Major reorg

draw/shaders/source/backdrop_blur.vert

@@ -3,7 +3,7 @@
 // Unified backdrop blur vertex shader.
 // Handles both the 1D separable blur passes (fullscreen triangle, mode 0; used for
 // BOTH the H-pass and V-pass) and the composite pass (instanced unit-quad over
-// Backdrop_Primitive storage buffer, mode 1) for the second PSO of the backdrop bracket.
+// Gaussian_Blur_Primitive storage buffer, mode 1) for the second PSO of the backdrop bracket.
 // The first PSO (downsample) uses backdrop_fullscreen.vert.
 //
 // No vertex buffer for either mode. Mode 0 uses gl_VertexIndex 0..2 for a single
@@ -33,7 +33,7 @@ layout(location = 4) flat out float f_half_feather;
 
 // --- Uniforms (set 1) ---
 // Backdrop pipeline's own uniform block — distinct from the main pipeline's
-// Vertex_Uniforms. `mode` selects between H-blur (0) and V-composite (1).
+// Vertex_Uniforms_2D. `mode` selects between H-blur (0) and V-composite (1).
 layout(set = 1, binding = 0) uniform Uniforms {
     mat4 projection;
     float dpi_scale;
@@ -41,18 +41,18 @@ layout(set = 1, binding = 0) uniform Uniforms {
     vec2 _pad0;
 };
 
-// --- Backdrop primitive storage buffer (set 0) ---
+// --- Gaussian blur primitive storage buffer (set 0) ---
 // 48 bytes, std430-natural layout (no implicit padding). vec4 members are
 // front-loaded so their 16-byte alignment is satisfied without holes; the
 // vec2 and scalar tail packs tight to land the struct at a clean 48-byte
 // stride (a multiple of 16, so the array stride needs no rounding either).
-// Field semantics match the CPU-side Backdrop_Primitive declared in
+// Field semantics match the CPU-side Gaussian_Blur_Primitive declared in
 // levlib/draw/backdrop.odin; keep both in sync.
 //
-// Backdrop primitives are tint-only: outline is intentionally absent. Specialized
+// Gaussian blur primitives are tint-only: outline is intentionally absent. Specialized
 // edge effects (e.g. liquid-glass-style refraction outlines) would be a dedicated
 // primitive type with its own pipeline rather than a flag bit here.
-struct Backdrop_Primitive {
+struct Gaussian_Blur_Primitive {
     vec4 bounds; //  0-15: min_xy, max_xy (world-space)
     vec4 radii; // 16-31: per-corner radii (physical px)
     vec2 half_size; // 32-39: RRect half extents (physical px)
@@ -60,8 +60,8 @@ struct Backdrop_Primitive {
     uint color; // 44-47: tint, packed RGBA u8x4
 };
 
-layout(std430, set = 0, binding = 0) readonly buffer Backdrop_Primitives {
-    Backdrop_Primitive primitives[];
+layout(std430, set = 0, binding = 0) readonly buffer Gaussian_Blur_Primitives {
+    Gaussian_Blur_Primitive primitives[];
 };
 
 void main() {
@@ -82,8 +82,8 @@ void main() {
         f_radii = vec4(0.0);
         f_half_feather = 0.0;
     } else {
-        // ---- Mode 1: V-composite instanced unit-quad over Backdrop_Primitive ----
-        Backdrop_Primitive p = primitives[gl_InstanceIndex];
+        // ---- Mode 1: V-composite instanced unit-quad over Gaussian_Blur_Primitive ----
+        Gaussian_Blur_Primitive p = primitives[gl_InstanceIndex];
 
         // Unit-quad corners for TRIANGLELIST (2 triangles, 6 vertices):
         //   index 0 -> (0,0)   index 3 -> (0,1)