sprite rework

.gitignore

@@ -29,3 +29,4 @@ game.zip
 icon.ico
 steam/
 subprojects/*/
+build_dbg/

scripts/modules/lcdsprite.js

@@ -1,65 +1,107 @@
+/*  Sprite façade (JS) ↔ struct sprite (C)
+ *  The C side exposes per-field getters/setters plus
+ *  `set_affine(m)` which (re)calculates the 2×2 matrix from
+ *  scale / skew / rotation.  
+ *  We mirror every exposed field and make sure the C
+ *  matrix is refreshed whenever one of the three factors
+ *  changes.
+ */
+
 var sprite = {}
 
 var graphics = use('graphics')
-var render = use('render')
-var draw2d = use('draw2d')
+var render   = use('render')
+var draw2d   = use('draw2d')
 
-var ursprite = {}
+var SPRITE  = Symbol()   /* raw C sprite                    */
+var POS     = Symbol()   /* cached JS copies of simple data */
+var ROT     = Symbol()
+var SCALE   = Symbol()
+var SKEW    = Symbol()
+var CENTER  = Symbol()
+var COLOR   = Symbol()
 
-ursprite.move = function move(mv)
-{
-  this.rect.x += mv.x
-  this.rect.y += mv.y
+var ursprite = {
+  get pos()  { return this[POS] },
+  set pos(v) {
+    this[POS]      = v
+    this[SPRITE].pos = v
+  },
+
+  get center() { return this[CENTER] },
+  set center(v){
+    this[CENTER]       = v
+    this[SPRITE].center = v
+  },
+
+  get rotation() { return this[ROT] },
+  set rotation(t){
+    this[ROT]            = t
+    this[SPRITE].rotation = t * 2*Math.PI  /* C expects radians */
+    this[SPRITE].set_affine()
+  },
+
+  get scale() { return this[SCALE] },
+  set scale(v){
+    this[SCALE]       = v
+    this[SPRITE].scale = v
+    this[SPRITE].set_affine()    
+  },
+
+  get skew() { return this[SKEW] },
+  set skew(v){
+    this[SKEW]       = v
+    this[SPRITE].skew = v
+    this[SPRITE].set_affine()
+  },
+
+  get layer() { return this[SPRITE].layer },
+  set layer(n){ this[SPRITE].layer = n },
+
+  get color() { return this[COLOR] },
+  set color(v){
+    this[COLOR]       = v
+    this[SPRITE].color = v
+  },
+
+  move(mv){
+    this.pos = {x:this.pos.x+mv.x, y:this.pos.y+mv.y}
+  },
+  moveto(p){
+    this.pos = p
+  }
 }
 
-ursprite.moveto = function moveto(pos)
-{
-  this.rect.x = pos.x
-  this.rect.y = pos.y
-}
+var _sprites = []
 
-ursprite.draw = function draw()
-{
-  draw2d.image(this.image, this.rect, 0, this.anchor)
-}
+sprite.create = function(image, pos, anchor=[0,0], layer=0, props={}) {
+  var sp         = Object.create(ursprite)
+  var raw        = graphics.make_sprite()
 
-var sprites = []
+  sp[SPRITE] = raw
 
-sprite.create = function(image, pos, anchor = [0,0], layer = 0, props = {})
-{
-  var sp = Object.create(ursprite)
+  sp.pos      = pos
+  sp.rotation = 0
+  sp.scale    = [1,1]
+  sp.skew     = [0,0]
+  sp.center   = anchor
+  sp.color    = [1,1,1,1]
 
-  var image = graphics.texture(image)
-  sp.image = image
-  sp.rect = {x:pos.x, y:pos.y, width: image.texture.width, height: image.texture.height}
-  sp.layer = layer
-  sp.props = props
-  sp.anchor = anchor
+  var tex     = graphics.texture(image)
+  raw.set_image(tex)
+  sp.image    = tex
 
-  sprites.push(sp)
+  sp.layer    = layer
+  sp.props    = props
+  sp.anchor   = anchor
 
