From ecec6d23de95423b675bc2960ccd4c3950bb4f5f Mon Sep 17 00:00:00 2001 From: Silas Bartha Date: Sat, 3 May 2025 02:16:02 -0400 Subject: Ported blog post --- content/blog/blacklight_shader/blacklight.png | Bin 846587 -> 0 bytes content/blog/blacklight_shader/index.md | 171 ------------------- content/projects/nix_aurea/index.md | 11 -- public/blog/blacklight_shader/blacklight.png | Bin 0 -> 846587 bytes public/blog/blacklight_shader/index.html | 227 ++++++++++++++++++++++++++ public/index.html | 5 +- public/projects/games/NIX_AVREA/index.html | 26 +++ 7 files changed, 255 insertions(+), 185 deletions(-) delete mode 100644 content/blog/blacklight_shader/blacklight.png delete mode 100644 content/blog/blacklight_shader/index.md delete mode 100644 content/projects/nix_aurea/index.md create mode 100644 public/blog/blacklight_shader/blacklight.png create mode 100644 public/blog/blacklight_shader/index.html create mode 100644 public/projects/games/NIX_AVREA/index.html diff --git a/content/blog/blacklight_shader/blacklight.png b/content/blog/blacklight_shader/blacklight.png deleted file mode 100644 index 2c5caf1..0000000 Binary files a/content/blog/blacklight_shader/blacklight.png and /dev/null differ diff --git a/content/blog/blacklight_shader/index.md b/content/blog/blacklight_shader/index.md deleted file mode 100644 index c5e4b27..0000000 --- a/content/blog/blacklight_shader/index.md +++ /dev/null @@ -1,171 +0,0 @@ -+++ -title = "creating a blacklight shader" -date = 2024-11-29 -[taxonomies] -projects = ["bevy_blacklight_material"] -+++ - -today i wanted to take a bit of time to write about a shader i implemented for my in-progress game project (more on that soon™) - -i wanted to create a "blacklight" effect, where specific lights could reveal part of the base texture. this shader works with **spot lights** only, but could be extended to work with point lights - -![example of shader running, showing hidden writing on a wall](./blacklight.png); - -i wrote this shader in wgsl for a [bevy engine](https://bevyengine.org) project, but it should translate easily to other shading languages - -the finished shader can be found as part of [this repo](https://github.com/soaosdev/bevy_blacklight_material) -## shader inputs - -for this shader, i wanted the following features: -- the number of lights should be dynamic -- the revealed portion of the object should match the area illuminated by each light - - the falloff of the light over distance should match the fading of the object - -for this to work i need the following information about each light: -- position (world space) -- direction (world space) -- range -- inner and outer angle - - these will control the falloff of the light at its edges - - outer angle should be less than pi/2 radians - - inner angle should be less than the outer angle - -i also need some info from the vertex shader: -- position (**world space!**) -- uv - -bevy's default pbr vertex shader provides this information, but as long as you can get this info into your fragment shader you should be good to go - -lastly i'll take a base color texture and a sampler - -with all of that, i can start off the shader by setting up the inputs and fragment entry point: - -```wgsl -#import bevy_pbr::forward_io::VertexOutput; - -struct BlackLight { - position: vec3, - direction: vec3, - range: f32, - inner_angle: f32, - outer_angle: f32, -} - -@group(2) @binding(0) var lights: array; -@group(2) @binding(1) var base_texture: texture_2d; -@group(2) @binding(2) var base_sampler: sampler; - -@fragment -fn fragment( - in: VertexOutput, -) -> @location(0) vec4 { -} -``` -(bevy uses group 2 for custom shader bindings) - -since the number of lights is dynamic, i use a [storage buffer](https://google.github.io/tour-of-wgsl/types/arrays/runtime-sized-arrays/) to store that information - -## shader calculations - -the first thing we'll need to know is how close to looking at the fragment the light source is - -we can get this information using some interesting math: - -```wgsl -let light = lights[0]; -let light_to_fragment_direction = normalize(in.world_position.xyz - light.position); -let light_to_fragment_angle = acos(dot(light.direction, light_to_fragment_direction)); -``` - -the first step of this is taking the dot product of light direction and the direction from the light to the fragment - -since both direction vectors are normalized, the dot product will be between -1.0 and 1.0 - -the dot product of two unit vectors is the cosine of the angle between them ([proof here](https://math.libretexts.org/Bookshelves/Calculus/Calculus_(OpenStax)/12%3A_Vectors_in_Space/12.03%3A_The_Dot_Product#Evaluating_a_Dot_Product)) - -therefore, we take the arccosine of that dot product to get the angle between the light and the fragment - -once we have this angle we can plug it in to a falloff based on the angle properties of the light: - -```wgsl -let angle_inner_factor = light.inner_angle/light.outer_angle; -let angle_factor = linear_falloff_radius(light_to_fragment_angle / light.outer_angle, angle_inner_factor))); -``` -```wgsl -fn linear_falloff_radius(factor: f32, radius: f32) -> f32 { - if factor < radius { - return 1.0; - } else { - return 1.0 - (factor - radius) / (1.0 - radius); - } -} -``` -next, we need to make sure the effect falls off properly over distance - -we can do this by getting the distance from the light to the fragment and normalizing it with the range of the light before plugging that into an inverse square falloff - -we'll use squared distance to avoid expensive and unnecessary square root operations: - -```wgsl -let light_distance_squared = distance_squared(in.world_position.xyz, light.position); -let distance_factor = inverse_falloff_radius(saturate(light_distance_squared / (light.range * light.range)), 0.5); -``` -```wgsl -fn distance_squared(a: vec3f, b: vec3f) -> f32 { - let vec = a - b; - return dot(vec, vec); -} - -fn inverse_falloff(factor: f32) -> f32 { - return pow(1.0 - factor, 2.0); -} - -fn inverse_falloff_radius(factor: f32, radius: f32) -> f32 { - if factor < radius { - return 1.0; - } else { - return inverse_falloff((factor - radius) / (1.0 - radius)); - } -} -``` - -now we'll have a float multiplier between 0.0 and 1.0 for our angle and distance to the light - -we can get the resulting color by multiplying these with the base color texture: - -```wgsl -let base_color = textureSample(base_texture, base_sampler, in.uv); -let final_color = base_color * angle_factor * distance_factor; -``` - -this works for one light, but we need to refactor it to loop over all the provided blacklights: -```wgsl -@fragment -fn fragment( - in: VertexOutput, -) -> @location(0) vec4 { - let base_color = textureSample(base_texture, base_sampler, in.uv); - var final_color = vec4f(0.0, 0.0, 0.0, 0.0); - for (var i = u32(0); i < arrayLength(&lights); i = i+1) { - let light = lights[i]; - - let light_to_fragment_direction = normalize(in.world_position.xyz - light.position); - let light_to_fragment_angle = acos(dot(light.direction, light_to_fragment_direction)); - let angle_inner_factor = light.inner_angle / light.outer_angle; - let angle_factor = linear_falloff_radius(light_to_fragment_angle / light.outer_angle, angle_inner_factor); - - let light_distance_squared = distance_squared(in.world_position.xyz, light.position); - let distance_factor = inverse_falloff_radius(saturate(light_distance_squared / (light.range * light.range)), 0.5); - - final_color = saturate(final_color + base_color * angle_factor * distance_factor); - } - return final_color; -} -``` - -and with that, the shader is pretty much complete - -you can view the full completed shader code [here](https://github.com/soaosdev/bevy_blacklight_material/blob/master/assets/shaders/blacklight_material.wgsl) - -have fun! - diff --git a/content/projects/nix_aurea/index.md b/content/projects/nix_aurea/index.md deleted file mode 100644 index 2c68a6d..0000000 --- a/content/projects/nix_aurea/index.md +++ /dev/null @@ -1,11 +0,0 @@ -+++ -title = "nix_aurea" -[taxonomies] -categories = ["game"] -languages = ["rust"] -[extra] -wip = true -very_cool = true -+++ - -this page is under construction ;) diff --git a/public/blog/blacklight_shader/blacklight.png b/public/blog/blacklight_shader/blacklight.png new file mode 100644 index 0000000..2c5caf1 Binary files /dev/null and b/public/blog/blacklight_shader/blacklight.png differ diff --git a/public/blog/blacklight_shader/index.html b/public/blog/blacklight_shader/index.html new file mode 100644 index 0000000..db4b54e --- /dev/null +++ b/public/blog/blacklight_shader/index.html @@ -0,0 +1,227 @@ + + + + + + + Creating a Blacklight Shader - soaos + + + + Go Home + Go Back +

