cell/source/qjs_geometry.c

#include "qjs_geometry.h"
#include "jsffi.h"
#include "qjs_macros.h"

#include <SDL3/SDL.h>
#include <math.h>
#include "HandmadeMath.h"
#include "prosperon.h"
#include "font.h"


// GEOMETRY FUNCTIONS

JSC_CCALL(geometry_rect_intersection,
  rect a = js2rect(js,argv[0]);
  rect b = js2rect(js,argv[1]);
  rect c;
  SDL_GetRectIntersectionFloat(&a, &b, &c);
  return rect2js(js,c);
)

JSC_CCALL(geometry_rect_intersects,
  rect a = js2rect(js,argv[0]);
  rect b = js2rect(js,argv[1]);
  return JS_NewBool(js, SDL_HasRectIntersectionFloat(&a,&b));
)

JSC_CCALL(geometry_rect_inside,
  rect inner = js2rect(js,argv[0]);
  rect outer = js2rect(js,argv[1]);
  return JS_NewBool(js,
         inner.x >= outer.x &&
         inner.x + inner.w <= outer.x + outer.w &&
         inner.y >= outer.y &&
         inner.y + inner.h <= outer.y + outer.h
         );
)

JSC_CCALL(geometry_rect_random,
  rect a = js2rect(js,argv[0]);
  return vec22js(js,(HMM_Vec2){
    a.x + rand_range(js,-0.5,0.5)*a.w,
    a.y + rand_range(js,-0.5,0.5)*a.h
  });
)

JSC_CCALL(geometry_rect_point_inside,
  rect a = js2rect(js,argv[0]);
  HMM_Vec2 p = js2vec2(js,argv[1]);
  return JS_NewBool(js,p.x >= a.x && p.x <= a.x+a.w && p.y <= a.y+a.h && p.y >= a.y);
)

JSC_CCALL(geometry_cwh2rect,
  HMM_Vec2 c = js2vec2(js,argv[0]);
  HMM_Vec2 wh = js2vec2(js,argv[1]);
  rect r;
  r.x = c.x;
  r.y = c.y;
  r.w = wh.x;
  r.h = wh.y;
  return rect2js(js,r);
)

JSC_CCALL(geometry_rect_pos,
  rect r = js2rect(js,argv[0]);
  return vec22js(js,(HMM_Vec2){
    .x = r.x,
    .y = r.y
  });
)

JSC_CCALL(geometry_rect_move,
  rect r = js2rect(js,argv[0]);
  HMM_Vec2 move = js2vec2(js,argv[1]);
  r.x += move.x;
  r.y += move.y;
  return rect2js(js,r);
)

JSC_CCALL(geometry_rect_expand,
  rect a = js2rect(js,argv[0]);
  rect b = js2rect(js,argv[1]);
  rect c = {0};
  c.x = fmin(a.x,b.x);
  c.y = fmin(a.y,b.y);
  c.w = fmax(a.x+a.w,b.x+b.w);
  c.h = fmax(a.y+a.h,b.y+b.h);
  return rect2js(js,c);
)

// Helper functions for geometry operations



static inline void add_quad(text_vert **verts, rect *restrict src, rect *restrict dst)
{
  text_vert v = (text_vert){
    .pos = (HMM_Vec2){dst->x, dst->y},
    .uv = (HMM_Vec2){src->x,src->y},
    .color = (HMM_Vec4){1,1,1,1}
  };
  arrput(*verts, v);

  v = (text_vert){
    .pos = (HMM_Vec2){dst->x+dst->w, dst->y},
    .uv = (HMM_Vec2){src->x+src->w,src->y},
    .color = (HMM_Vec4){1,1,1,1}
  };
  arrput(*verts, v);

  v = (text_vert){
    .pos = (HMM_Vec2){dst->x, dst->y+dst->h},
    .uv = (HMM_Vec2){src->x,src->y+src->h},
    .color = (HMM_Vec4){1,1,1,1}
  };
  arrput(*verts, v);

  v = (text_vert){
    .pos = (HMM_Vec2){dst->x+dst->w, dst->y+dst->h},
    .uv = (HMM_Vec2){src->x+src->w,src->y+src->h},
    .color = (HMM_Vec4){1,1,1,1}
  };
  arrput(*verts, v);
}

static inline void tile_region(text_vert **verts, rect src_uv, rect dst, float tex_w, float tex_h, bool tile_x, bool tile_y)
{
  // Convert the incoming UV rect into pixel coords
  rect src_px = {
    .x = src_uv.x * tex_w,
    .y = src_uv.y * tex_h,
    .w = src_uv.w * tex_w,
    .h = src_uv.h * tex_h
  };