+  _sprites.push(sp)
   return sp
 }
 
-sprite.forEach = function(fn)
-{
-  for (var sp of sprites)
-    fn(sp)
-}
-
-sprite.values = function()
-{
-  return sprites.slice()
-}
-
-sprite.geometry = function()
-{
-  return graphics.make_sprite_mesh(sprites)
-}
-
-sprite.queue = function()
-{
-  return graphics.make_sprite_queue(sprites)
-}
+sprite.forEach = fn => { for (let s of _sprites) fn(s) }
+sprite.values  = ()  => _sprites.slice()
+sprite.geometry= ()  => graphics.make_sprite_mesh(_sprites)
+sprite.queue   = ()  => graphics.make_sprite_queue(_sprites)
 
 return sprite

source/jsffi.c

@@ -3034,8 +3034,6 @@ JSC_CCALL(renderer_coords,
 
 JSC_CCALL(renderer_camera,
   renderer_ctx *ctx = js2renderer_ctx(js,self);
-  JSValue camera = argv[0];
-
   ctx->cam = camera_globals(js, argv[0]);
 )
 
@@ -3115,25 +3113,15 @@ JSC_CCALL(renderer_make_sprite_mesh,
   JS_SetProperty(js, ret, count, number2js(js, count));
 )
 
-JSC_CCALL(renderer_texture_9grid,
-  renderer_ctx *ctx = js2renderer_ctx(js, self);
-  SDL_Renderer  *r   = ctx->sdl;
-
-  SDL_Texture *tex = js2SDL_Texture(js, argv[0]);
-
-  rect src = js2rect(js, argv[1]);
-  lrtb extents = js2lrtb(js, argv[2]);
-  float scale = 1;
-
-  rect dst = js2rect(js,argv[3]);
-
-  dst = renderer_worldrect_to_screen(ctx, dst);
-
-  if (!SDL_RenderTexture9Grid(r, tex, &src,
-                              extents.l, extents.r, extents.t, extents.b,
-                              scale, &dst))
-    return JS_ThrowReferenceError(js, "SDL_RenderTexture9Grid: %s", SDL_GetError());
-)
+static sprite js_getsprite(JSContext *js, JSValue sp)
+{
+  sprite *s = js2sprite(js, sp);
+  if (s)
+    return *s;
+  
+  sprite pp = {0};
+  return pp;
+}
 
 JSC_CCALL(renderer_texture,
   renderer_ctx *ctx = js2renderer_ctx(js, self);
@@ -3156,24 +3144,26 @@ JSC_CCALL(renderer_texture,
 
 JSC_CCALL(renderer_sprite,
   renderer_ctx *ctx = js2renderer_ctx(js, self);
-  sprite *sp = js2sprite(js,argv[0]);
-
+  sprite sp = js_getsprite(js, argv[0]);
   SDL_Texture *tex;
-  JS_GETATOM(js, tex, sp->image, texture, SDL_Texture);
+  JS_GETATOM(js, tex, sp.image, texture, SDL_Texture);
 
-//  rect dst = renderer_worldrect_to_screen(ctx, sp->affine);
-  rect dst = sp->affine;
-  rect uv = {x:0,y:0,w:48,h:24};
-  SDL_RenderTexture(ctx->sdl, tex, &uv, &dst);
-)
+  float w = sp.uv.w, h = sp.uv.h;
 
