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#ifndef RENDER_SHAPES_INTERNAL_H
#define RENDER_SHAPES_INTERNAL_H

/*
 * Inside the shapes (shapes.c, shapes_props.c): cell sizes, the painted
 * palette and the building blocks both share. Not for use outside.
 */

#include "render/shapes.h"
#include <stdlib.h>

/*
 * Every surface is subdivided into cells of at most CELL_SIZE so the
 * vertex shader can bend straight edges into hand-drawn lines.
 */
#define CELL_SIZE 0.75f
/* Boxes use a finer cell that divides the 0.5 m building grid, so walls
   that touch share their vertices exactly (no cracks along the seams). */
#define BOX_CELL  0.5f

/* ---------- Palettes (painted, slightly desaturated tones) ---------- */

enum { FACE_BACK, FACE_FRONT, FACE_LEFT, FACE_RIGHT, FACE_BOTTOM, FACE_TOP, FACE_COUNT };

#define CREAM      { 0.93f, 0.88f, 0.76f }
#define EARTH      { 0.52f, 0.36f, 0.22f }
#define TERRACOTTA { 0.88f, 0.52f, 0.30f }

/* Single color for round shapes: the palette's first face. */

typedef struct {
    Vec3  p;      /* on the middle line */
    Vec3  side;   /* across, to the left; longer at corners so the edges stay parallel */
    float along;  /* meters from the start */
} RoadRow;

extern const Vec3 COLOR_BARK;
extern const Vec3 COLOR_LEAVES;
extern const Vec3 COLOR_STEEL;

void shapes_addBox(MeshBuilder *b, Vec3 center, Vec3 size, const Vec3 colors[FACE_COUNT]);
/* A lumpy rock round center (half its size each way), its colour shaded a little. */
void shapes_addRock(MeshBuilder *b, Vec3 center, Vec3 half, unsigned *seed, Vec3 color);
void shapes_addTube(MeshBuilder *b, float base_y, float r_bottom, float r_top, float height,
                    int segments, Vec3 color, bool caps);

/* Box in one color. */
static inline void addBlock(MeshBuilder *b, Vec3 center, Vec3 size, Vec3 color) {
    Vec3 colors[FACE_COUNT];
    for (int f = 0; f < FACE_COUNT; f++) colors[f] = color;
    shapes_addBox(b, center, size, colors);
}

/* The foot of a trunk of radius r standing on the ground at ground_y: flaring
   out towards it (up to top) and roots running into it. A tree and the stump
   left of it get the same foot from the same seed. */
void shapes_addTrunkFoot(MeshBuilder *b, float r, float ground_y, float top, unsigned seed, int segments);
/* The sawn face at the foot of a felled trunk (y = 0). */
void shapes_addCutEnd(MeshBuilder *b, float r);

/* Small deterministic random numbers for scattering shards. */
static inline float scatter(unsigned *seed) {
    *seed = *seed * 1664525u + 1013904223u;
    return (float)(*seed >> 8) / 16777216.0f;
}

/* Height of the ground at a point of the mesh, relative to its origin. */
static inline float groundAt(ShapeGround g, float x, float z) {
    return g.height(g.ctx, g.origin.x + x, g.origin.z + z) - g.origin.y;
}

/* Moves the vertices added since first by m (points and normals). */
static inline void transformSince(MeshBuilder *b, size_t first, Mat4 m) {
    for (size_t v = first; v < b->vertex_count; v++) {
        b->vertices[v].position = mat4_mul_point(m, b->vertices[v].position);
        b->vertices[v].normal = vec3_normalize(mat4_mul_dir(m, b->vertices[v].normal));
    }
}

#endif /* RENDER_SHAPES_INTERNAL_H */