twn_draw: texture_region option for draw_billboard()

apps/demos/scenery/scenes/ingame.c

@@ -179,6 +179,7 @@ static void draw_terrain(SceneIngame *scn) {
             draw_billboard("/assets/grasses/10.png",
                           (Vec3){ (float)x, d0 + 0.15f, (float)y },
                           (Vec2){0.3f, 0.3f},
+                          NULL,
                           (Color){255, 255, 255, 255}, true);
         }
     }

apps/twnlua/.gitignore

@@ -1 +1,2 @@
 luabind.c
+data/scripts/twnapi.lua

apps/twnlua/bindgen.py

@@ -151,15 +151,12 @@ for typename, typedesc in used_converters.items():
 
 
 print('\n'.join(storages))
-print("extern void bindgen_init(void);\n")
-print("void bindgen_init(void) {\n" + '\n'.join(initializers) + "\n}\n")
 print('\n'.join(converters))
 print('\n'.join(bindings))
 
 
 loader = "extern void bindgen_load_%s(lua_State *L);\n" % api["name"]
 loader += "void bindgen_load_%s(lua_State *L) {\n" % api["name"]
-loader += "    bindgen_init();\n"
 for procedure, procedure_desc in api["procedures"].items():
     loader += "    lua_pushcfunction(L, binding_%s);\n" % procedure
     loader += "    lua_setglobal(L, \"%s\");\n" % procedure

apps/twnlua/data/scripts/game.lua

@@ -4,16 +4,39 @@ offset = { x = 0, y = 0 }
 angle = 0
 
 function game_tick()
+    if ctx.udata == nil then
+        ctx.udata = {
+            frame_count = 0,
+            nest = {
+                frame_count = 0,
+            },
+            arr = { [0] = 0 },
+        }
+    end
+
+    draw_text {
+        string = tostring(ctx.udata.frame_count),
+        position = { x = 0, y = 0 },
+        font = "/fonts/kenney-pixel.ttf",
+    }
+
+    draw_text {
+        string = tostring(ctx.udata.nest.frame_count),
+        position = { x = 0, y = 14 },
+        font = "/fonts/kenney-pixel.ttf",
+    }
+
+    draw_text {
+        string = tostring(ctx.udata.arr[0]),
+        position = { x = 0, y = 28 },
+        font = "/fonts/kenney-pixel.ttf",
+    }
+
     input_action {
         name = "press",
         control = "A"
     }
 
-    draw_rectangle {
-        rect = { x = 0, y = 0, w = 640, h = 360 },
-        color = { r = 127, g = 0, b = 127, a = 255 },
-    }
-
     draw_sprite {
         texture = "/assets/title.png",
         rect = {
@@ -32,6 +55,10 @@ function game_tick()
         }
     end
 
+    ctx.udata.frame_count = ctx.udata.frame_count + 1
+    ctx.udata.nest.frame_count = ctx.udata.nest.frame_count + 1
+    ctx.udata.arr[0] = ctx.udata.arr[0] + 1
+
     offset.x = ORIGIN.x + (math.cos(angle) * RADIUS)
     offset.y = ORIGIN.y + (math.sin(angle) * RADIUS)
     angle = angle + 0.1

apps/twnlua/data/twn.toml

@@ -6,5 +6,6 @@ dev_id = "somebody"
 
 [game]
 resolution = [ 640, 360 ]
+background_color = [ 127, 0, 127, 255 ]
 
 [engine]

apps/twnlua/game.c

@@ -1,5 +1,6 @@
 #include "twn_game_api.h"
 
+/* TODO: actually move it back it its own file, it doesn't give any compilation benefits */
 #define LUA_IMPL
 #include "minilua.h"
 
@@ -8,6 +9,8 @@
 
 #include <SDL2/SDL.h>
 
+#define UDATA_NESTING_LIMIT 128
+
 
 /* generated by bindgen.py */
 void bindgen_load_twn(lua_State *L);
@@ -100,6 +103,47 @@ static void *custom_alloc(void *ud, void *ptr, size_t osize, size_t nsize) {
 }
 
 
+static void exchange_lua_states(lua_State *from, lua_State *to, int level, int index) {
+    if (level >= UDATA_NESTING_LIMIT) {
+        log_critical("ctx.udata nesting limit is reached (%u)", UDATA_NESTING_LIMIT);
+        return;
+    }
+
+    /* TODO: use arrays for optimized paths */
+    /* TODO: preallocate table records */
+    switch (lua_type(from, index)) {
+    case LUA_TTABLE:
+        lua_newtable(to);
+        lua_pushnil(from); /* first key */
+        while (lua_next(from, index - 1) != 0) {
+            /* 'key' at index -2 and 'value' at index -1 */
+            exchange_lua_states(from, to, level + 1, -2);
+            exchange_lua_states(from, to, level + 1, -1);
+            lua_settable(to, index - 2);
+            /* removes 'value'; keeps 'key' for next iteration */
+            lua_pop(from, 1);
+        }
+        break;
+    case LUA_TNUMBER:
+        lua_pushnumber(to, lua_tonumber(from, index));
+        break;
+    case LUA_TBOOLEAN:
+        lua_pushboolean(to, lua_toboolean(from, index));
+        break;
+    case LUA_TSTRING:
+        lua_pushstring(to, lua_tostring(from, index));
+        break;
+    case LUA_TNIL:
+        lua_pushnil(to);
+        break;
+    default:
+        /* TODO: provide a path and type of it for better diagnostic */
+        log_warn("Unserializable udata found and is ignored");
+        break;
+    }
+}
+
+
 void game_tick(void) {
     if (ctx.initialization_needed) {
         if (!ctx.udata)
@@ -108,13 +152,29 @@ void game_tick(void) {
         State *state = ctx.udata;
 