Creating a Blacklight Shader

+ + NOTE: THIS POST WAS TRANSFERRED FROM MARKDOWN BY HAND SO I MIGHT HAVE MISSED SOME STUFF SORRY + +

today i wanted to take a bit of time to write about a shader i implemented for my in-progress game project (more + on that soon™)

+

i wanted to create a "blacklight" effect, where specific lights could reveal part of the base texture. this + shader works with spot lights only, but could be extended to work with point lights

+
+ Example of shader running, showing hidden writing on a wall +
Example of shader running, showing hidden writing on a wall.
+
+ +

i wrote this shader in wgsl for a bevy engine project, but + it should translate easily to other shading languages

+ +

the finished shader can be found as part of this repo

+ +

shader inputs

+ +

+ for this shader, i wanted the following features: +

    +
  • + the number of lights should be dynamic +
    • +
  • + the revealed portion of the object should match the area illuminated by each light +
    • +
  • + the falloff of the light over distance should match the fading of the object +
    • +
+ + for this to work i need the following information about each light: +
    +
  • + position (world space) +
    • +
  • + direction (world space) +
    • +
  • + range +
    • +
  • + inner and outer angle +
    • +
  • + these will control the falloff of the light at its edges +
    • +
  • + outer angle should be less than pi/2 radians +
    • +
  • + inner angle should be less than the outer angle +
    • +
+ + i also need some info from the vertex shader: +
    +
  • + position (world space!) +
    • +
  • + uv +
    • +
+

+

bevy's default pbr vertex shader provides this information, but as long as you can get this info into your + fragment + shader you should be good to go

+ +

lastly i'll take a base color texture and a sampler

+ +

+ with all of that, i can start off the shader by setting up the inputs and fragment entry point: + + 

+	#import bevy_pbr::forward_io::VertexOutput;
+
+	struct BlackLight {
+		position: vec3<f32>,
+		direction: vec3<f32>,
+		range: f32,
+		inner_angle: f32,
+		outer_angle: f32,
+	}
+
+	@group(2) @binding(0) var<storage> lights: array<BlackLight>;
+	@group(2) @binding(1) var base_texture: texture_2d<f32>;
+	@group(2) @binding(2) var base_sampler: sampler;
+
+	@fragment
+	fn fragment(
+		in: VertexOutput,
+	) -> @location(0) vec4<f32> {
+	}
+
+ (bevy uses group 2 for custom shader bindings) +

+ +

+ since the number of lights is dynamic, i use a storage buffer to store + that information +

+ +

shader calculations

+ +

the first thing we'll need to know is how close to looking at the fragment the light source + is

+ +

+ we can get this information using some interesting math: + + 

+	let light = lights[0];
+	let light_to_fragment_direction = normalize(in.world_position.xyz - light.position);
+	let light_to_fragment_angle = acos(dot(light.direction, light_to_fragment_direction));
+
+ + the first step of this is taking the dot product of light direction and the direction from + the light to the fragment +

+ +

since both direction vectors are normalized, the dot product will be between -1.0 and 1.0

+ +

+ the dot product of two unit vectors is the cosine of the angle between them (proof + here) +

+ +

+ therefore, we take the arccosine of that dot product to get the angle between the light and + the fragment +

+ +

+ once we have this angle we can plug it in to a falloff based on the angle properties of the + light: + + 

+	let angle_inner_factor = light.inner_angle/light.outer_angle;
+	let angle_factor = linear_falloff_radius(light_to_fragment_angle / light.outer_angle, angle_inner_factor);
+
+ 
+	fn linear_falloff_radius(factor: f32, radius: f32) -> f32 {
+		if factor < radius { return 1.0; } else { 
+			return 1.0 - (factor - radius) / (1.0 - radius); 
+		} 
+	}
+
+