  // If src_px or dst is degenerate, early out
  if (src_px.w <= 0.0f || src_px.h <= 0.0f || dst.w <= 0.0f || dst.h <= 0.0f)
    return;

  // How many full tiles horizontally/vertically?
  // If not tiling in a dimension, we treat it as exactly 1 tile (no leftover).
  float cols_f, rows_f;
  float remain_wf = 0.0f;
  float remain_hf = 0.0f;

  if (tile_x) {
    remain_wf = modff(dst.w / src_px.w, &cols_f);
  } else {
    // Only 1 "column" covering entire width, no leftover
    cols_f = 1.0f;
    remain_wf = 0.0f;
  }

  if (tile_y) {
    remain_hf = modff(dst.h / src_px.h, &rows_f);
  } else {
    // Only 1 "row" covering entire height, no leftover
    rows_f = 1.0f;
    remain_hf = 0.0f;
  }

  int cols = (int)cols_f;
  int rows = (int)rows_f;

  // The leftover portion in screen coords (pixels)
  float remain_dst_w = remain_wf * src_px.w;
  float remain_dst_h = remain_hf * src_px.h;

  // Build the UV rect for a "full" tile
  rect src_full = src_uv;

  // Partial leftover in UV
  float remain_src_w_uv = remain_dst_w / tex_w;
  float remain_src_h_uv = remain_dst_h / tex_h;

  // For partial leftover in X dimension
  rect src_partial_x = src_full;
  src_partial_x.w = remain_src_w_uv;

  // For partial leftover in Y dimension
  rect src_partial_y = src_full;
  src_partial_y.h = remain_src_h_uv;

  // For partial leftover in both X & Y
  rect src_partial_xy = src_full;
  src_partial_xy.w = remain_src_w_uv;
  src_partial_xy.h = remain_src_h_uv;

  // Each tile is drawn 1:1 in screen coords
  float tile_w = tile_x ? src_px.w : dst.w;  // If not tiling horizontally, match the entire dst width
  float tile_h = tile_y ? src_px.h : dst.h;  // If not tiling vertically, match the entire dst height

  rect curr_dst;
  curr_dst.w = tile_w;
  curr_dst.h = tile_h;
  curr_dst.y = dst.y;

  // Loop over rows
  for (int y = 0; y < rows; y++) {
    curr_dst.x = dst.x;

    // Loop over columns
    for (int x = 0; x < cols; x++) {
      add_quad(verts, &src_full, &curr_dst);
      curr_dst.x += tile_w;
    }

    // Right-side leftover tile (only if tile_x is true)
    if (tile_x && remain_dst_w > 0.0f) {
      rect partial_dst = {
        .x = curr_dst.x, .y = curr_dst.y,
        .w = remain_dst_w, .h = tile_h
      };
      add_quad(verts, &src_partial_x, &partial_dst);
    }
    curr_dst.y += tile_h;
  }

  // Bottom leftover row (only if tile_y is true)
  if (tile_y && remain_dst_h > 0.0f) {
    rect partial_row_dst;
    partial_row_dst.w = tile_w;
    partial_row_dst.h = remain_dst_h;
    partial_row_dst.y = curr_dst.y;
    partial_row_dst.x = dst.x;

    // Full columns in leftover row
    for (int x = 0; x < cols; x++) {
      add_quad(verts, &src_partial_y, &partial_row_dst);
      partial_row_dst.x += tile_w;
    }

    // Partial leftover corner (both X & Y leftover)
    if (tile_x && remain_dst_w > 0.0f) {
      rect partial_corner_dst = {
        .x = partial_row_dst.x, .y = partial_row_dst.y,
        .w = remain_dst_w,     .h = remain_dst_h
      };
      add_quad(verts, &src_partial_xy, &partial_corner_dst);
    }
  }
}