-JSC_CCALL(renderer_slice9,
-  renderer_ctx *ctx = js2renderer_ctx(js, self);
-  SDL_Texture *tex = js2SDL_Texture(js,argv[0]);
-  rect src = js2rect(js, argv[1]);
-  lrtb exts = js2lrtb(js, argv[2]);
-  rect dst = renderer_worldrect_to_screen(ctx, js2rect(js, argv[3]));
-  SDL_RenderTexture9Grid(ctx->sdl, tex, &src, exts.l, exts.r, exts.t, exts.b, 0.0f, &dst);
+  HMM_Vec2 tl_local = { -sp.center.X,        -sp.center.Y        };
+  HMM_Vec2 tr_local = { -sp.center.X + w,    -sp.center.Y        };
+  HMM_Vec2 bl_local = { -sp.center.X,        -sp.center.Y + h    };
+  
+  HMM_Vec2 world_tl = HMM_AddV2(sp.pos, HMM_MulM2V2(sp.affine, tl_local));
+  HMM_Vec2 world_tr = HMM_AddV2(sp.pos, HMM_MulM2V2(sp.affine, tr_local));
+  HMM_Vec2 world_bl = HMM_AddV2(sp.pos, HMM_MulM2V2(sp.affine, bl_local));
+
+  SDL_FPoint origin = renderer_world_to_screen(ctx, world_tl);
+  SDL_FPoint right  = renderer_world_to_screen(ctx, world_tr);
+  SDL_FPoint down   = renderer_world_to_screen(ctx, world_bl);
+
+  if (!SDL_RenderTextureAffine(ctx->sdl, tex, &sp.uv, &origin, &right, &down))
+    return JS_ThrowInternalError(js, "Render sprite error: %s", SDL_GetError());
 )
 
 static const JSCFunctionListEntry js_renderer_ctx_funcs[] = {
@@ -3189,7 +3179,6 @@ static const JSCFunctionListEntry js_renderer_ctx_funcs[] = {
   MIST_FUNC_DEF(renderer, sprite, 1),
   MIST_FUNC_DEF(renderer, load_texture, 1),
   MIST_FUNC_DEF(renderer, get_image, 1),
-  MIST_FUNC_DEF(renderer, slice9, 4),
   
   MIST_FUNC_DEF(renderer, scale, 1),
   MIST_FUNC_DEF(renderer, logical_size,1),
@@ -3263,11 +3252,11 @@ static SDL_AudioSpec js2audiospec(JSContext *js, JSValue obj)
   JS_FreeValue(js, v);
 
   v = JS_GetPropertyStr(js, obj, "channels");
-  if (!JS_IsUndefined(v)) JS_ToUint32(js, &spec.channels, v);
+  if (!JS_IsUndefined(v)) JS_ToInt32(js, &spec.channels, v);
   JS_FreeValue(js, v);
 
   v = JS_GetPropertyStr(js, obj, "samplerate");
-  if (!JS_IsUndefined(v)) JS_ToUint32(js, &spec.freq, v);
+  if (!JS_IsUndefined(v)) JS_ToInt32(js, &spec.freq, v);
   JS_FreeValue(js, v);
 
   return spec;
@@ -3294,7 +3283,7 @@ JSC_CCALL(sdl_audio_devices,
 )
 
 JSC_CCALL(sdl_audio_open_stream,
-  char *type = JS_IsString(argv[0]) ? JS_ToCString(js, argv[0]) : NULL;
+  const char *type = JS_IsString(argv[0]) ? JS_ToCString(js, argv[0]) : NULL;
   SDL_AudioDeviceID devid = !strcmp(type, "capture") ? SDL_AUDIO_DEVICE_DEFAULT_RECORDING : SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK;
 
   if (type)
@@ -4042,11 +4031,11 @@ typedef struct {
 static inline int sprite_compare(const sprite *a, const sprite *b) {
   if (a->layer != b->layer) return a->layer - b->layer;
 
-  if (a->affine.y != b->affine.y)
-    return (b->affine.y - a->affine.y);
+  if (a->pos.Y != b->pos.Y)
+    return (b->pos.Y - a->pos.Y);
 
