, especially when the camera position changes more vigorously, there is also the use of this method, the cumulative effect of poor material controllability, there are not many changes. Another way is to implement model-based rendering based on the forward direction. This is usually to make a virtual copy of the model and then restore and draw the next frame, this method will not be affected by changes in camera, and because it is a direct rendering of ry, the material control is simple, and the effect is better. In addition, this method can also be combined with other special effects. For example, you can use the tail to connect multiple shadows to achieve another more dazzling effect. This effect is available in the latest ninja
Gaiden3 is also widely used, and the effect is also very good (blue motion traces behind the protagonist's rapid attack)

Screen Effects

Screen effects are generally an image-space-based operation that is applied during post-processing to simulate certain effects on the camera, such as screen vertigo in FPS games and screen splash in motion games. The implementation of this operation is actually very simple. You only need to add an Alpha mixture of the target texture in the subsequent process, however, it is important to control the Gradient Based on Alpa, trigger triggered by the combination of logic in the engine, and trigger randomness control in various States, it also requires us to prepare good screen and alpha channel textures for use. For example, in ninja gaiden, after the main character attack, the enemy's bloodstains screen splash effect:

Note:

• Special effects can be managed in the engine in the form of a certain type of node, and it should be equivalent to other nodes. For example, the role model should be equivalent, participate in the corresponding visibility testing, frame update, and other operations.
• Basically, non-post-processing effects and post-processing effects are distributed, which are decomposed from the implementation methods of special effects. There are also some differences between the two implementation methods, however, the corresponding update, load, and release operations are slightly different.
• The editor must be provided in the engine for the artist to use. It can be independent from other editors such as the scenario. However, a unified engine framework (including resource and logic Management) must be used, rendering process.
• Some special effects may need to be bound to a specific model, and the status may be affected by these associated models. Therefore, you must pay attention to these effects when organizing scenarios.
• Because the special effects involve indispensable operations such as alpha mixing, rendering must be completed in the support for translucent pass. For different engine rendering pipelines, the rendering position of the entire special effect part may be different. There is nothing special in the traditional forward rendering engine; In the engine structure using delayed rendering or illumination, You need to place the special effect rendering in a forward rendering stream. Post-processing effects must be placed in a suitable post-processing pass.

The above briefly introduces the implementation of some common special effects in the game. The principle is simple and not complex, but the most important thing is to integrate these effects into the editor, it also provides key property adjustment interfaces for the artist to use and design, in order to get the expected results in the game. Of course, no matter what type of game you want to improve the experience of special effects is a very important part, in addition to the above many, in some cases, you also need to design the corresponding implementation according to the needs of the artist, this requires a detailed analysis of specific issues.