JSC_CCALL(gpu_slice9,
  JSValue jstex = argv[0];
  rect dst = js2rect(js, argv[1]);

  // Full texture in UV coords
  rect src = {
    .x = 0, .y = 0,
    .w = 1, .h = 1
  };

  // The "slice" LRTB in PIXELS, but we convert to UV below
  lrtb src_slice = js2lrtb(js, argv[2]);
  lrtb dst_slice = src_slice;

  HMM_Vec2 size;
  JS_GETPROP(js, size.x, jstex, width,  number)
  JS_GETPROP(js, size.y, jstex, height, number)
  
  JSValue info = argv[3];
  int tile_top, tile_bottom, tile_left, tile_right, center_x, center_y;
  JS_GETPROP(js,tile_top, info, tile_top, bool)
  JS_GETPROP(js,tile_bottom,info,tile_bottom,bool)
  JS_GETPROP(js,tile_left,info,tile_left,bool)  
  JS_GETPROP(js,tile_right,info,tile_right,bool)
  JS_GETPROP(js, center_x, info, tile_center_x, bool)
  JS_GETPROP(js, center_y, info, tile_center_y, bool)
  
  // Convert the slice edges from pixel to UV
  src_slice.l /= size.x;
  src_slice.r /= size.x;
  src_slice.t /= size.y;
  src_slice.b /= size.y;

  text_vert *verts = NULL;
  rect curr_src;
  rect curr_dst;

  // bottom-left corner (single quad)
  curr_src = src;
  curr_src.w = src_slice.l;
  curr_src.h = src_slice.b;

  curr_dst = dst;
  curr_dst.w = dst_slice.l;
  curr_dst.h = dst_slice.b;
  add_quad(&verts, &curr_src, &curr_dst);

  // top-left corner (single quad)
  curr_src = src;
  curr_src.x = src.x;
  curr_src.y = src.y + src.h - src_slice.t;
  curr_src.w = src_slice.l;
  curr_src.h = src_slice.t;

  curr_dst = dst;
  curr_dst.x = dst.x;
  curr_dst.y = dst.y + dst.h - dst_slice.t;
  curr_dst.w = dst_slice.l;
  curr_dst.h = dst_slice.t;
  add_quad(&verts, &curr_src, &curr_dst);

  // bottom-right corner (single quad)
  curr_src = src;
  curr_src.x = src.x + src.w - src_slice.r;
  curr_src.y = src.y;
  curr_src.w = src_slice.r;
  curr_src.h = src_slice.b;

  curr_dst = dst;
  curr_dst.x = dst.x + dst.w - dst_slice.r;
  curr_dst.y = dst.y;
  curr_dst.w = dst_slice.r;
  curr_dst.h = dst_slice.b;
  add_quad(&verts, &curr_src, &curr_dst);

  // top-right corner (single quad)
  curr_src = src;
  curr_src.x = src.x + src.w - src_slice.r;
  curr_src.y = src.y + src.h - src_slice.t;
  curr_src.w = src_slice.r;
  curr_src.h = src_slice.t;

  curr_dst = dst;
  curr_dst.x = dst.x + dst.w - dst_slice.r;
  curr_dst.y = dst.y + dst.h - dst_slice.t;
  curr_dst.w = dst_slice.r;
  curr_dst.h = dst_slice.t;
  add_quad(&verts, &curr_src, &curr_dst);

  // left bar (tiled)
  curr_src = src;
  curr_src.x = src.x;
  curr_src.y = src.y + src_slice.b;
  curr_src.w = src_slice.l;
  curr_src.h = src.h - src_slice.t - src_slice.b;

  curr_dst = dst;
  curr_dst.x = dst.x;
  curr_dst.y = dst.y + dst_slice.b;
  curr_dst.w = dst_slice.l;
  curr_dst.h = dst.h - dst_slice.t - dst_slice.b;
  tile_region(&verts, curr_src, curr_dst, size.x, size.y,tile_left,tile_left);

  // right bar (tiled)
  curr_src = src;
  curr_src.x = src.x + src.w - src_slice.r;
  curr_src.y = src.y + src_slice.b;
  curr_src.w = src_slice.r;
  curr_src.h = src.h - src_slice.t - src_slice.b;

  curr_dst = dst;
  curr_dst.x = dst.x + dst.w - dst_slice.r;
  curr_dst.y = dst.y + dst_slice.b;
  curr_dst.w = dst_slice.r;
  curr_dst.h = dst.h - dst_slice.t - dst_slice.b;
  tile_region(&verts, curr_src, curr_dst, size.x, size.y,tile_right,tile_right);