-  if (a->tex != b->tex)
-    return (a->tex < b->tex) ? -1 : 1;
+  if (JS_VALUE_GET_PTR(a->image) != JS_VALUE_GET_PTR(b->image))
+    return JS_VALUE_GET_PTR(a->image) < JS_VALUE_GET_PTR(b->image) ? -1 : 1;
 
   return 0;
 }
@@ -4087,28 +4076,35 @@ void better_sort_sprites(sprite *arr, size_t length) {
 int sort_sprite_backtofront(const sprite *a, const sprite *b)
 {
   if (a->layer != b->layer) return a->layer - b->layer;
-  if (a->tex != b->tex) return ((uintptr_t)a->tex < (uintptr_t)b->tex) ? -1 : 1;
+  if (JS_VALUE_GET_PTR(a->image) != JS_VALUE_GET_PTR(b->image))
+    return JS_VALUE_GET_PTR(a->image) < JS_VALUE_GET_PTR(b->image) ? -1 : 1;  
   return 0;
 }
 
 int sort_sprite_fronttoback(const sprite *a, const sprite *b)
 {
   if (a->layer != b->layer) return b->layer - a->layer;
-  if (a->tex != b->tex) return ((uintptr_t)a->tex < (uintptr_t)b->tex) ? -1 : 1;
+  if (JS_VALUE_GET_PTR(a->image) != JS_VALUE_GET_PTR(b->image))
+    return JS_VALUE_GET_PTR(a->image) < JS_VALUE_GET_PTR(b->image) ? -1 : 1;  
   return 0;
 }
 
 int sort_sprite_texture(const sprite *a, const sprite *b)
 {
-  if (a->tex != b->tex) return ((uintptr_t)a->tex < (uintptr_t)b->tex) ? -1 : 1;
+  if (JS_VALUE_GET_PTR(a->image) != JS_VALUE_GET_PTR(b->image))
+    return JS_VALUE_GET_PTR(a->image) < JS_VALUE_GET_PTR(b->image) ? -1 : 1;
   return 0;
 }
 
 int sort_sprite(const sprite *a, const sprite *b)
 {
   if (a->layer != b->layer) return a->layer - b->layer;
-  if (a->affine.y != b->affine.y) return b->affine.y - a->affine.y;
-  if (a->tex != b->tex) return ((uintptr_t)a->tex < (uintptr_t)b->tex) ? -1 : 1;
+  
+  if (a->pos.Y != b->pos.Y)
+    return (b->pos.Y - a->pos.Y);
+    
+  if (JS_VALUE_GET_PTR(a->image) != JS_VALUE_GET_PTR(b->image))
+    return JS_VALUE_GET_PTR(a->image) < JS_VALUE_GET_PTR(b->image) ? -1 : 1;  
   return 0;
 }
 
@@ -4139,7 +4135,6 @@ JSC_CCALL(gpu_make_sprite_queue,
   sprite *sprites = NULL;
   size_t quads = 0;
   int needfree = 1;
-  int sort = js2number(js,argv[3]);
 
   if (JS_IsArrayBuffer(js, argv[0])) {
     // test for fastest  
@@ -4162,26 +4157,26 @@ JSC_CCALL(gpu_make_sprite_queue,
       }
       else {
         sprite sp = {0};
-        JS_GETATOM(js,sp.affine, sub, rect, rect)
+        JS_GETATOM(js, sp.pos, sub, pos, vec2)
+        JS_GETATOM(js, sp.center, sub, center, vec2)
+        JS_GETATOM(js, sp.skew, sub, skew, vec2)
+        JS_GETATOM(js, sp.scale, sub, scale, vec2)
         JS_GETATOM(js,sp.color,sub,color,color)
         JS_GETATOM(js,sp.layer,sub,layer,number)
         JS_GETATOM(js,sp.uv,sub,src,rect)
         sp.image = JS_GetProperty(js,sub,image);
-        
-        JS_GETATOM(js,sp.tex,sp.image,texture,SDL_GPUTexture)
         arrput(sprites,sp);
      }
       JS_FreeValue(js, sub);
     }
   }
   
-  if (sort) qsort(sprites, quads, sizeof(sprite), sort_sprite);
-//  else qsort(sprites, quads, sizeof(sprite), sort_sprite_texture);
+  qsort(sprites, quads, sizeof(sprite), sort_sprite);
 
   struct quad_buffers buffers = quad_buffers_new(quads*4);
 
   for (int i = 0; i < quads; i++) {
-    rect pr = sprites[i].affine;
+    rect pr = {0};
     rect uv = sprites[i].uv;
     HMM_Vec4 c = sprites[i].color;
 
