Fry3DX 0.4: an easy 3D modeller

Shapes with live settings, shape editing, knife and hole tools, drawing
shapes onto other objects, combining objects (add / subtract / overlap),
copies, thickness, painting with stickers and layers, a Layout tab, a
Print tab with checks, packed .fry files with autosave, export to GLB,
glTF, FBX, OBJ, 3MF, STL and PLY, folders in Layers, its own crash
screen, and a website for GitHub Pages in docs/.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NMSrd5oe1GpUD7E6d825KP

engine/render/clusters.h

@@ -0,0 +1,45 @@
+#pragma once
+// Clustered lighting: the view frustum is cut into a 3D grid (screen tiles × depth
+// slices) and each cell lists the lights that can reach it, so a pixel only shades
+// the few lights near it. Built on the CPU each frame; no GPU code here, so it is
+// shared by every render backend and testable headless.
+#include <glm/glm.hpp>
+
+#include <cstdint>
+#include <vector>
+
+namespace keel {
+
+struct DynamicLight {
+    glm::vec3 origin{0.0f};
+    float radius = 300.0f;        // light reaches zero here
+    glm::vec3 color{1.0f};        // linear, already scaled by intensity
+    glm::vec3 direction{0, 0, -1}; // spot lights
+    float innerCone = 0.0f;       // spot half-angles in degrees; outerCone 0 = point light
+    float outerCone = 0.0f;
+    bool shadows = false;
+    float size = 0.0f;            // the light's own radius (a bulb, a lamp, a window): softer, wider highlights
+    bool reflector = false;       // a flashlight's beam (spotShape in model.glsl): hot centre, a ring, a dim spill
+    bool spot() const { return outerCone > 0.0f; }
+};
+
+// Must match lights.glsl.
+inline constexpr uint32_t kClusterX = 16, kClusterY = 9, kClusterZ = 24;
+inline constexpr float kClusterNear = 8.0f, kClusterFar = 16384.0f;
+
+struct ClusterView {
+    glm::vec3 origin, forward, right, up; // up is the screen's up (after roll)
+    float tanHalfY = 1.0f, aspect = 1.0f;
+};
+
+struct ClusterGrid {
+    std::vector<glm::uvec2> cells;  // per cell: first index, light count; cell = (z * Y + y) * X + x
+    std::vector<uint32_t> indices;  // light indices, grouped by cell
+};
+
+// Depth slice for a distance along the view direction.
+uint32_t clusterSlice(float depth);
+// Lights past maxIndices total cell entries are dropped (farthest cells last).
+void buildClusters(const ClusterView& view, const std::vector<DynamicLight>& lights, size_t maxIndices, ClusterGrid& out);
+
+} // namespace keel