  // bottom bar (tiled)
  curr_src = src;
  curr_src.x = src.x + src_slice.l;
  curr_src.y = src.y;
  curr_src.w = src.w - src_slice.l - src_slice.r;
  curr_src.h = src_slice.b;

  curr_dst = dst;
  curr_dst.x = dst.x + dst_slice.l;
  curr_dst.y = dst.y;
  curr_dst.w = dst.w - dst_slice.l - dst_slice.r;
  curr_dst.h = dst_slice.b;
  tile_region(&verts, curr_src, curr_dst, size.x, size.y,tile_bottom,tile_bottom);

  // top bar (tiled)
  curr_src = src;
  curr_src.x = src.x + src_slice.l;
  curr_src.y = src.y + src.h - src_slice.t;
  curr_src.w = src.w - src_slice.l - src_slice.r;
  curr_src.h = src_slice.t;

  curr_dst = dst;
  curr_dst.x = dst.x + dst_slice.l;
  curr_dst.y = dst.y + dst.h - dst_slice.t;
  curr_dst.w = dst.w - dst_slice.l - dst_slice.r;
  curr_dst.h = dst_slice.t;
  tile_region(&verts, curr_src, curr_dst, size.x, size.y,tile_top,tile_top);

  // center (tiled)
  curr_src = src;
  curr_src.x = src.x + src_slice.l;
  curr_src.y = src.y + src_slice.b;
  curr_src.w = src.w - src_slice.l - src_slice.r;
  curr_src.h = src.h - src_slice.t - src_slice.b;

  curr_dst = dst;
  curr_dst.x = dst.x + dst_slice.l;
  curr_dst.y = dst.y + dst_slice.b;
  curr_dst.w = dst.w - dst_slice.l - dst_slice.r;
  curr_dst.h = dst.h - dst_slice.t - dst_slice.b;
  tile_region(&verts, curr_src, curr_dst, size.x, size.y, center_x,center_y);

  JSValue mesh = quads_to_mesh(js, verts);
  arrfree(verts);
  ret = mesh;
)

JSC_CCALL(gpu_tile,
  HMM_Vec2 size;
  JSValue jstex = argv[0];
  JS_GETATOM(js,size.x,jstex,width,number)
  JS_GETATOM(js, size.y, jstex, height, number)

  rect src_pixels = js2rect(js, argv[1]); // 'src' as pixel dimensions
  rect dst = js2rect(js, argv[2]);        // 'dst' as screen coords
  
  int tilex, tiley;
  JSValue jstile = argv[3];
  JS_GETPROP(js,tilex,jstile,repeat_x,bool)
  JS_GETPROP(js,tiley,jstile,repeat_y,bool)
  
  text_vert *verts = NULL;
  tile_region(&verts, src_pixels, dst, size.x, size.y,tilex,tiley);
  ret = quads_to_mesh(js,verts);
  arrfree(verts);
)

static const JSCFunctionListEntry js_geometry_funcs[] = {
  MIST_FUNC_DEF(geometry, rect_intersection, 2),
  MIST_FUNC_DEF(geometry, rect_intersects, 2),
  MIST_FUNC_DEF(geometry, rect_expand, 2),
  MIST_FUNC_DEF(geometry, rect_inside, 2),
  MIST_FUNC_DEF(geometry, rect_random, 1),
  MIST_FUNC_DEF(geometry, cwh2rect, 2),
  MIST_FUNC_DEF(geometry, rect_point_inside, 2),
  MIST_FUNC_DEF(geometry, rect_pos, 1),
  MIST_FUNC_DEF(geometry, rect_move, 2),
  MIST_FUNC_DEF(gpu, tile, 4),
  MIST_FUNC_DEF(gpu, slice9, 3),
};

JSValue js_geometry_use(JSContext *js) {
  JSValue mod = JS_NewObject(js);
  JS_SetPropertyFunctionList(js,mod,js_geometry_funcs,countof(js_geometry_funcs));
  return mod;
}