@@ -6826,36 +6821,6 @@ JSC_CCALL(os_make_rtree,
   return rtree2js(js,tree);
 )
 
-JSC_CCALL(os_rects_to_sprites,
-  ret = JS_NewArray(js);
-
-  JSValue image = argv[0];
-  JSValue jstex = JS_GetProperty(js,image,texture);
-  double w, h = 0;
-  JS_GETATOM(js,w,jstex,width,number)
-  JS_GETATOM(js,h,jstex,height,number)
-  SDL_GPUTexture *tex = js2SDL_GPUTexture(js,jstex);
-  JS_FreeValue(js,jstex);
-  JSValue rects = argv[1];
-  rect uv;
-  JS_GETATOM(js,uv,image,rect,rect)
-
-  ret = JS_NewArray(js);
-  int n = js_arrlen(js,rects);
-  for (int i = 0; i < n; i++) {
-    JSValue sub = JS_GetPropertyUint32(js,rects,i);
-    sprite *s = make_sprite();
-    s->affine = js2rect(js,sub);
-    s->affine.w = w;
-    s->affine.h = h;
-    s->image = JS_DupValue(js,image);
-    s->tex = tex;
-    s->uv = uv;
-    JS_SetPropertyUint32(js,ret,i,sprite2js(js,s));
-    JS_FreeValue(js,sub);
-  }
-)
-
 JSC_CCALL(os_on,
   prosperon_rt *rt = JS_GetContextOpaque(js);
   JS_FreeValue(js, rt->on_exception);
@@ -6995,7 +6960,7 @@ JSC_CCALL(os_createactor,
 
   for (int i = 0; i < margc; i++) {
     JSValue val = JS_GetPropertyUint32(js, argv[0], i);
-    char *cstr = JS_ToCString(js,val);
+    const char *cstr = JS_ToCString(js,val);
     margv[i] = strdup(cstr);
     JS_FreeCString(js,cstr);
     JS_FreeValue(js,val);
@@ -7018,7 +6983,7 @@ JSC_CCALL(os_mailbox_push,
 
   void *data = value2wota(js, argv[1], JS_UNDEFINED);
   
-  char *err = send_message(id, data);
+  const char *err = send_message(id, data);
   if (err) {
     free(data);
     return JS_ThrowInternalError(js, "Could not send message: %s", err);
@@ -7027,8 +6992,8 @@ JSC_CCALL(os_mailbox_push,
 
 JSC_CCALL(os_register_actor,
   prosperon_rt *rt = JS_GetContextOpaque(js);
-  char *id = JS_ToCString(js, argv[0]);
-  char *err = register_actor(id, rt, JS_ToBool(js, argv[2]));
+  const char *id = JS_ToCString(js, argv[0]);
+  const char *err = register_actor(id, rt, JS_ToBool(js, argv[2]));
   if (err) return JS_ThrowInternalError(js, "Could not register actor: %s", err);
   rt->message_handle = JS_DupValue(js, argv[1]);
   rt->context = js;
@@ -7184,7 +7149,6 @@ static const JSCFunctionListEntry js_graphics_funcs[] = {
   MIST_FUNC_DEF(os, make_gif, 1),
   MIST_FUNC_DEF(os, make_aseprite, 1),
   MIST_FUNC_DEF(os, cull_sprites, 2),
-  MIST_FUNC_DEF(os, rects_to_sprites,2),
   MIST_FUNC_DEF(os, make_surface, 1),
   MIST_FUNC_DEF(os, make_cursor, 1),
   MIST_FUNC_DEF(os, make_font, 2),
@@ -7390,19 +7354,17 @@ static const JSCFunctionListEntry js_rtree_funcs[] = {
   MIST_FUNC_DEF(rtree,values,0),
 };
 