+

+ next, we need to make sure the effect falls off properly over distance we can do this by getting the distance + from the light to + the fragment and normalizing it with the range of the light before plugging that into an inverse square falloff + we'll use squared distance to avoid expensive and unnecessary square root operations: + 

+	let light_distance_squared=distance_squared(in.world_position.xyz, light.position);
+	let distance_factor=inverse_falloff_radius(saturate(light_distance_squared / (light.range * light.range)), 0.5);
+
+ 
+	fn distance_squared(a: vec3f, b: vec3f) -> f32 {
+		let vec = a - b;
+		return dot(vec, vec);
+	}
+
+	fn inverse_falloff(factor: f32) -> f32 {
+		return pow(1.0 - factor, 2.0);
+	}
+
+	fn inverse_falloff_radius(factor: f32, radius: f32) -> f32 {
+		if factor < radius { return 1.0; } else { 
+			return inverse_falloff((factor - radius) / (1.0 - radius)); 
+		}
+	}
+
+

+

+ now we'll have a float multiplier between 0.0 and 1.0 for our angle and distance to the light we can get the + resulting color by multiplying these with the base color texture: + 

+	let base_color = textureSample(base_texture, base_sampler, in.uv);
+	let final_color=base_color * angle_factor * distance_factor;
+
+ this works for one light, but we need to refactor it to loop over all the provided blacklights: + 
+
+	@fragment fn fragment( in: VertexOutput ) -> @location(0) vec4<f32> {
+		let base_color = textureSample(base_texture, base_sampler, in.uv);
+		var final_color = vec4f(0.0, 0.0, 0.0, 0.0);
+		for (var i = u32(0); i < arrayLength(&lights); i = i+1) { 
+			let light=lights[i];
+			let light_to_fragment_direction = normalize(in.world_position.xyz - light.position);
+			let light_to_fragment_angle = acos(dot(light.direction, light_to_fragment_direction));
+			let angle_inner_factor = light.inner_angle / light.outer_angle;
+			let angle_factor = linear_falloff_radius(light_to_fragment_angle / light.outer_angle, angle_inner_factor);
+			let light_distance_squared = distance_squared(in.world_position.xyz, light.position);
+			let distance_factor = inverse_falloff_radius(saturate(light_distance_squared / (light.range * light.range)), 0.5);
+			final_color = saturate(final_color + base_color * angle_factor * distance_factor);
+		} 
+		return final_color; 
+	}
+
+ and with that, the shader is pretty much complete you can view the full completed shader code here +

+

have fun!

+ + + \ No newline at end of file diff --git a/public/index.html b/public/index.html index c4224ab..725c752 100644 --- a/public/index.html +++ b/public/index.html @@ -29,14 +29,13 @@

Stuff on this Server (Under Construction)

  • - Projects + Projects
  • Gitea
  • - Blog (I wanna start posting more to my mastodon, might bring this back anyway, POSSE right?) + Blog
  • Things I Like diff --git a/public/projects/games/NIX_AVREA/index.html b/public/projects/games/NIX_AVREA/index.html new file mode 100644 index 0000000..47c914b --- /dev/null +++ b/public/projects/games/NIX_AVREA/index.html @@ -0,0 +1,26 @@ + + + + + + + NIX AVREA + + + + Go Home + Go Back +

    NIX AVREA

    +

    This is a project I've been working on since April 2024. It's probably the longest-running personal project I've ever done and has been a monumental undertaking so far.

    +

    I'm unsure how much I want to reveal about this project while I'm developing it, I want the experience to be as novel as possible once it's out. I think I'll probably stick to posting about it here on my site and the occasional YouTube video until it's closer to ready.

    +

    About the Project

    +

    NIX AVREA is the codename for my first game project. The game is highly experimental and features mechanics that (as far as I know) have never been attempted. The game is centered around dynamic content, using steganographic techniques to embed binary payloads inside of asset files in order to construct the game world from a directory on the player's filesystem.

    +

    There is a ton of stuff that's already implemented for this project and I'll gradually add more to the following directories explaining in-depth some of the components:

    + 
    ++-- mechanics/
++-- design/
++-- narrative/
+
    + + + \ No newline at end of file -- cgit v1.2.3