refactor: move common/shaders/ to src/shaders/

Relocates shared WGSL shaders under src/ where all source code lives,
eliminating the top-level common/ directory.

- Update asset references in workspaces/main/assets.txt and workspaces/test/assets.txt
- Update docs: PROJECT_CONTEXT.md, ARCHITECTURE.md, WORKSPACE_SYSTEM.md, SHADER_REUSE_INVESTIGATION.md

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/src/shaders/camera_common.wgsl b/src/shaders/camera_common.wgsl
new file mode 100644
index 0000000..846d052
--- /dev/null
+++ b/src/shaders/camera_common.wgsl
@@ -0,0 +1,52 @@
+// Camera parameters and helpers for SDF raymarching effects
+
+struct CameraParams {
+    inv_view: mat4x4f,
+    fov: f32,
+    near_plane: f32,
+    far_plane: f32,
+    aspect_ratio: f32,
+}
+
+struct Ray {
+    origin: vec3f,
+    direction: vec3f,
+}
+
+// Generate camera ray for given UV coordinates (-1 to 1)
+fn getCameraRay(cam: CameraParams, uv: vec2f) -> Ray {
+    let cam_pos = vec3f(cam.inv_view[3].x, cam.inv_view[3].y, cam.inv_view[3].z);
+
+    // Compute ray direction from FOV and aspect ratio
+    let tan_fov = tan(cam.fov * 0.5);
+    let ndc = vec3f(uv.x * cam.aspect_ratio * tan_fov, uv.y * tan_fov, -1.0);
+
+    // Transform direction by inverse view matrix (rotation only)
+    let dir = normalize(
+        cam.inv_view[0].xyz * ndc.x +
+        cam.inv_view[1].xyz * ndc.y +
+        cam.inv_view[2].xyz * ndc.z
+    );
+
+    return Ray(cam_pos, dir);
+}
+
+// Extract camera position from inverse view matrix
+fn getCameraPosition(cam: CameraParams) -> vec3f {
+    return vec3f(cam.inv_view[3].x, cam.inv_view[3].y, cam.inv_view[3].z);
+}
+
+// Extract camera forward vector (view direction)
+fn getCameraForward(cam: CameraParams) -> vec3f {
+    return -normalize(vec3f(cam.inv_view[2].x, cam.inv_view[2].y, cam.inv_view[2].z));
+}
+
+// Extract camera up vector
+fn getCameraUp(cam: CameraParams) -> vec3f {
+    return normalize(vec3f(cam.inv_view[1].x, cam.inv_view[1].y, cam.inv_view[1].z));
+}
+
+// Extract camera right vector
+fn getCameraRight(cam: CameraParams) -> vec3f {
+    return normalize(vec3f(cam.inv_view[0].x, cam.inv_view[0].y, cam.inv_view[0].z));
+}