+JSC_GETSET(sprite, pos, vec2)
+JSC_GETSET(sprite, center, vec2)
 JSC_GETSET(sprite, layer, number)
 JSC_GETSET(sprite, color, color)
+JSC_GETSET(sprite, skew, vec2)
+JSC_GETSET(sprite, scale, vec2)
+JSC_GETSET(sprite, rotation, number)
 
 JSC_CCALL(sprite_set_affine,
   sprite *sp = js2sprite(js,self);
-  transform *t = js2transform(js,argv[0]);
-  if (t)
-    sp->affine = transform2rect(t);
-)
-
-JSC_CCALL(sprite_set_rect,
-  sprite *sp = js2sprite(js,self);
-  sp->affine = js2rect(js,argv[0]);
+  sprite_apply(sp);
 )
 
 JSC_CCALL(sprite_set_image,
@@ -7413,13 +7375,15 @@ JSC_CCALL(sprite_set_image,
   if (JS_IsUndefined(sp->image)) return JS_UNDEFINED;
   JSValue img = sp->image;
   JS_GETATOM(js, sp->uv, img, rect, rect)
-  JS_GETATOM(js, sp->tex, img, texture, SDL_GPUTexture);
 )
 
 static const JSCFunctionListEntry js_sprite_funcs[] = {
-  MIST_FUNC_DEF(sprite, set_affine, 1),
-  MIST_FUNC_DEF(sprite, set_rect, 1),
+  MIST_FUNC_DEF(sprite, set_affine, 0),
   MIST_FUNC_DEF(sprite, set_image, 1),
+  CGETSET_ADD(sprite, skew),
+  CGETSET_ADD(sprite, rotation),
+  CGETSET_ADD(sprite, pos),
+  CGETSET_ADD(sprite, center),
   CGETSET_ADD(sprite, layer),
   CGETSET_ADD(sprite, color),
 };
@@ -7563,8 +7527,8 @@ void ffi_load(JSContext *js)
     JS_SetPropertyUint32(js,args, i, JS_NewString(js,rt->cmd.argv[i]));
 
   JS_SetPropertyStr(js,prosp,"argv", args);
-  JS_SetPropertyStr(js,prosp, "version", JS_NewString(js,PROSPERON_VERSION));
-  JS_SetPropertyStr(js,prosp,"revision",JS_NewString(js,PROSPERON_COMMIT));
+  //JS_SetPropertyStr(js,prosp, "version", JS_NewString(js,PROSPERON_VERSION));
+  //JS_SetPropertyStr(js,prosp,"revision",JS_NewString(js,PROSPERON_COMMIT));
   JS_SetPropertyStr(js,prosp,"engine_start", JS_NewCFunction(js,js_os_engine_start, "engine_start", 1));
 
   JS_FreeValue(js,globalThis);

source/prosperon.c

@@ -238,7 +238,7 @@ prosperon_rt *get_actor(char *id)
   return actor;
 }
 
-char *register_actor(char *id, prosperon_rt *actor, int mainthread)
+const char *register_actor(const char *id, prosperon_rt *actor, int mainthread)
 {
   if (shgeti(actors, id) != -1) return "Actor with given ID already exists.";
   actor->main_thread_only = mainthread;
@@ -249,7 +249,7 @@ char *register_actor(char *id, prosperon_rt *actor, int mainthread)
   return NULL;
 }
 
-char *send_message(char *id, void *msg)
+const char *send_message(const char *id, void *msg)
 {
   prosperon_rt *target = get_actor(id);
   if (!target) return "Could not get actor from id.";
@@ -1425,7 +1425,7 @@ int main(int argc, char **argv)
   return 0;
 }
 
