From 961f8c6d405c9c6fcf9aaf4fb6f199b0e5c60d88 Mon Sep 17 00:00:00 2001
From: Jon Santmyer <jon@jonsantmyer.com>
Date: Thu, 30 Apr 2026 10:06:32 -0400
Subject: add orbit rendering for bodies

---
 assets/shaders/tacmap/body.wgsl | 79 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 assets/shaders/tacmap/body.wgsl

(limited to 'assets/shaders/tacmap/body.wgsl')

diff --git a/assets/shaders/tacmap/body.wgsl b/assets/shaders/tacmap/body.wgsl
new file mode 100644
index 0000000..7156150
--- /dev/null
+++ b/assets/shaders/tacmap/body.wgsl
@@ -0,0 +1,79 @@
+struct InstanceInput {
+    @location(0) position: vec3<f32>,
+    @location(1) radius: f32
+};
+
+struct VertexOutput {
+    @builtin(position) clip_position: vec4<f32>,
+    @location(0) local_position: vec3<f32>
+};
+
+struct CameraUniform {
+    view: mat4x4<f32>,
+    proj: mat4x4<f32>,
+    pos: vec3<f32>,
+    scale: f32
+};
+
+@group(0) @binding(0)
+var<uniform> camera: CameraUniform;
+
+const QUAD_VERTICES = array<vec3<f32>,6>(
+    vec3<f32>(-1.0, -1.0, 0.0),
+    vec3<f32>(-1.0, 1.0 , 0.0),
+    vec3<f32>(1.0,  1.0 , 0.0),
+    vec3<f32>(1.0,  1.0 , 0.0),
+    vec3<f32>(1.0,  -1.0, 0.0),
+    vec3<f32>(-1.0, -1.0, 0.0),
+);
+
+@vertex
+fn vs_main(
+    @builtin(vertex_index) index: u32,
+    instance: InstanceInput
+) -> VertexOutput {
+    var out: VertexOutput;
+
+    let model = QUAD_VERTICES[index];
+    var view = camera.view;
+
+    //Billboard the circle
+    let camera_right = vec3<f32>(view[0][0], view[1][0], view[2][0]);
+    let camera_up = vec3<f32>(view[0][1], view[1][1], view[2][1]);
+    let model_pos = camera_right * model.x +
+                    camera_up * model.y;
+
+    let min_size = 0.025;
+
+    //Scale the world around the camera scale and translate about the camera's
+    //absolute (/target) position
+    let instance_pos = (instance.position - camera.pos) * camera.scale;
+
+    let view_proj = camera.proj * view;
+
+    let center_view_pos = view_proj * vec4<f32>(instance_pos, 1.0);
+    let vertex_view_pos = view_proj * vec4<f32>(instance_pos + (model_pos * instance.radius * camera.scale), 1.0);
+
+    let vertex_dist = length(vertex_view_pos - center_view_pos) / center_view_pos.w;
+    if vertex_dist < min_size {
+        out.clip_position = center_view_pos / center_view_pos.w;
+        out.clip_position += camera.proj * vec4<f32>(model.xy * (min_size / 2.0), 0.0, 0.0);
+    }else{
+        out.clip_position = vertex_view_pos;
+    }
+
+    out.local_position = model;
+
+    return out;
+}
+
+@fragment
+fn fs_main(in: VertexOutput
+) -> @location(0) vec4<f32> {
+    let point_dist = length(in.local_position);
+    var alpha = 1.0;
+    if point_dist > 1.0 {
+        alpha = 0.0;
+    }
+    return vec4<f32>(1.0, 1.0, 1.0, alpha);
+}
-- 
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