#Shadow casting different shadow lengths for different objects

41 messages · Page 1 of 1 (latest)

real grove
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Hello. I am playing around with a 2D Top Down game and I would like to cast different length shadows. For example the player should cast a smaller shadow than a wall. I tried to in paint to illustrate what I mean

In the image I have two types of walls. A tall wall and a half wall. What I would like to do is to give the illusion of that the half wall is indeed a half wall and to do that I would like to cast a shorter shadow than the tall wall.

I am not sure how to approach this problem.

image.png
trim rune
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You don't understand what you want. So nobody understands what you want. And that's the reason you can't find a solution. Because the goal is undefined

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Wtf is that drawn red line

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So... Figure out what you're trying to achieve and ask once again. Because the shadow length is a setting in Light component as well as "Quality" tab in project settings. And I'm sure that's not what you're looking for

real grove
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@trim rune What do you mean? I want to cast shorter shadows for objects that are shorter. So a half wall is shorter than a tall wall. What's there not to understand?

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The red line is an illustration of how the shadow could look for a half wall.

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Currently shadows are cast the length of whatever the light can reach. So sorry, if you were not able to understand that, it seems clear to me

real grove
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Nope, no length control

image.png
trim rune
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I completely misunderstood the screen, yes

real grove
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though it seems slightly overkill but seems like there are no good alternatives from my research

trim rune
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I didn't use 2d lighting, but I doubt they have anything built-in for that, unity seems to never finish new features

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So my approach would be:

  1. Research if there is any built-in feature for that (You've done that)
  2. Research the way built-in lighting works and see if there are any hacks/workarounds
  3. Research if there are any github packages created already for custom lighting in 2D games
  4. Make one yourself

~. Stick with 3D lighting with camera twisted by the right angle, so you work with 2d game in 3d space with 3d lighting. Like "enter the gungeon" does

real grove
real grove
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Thanks for the feedback @trim rune

acoustic ploverBOT
#

spiderix thanked Дядя Женя

turbid oriole
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So the big idea behind it, in my case:

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A camera renders only the light colliders and you use that as a global texture in your shaders.

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Your light sources use a specific shader that will raycast from their local center toward the exterior, using the obstacle texture to know if a occlusion occurs.

When they meet a colored pixel (an obstacle), they put their shadow intensity to 1, and for each pixel where there is no more obstacle, they reduce it.

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("pixel" here actually means "raycast step", as you can't do that for every pixel, it would be too costy).

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Those lights are rendered on a separate texture.

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Then your actual game shader uses that light texture as an input and uses it to darken the shadowed areas.

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It's very important that the obstacles are a single draw calls, so you use a special shaders for them (I actually only rendered them on a red channel as it's really a "collider / don't collide bitmask".

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Then for the light sources, you don't have a lot of choices since you need to raycast from the center, it's 1 draw call per light source, and the raycast step will give you performance limitation. The more steps, the more precise the shadows, but also the poorer the performance.

If you have a single moving light source, then it's doable. Above 3-4, it becomes suicid. But, a funky trick: you can bake the lights and render the raycasting result only once if they don't move around.

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At some point I added an "intensity" to the red channel of the obstacles, so pebbles would give small shadows, and large walls would block everything, that's just a bit of maths in the shader.

real grove
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Alright, thanks for the input @turbid oriole currently I think I might either go with https://zhuanlan.zhihu.com/p/439637997 or the 2D world in a 3D world

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知乎专栏
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acoustic ploverBOT
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spiderix thanked xahellz

eternal lichen
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Enable Shadows in Unity:
Make sure that your Project Quality Settings have Shadows enabled. Go to "Edit" > "Project Settings" > "Quality" and ensure that the Shadow Type is set to at least "Hard Shadows" or "Soft Shadows."

Set Up Lights:
Ensure that the lights in your scene are set to cast shadows. Select the light source in the scene, and in the Inspector window, make sure "Cast Shadows" is enabled.

Set Up Shadow Distance:
Each GameObject that casts shadows has a "Shadow" component. You can set the shadow distance individually for each object. Adjust the shadow distance based on the desired length.

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`using UnityEngine;

public class CustomShadowCasting : MonoBehaviour
{
public float shadowDistance = 10f;

void Start()
{
    // Set the shadow distance for this GameObject
    GetComponent<Renderer>().shadowCastingMode = UnityEngine.Rendering.ShadowCastingMode.On;
    GetComponent<Renderer>().receiveShadows = true;
    GetComponent<Renderer>().shadowDistance = shadowDistance;
}

}`

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Attach this script to the GameObjects you want to customize, and you can adjust the shadowDistance parameter in the Inspector.

Dynamic Adjustments:
If you want to dynamically adjust shadow lengths during runtime, you can modify the shadow distance property in your script based on certain conditions.

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`using UnityEngine;

public class DynamicShadowCasting : MonoBehaviour
{
void Update()
{
// Dynamically adjust shadow distance based on some conditions
float dynamicShadowDistance = CalculateDynamicShadowDistance();
GetComponent<Renderer>().shadowDistance = dynamicShadowDistance;
}

float CalculateDynamicShadowDistance()
{
    // Implement your logic to calculate the desired shadow distance dynamically
    return Mathf.Clamp(someDynamicValue, minShadowDistance, maxShadowDistance);
}

}`

hidden tusk
real grove
turbid oriole
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So you don't have the shadow width based on the object proximity, but it's one way to do it!