-int actor_exists(char *id)
+int actor_exists(const char *id)
 {
   int idx = shgeti(actors,id);
   if (idx == -1)

source/prosperon.h

@@ -71,9 +71,9 @@ extern SDL_ThreadID main_thread;
 extern SDL_TLSID prosperon_id;
 
 prosperon_rt *create_actor(int argc, char **argv);
-char *register_actor(char *id, prosperon_rt *actor, int mainthread);
+const char *register_actor(const char *id, prosperon_rt *actor, int mainthread);
 void actor_free(prosperon_rt *actor);
-char *send_message(char *id, void *msg);
+const char *send_message(const char *id, void *msg);
 Uint32 actor_timer_cb(prosperon_rt *actor, SDL_TimerID id, Uint32 interval);
 JSValue js_actor_delay(JSContext *js, JSValue self, int argc, JSValue *argv);
 JSValue js_actor_removetimer(JSContext *js, JSValue self, int argc, JSValue *argv);
@@ -81,7 +81,7 @@ void script_startup(prosperon_rt *rt);
 void script_evalf(JSContext *js, const char *format, ...);
 JSValue script_eval(JSContext *js, const char *file, const char *script);
 int uncaught_exception(JSContext *js, JSValue v);
-int actor_exists(char *id);
+int actor_exists(const char *id);
 void set_actor_state(prosperon_rt *actor);
 
 int prosperon_mount_core(void);

source/qjs_enet.c

@@ -371,7 +371,7 @@ static JSClassDef enet_peer_class = {
 JSValue js_enet_resolve_hostname(JSContext *js, JSValue self, int argc, JSValue *argv)
 {
   // TODO: implement
-  char *hostname = JS_ToCString(js, argv[0]);
+  const char *hostname = JS_ToCString(js, argv[0]);
   JS_FreeCString(js, hostname);
   return JS_UNDEFINED;
 }

source/sprite.c

@@ -1,17 +1,8 @@
 #include "sprite.h"
 
-static sprite model = {
-  .affine = {.x = 0, .y = 0, .w = 0, .h = 0},
-  .tex = NULL,
-  .uv = {.x = 0, .y = 0, .w = 1, .h = 1},
-  .layer = 0,
-  .color = {1, 1, 1, 1}
-};
-
 sprite *make_sprite(void)
 {
-  sprite *sprite = malloc(sizeof(*sprite));
-  *sprite = model;
+  sprite *sprite = calloc(sizeof(*sprite),1);
   sprite->image = JS_UNDEFINED;
   return sprite;
 }
@@ -21,3 +12,21 @@ void sprite_free(JSRuntime *rt, sprite *sprite)
   JS_FreeValueRT(rt,sprite->image);
   free(sprite);
 }
+
+void sprite_apply(sprite *sp)
+{
+  float        rot = sp->rotation;
+  HMM_Vec2     k   = sp->skew;
+  HMM_Vec2     s   = sp->scale;
+
+  float c = cosf(rot),  si = sinf(rot);
+
+  sp->affine.Columns[0] = (HMM_Vec2){
+    .x = (c  + k.x * si) * s.x,
+    .y = (k.y * c + si) * s.x
+  };
+  sp->affine.Columns[1] = (HMM_Vec2){
+    .x = (-si + k.x * c) * s.y,
+    .y = (-k.y * si + c) * s.y
+  };
+}

source/sprite.h

@@ -7,10 +7,12 @@
 
 struct sprite{
   HMM_Vec2 pos; // x,y coordinates of the sprite
-  HMM_Mat2 affine_m; // defines all deformation
-  rect affine; // 
+  HMM_Vec2 center;
+  HMM_Vec2 skew;
+  HMM_Vec2 scale;
+  float rotation;
+  HMM_Mat2 affine;
   JSValue image; // the actual texture resource - perhaps SDL_GPUTexture, or SDL_Texture, or something else ...
-  SDL_GPUTexture *tex;
   rect uv; // pixel coordinates of the sprite on its image
   int layer; // layer this sprite draws onto
   HMM_Vec4 color; // color in 0-1f
@@ -20,5 +22,6 @@ typedef struct sprite sprite;
 
 sprite *make_sprite(void);
 void sprite_free(JSRuntime *rt, sprite *sprite);
+void sprite_apply(sprite *sprite);
 
 #endif