         /* let's init lua */
-        /* state existed already */
+        lua_State *new_state = luaL_newstate();
+        lua_setallocf(new_state, custom_alloc, NULL);
+
+        /* state existed already, copy its udata over */
         if (state->L != NULL) {
+            lua_getglobal(state->L, "ctx");
+            lua_getfield(state->L, -1, "udata");
+            SDL_assert(!lua_isnoneornil(state->L, -1));
+            SDL_assert(!lua_isnoneornil(state->L, -2));
+            // SDL_TriggerBreakpoint();
+            if (!lua_isnoneornil(state->L, -1)) {
+                log_info("Exchanging lua states...");
+                lua_newtable(new_state);
+                exchange_lua_states(state->L, new_state, 0, -1);
+                lua_setfield(new_state, -2, "udata");
+                lua_setglobal(new_state, "ctx");
+            }
+
+            /* bye :) */
             lua_close(state->L);
         }
-        state->L = luaL_newstate();
 
-        lua_setallocf(state->L, custom_alloc, NULL);
+        state->L = new_state;
 
         /* fakey version of luaL_openlibs() that excludes file i/o and os stuff */
         {

apps/twnlua/minilua.h

@@ -383,7 +383,8 @@ extern "C" {
 
 #else				/* }{ */
 
-#define LUA_API		extern
+/* TWN: Don't export anything, there's no need. */
+#define LUA_API		LUAI_FUNC
 
 #endif				/* } */
 

include/twn_draw.h

@@ -66,7 +66,6 @@ TWN_API void draw_triangle(char const *texture,
                            Color       c1,      /* optional, default: all 255 */
                            Color       c2);     /* optional, default: all 255 */
 
-/* TODO: double sided option */
 TWN_API void draw_quad(char const *texture,
                        Vec3        v0,          /* upper-left */
                        Vec3        v1,          /* bottom-left */
@@ -75,11 +74,12 @@ TWN_API void draw_quad(char const *texture,
                        Rect        texture_region,
                        Color       color);      /* optional, default: all 255 */
 
-TWN_API void draw_billboard(const char *texture,
-                            Vec3 position,
-                            Vec2 size,
-                            Color color,        /* optional, default: all 255 */
-                            bool cylindrical);  /* optional, default: false */
+TWN_API void draw_billboard(char const *texture,
+                            Vec3        position,
+                            Vec2        size,
+                            Rect const *texture_region, /* optional, default: NULL */
+                            Color       color,          /* optional, default: all 255 */
+                            bool        cylindrical);   /* optional, default: false */
 
 TWN_API void draw_camera_2d(Vec2 position,      /* optional, default: (0, 0) */
                             float rotation,     /* optional, default: 0 */

share/twn_api.json

@@ -180,6 +180,7 @@
                 { "name": "texture", "type": "char *" },
                 { "name": "position", "type": "Vec3" },
                 { "name": "size", "type": "Vec2" },
+                { "name": "texture_region", "type": "Rect *", "default": {} },
                 { "name": "color", "type": "Color", "default": { "r": 255, "g": 255, "b": 255, "a": 255 } },
                 { "name": "cylindrical", "type": "bool", "default": false }
             ]

src/rendering/twn_billboards.c

@@ -9,9 +9,10 @@
 #include <stb_ds.h>
 
 
-void draw_billboard(const char *texture,
+void draw_billboard(char const *texture,
                     Vec3 position,
                     Vec2 size,
+                    Rect const *texture_region,
                     Color color,
                     bool cylindrical)
 {
@@ -30,8 +31,12 @@ void draw_billboard(const char *texture,
         .cylindrical = cylindrical,
         .position = position,
         .size = size,
+        .texture_region_opt_set = texture_region != NULL,
     };
 
+    if (texture_region)
+        billboard.texture_region_opt = *texture_region;
+
     struct SpaceBillboard *billboards = (struct SpaceBillboard *)(void *)batch_p->value.primitives;
 
     arrpush(billboards, billboard);
@@ -81,10 +86,10 @@ void finally_draw_billboard_batch(struct MeshBatch const *batch,
     const float xr = srcrect.x / dims.w;
     const float yr = srcrect.y / dims.h;
 
-    const Vec2 uv0 = { xr,           yr      };
-    const Vec2 uv1 = { xr,           yr + hr };
-    const Vec2 uv2 = { xr + wr,      yr + hr };
-    const Vec2 uv3 = { xr + wr,      yr      };
+    const Vec2 uv0c = { xr,           yr      };
+    const Vec2 uv1c = { xr,           yr + hr };
+    const Vec2 uv2c = { xr + wr,      yr + hr };
+    const Vec2 uv3c = { xr + wr,      yr      };
 
     for (size_t batch_n = 0; batch_n <= (primitives_len - 1) / QUAD_ELEMENT_BUFFER_LENGTH; batch_n++) {
 
@@ -107,6 +112,20 @@ void finally_draw_billboard_batch(struct MeshBatch const *batch,
                 b = vec3_mul(right_minus_up, ((Vec3){billboard.size.x, billboard.size.y, billboard.size.x }));
             }
 
+            Vec2 uv0, uv1, uv2, uv3;
+            if (billboard.texture_region_opt_set) {
+                uv0 = (Vec2){ (srcrect.x + billboard.texture_region_opt.x) / dims.w,
+                              (srcrect.y + billboard.texture_region_opt.y) / dims.h };
+                uv1 = (Vec2){ (srcrect.x + billboard.texture_region_opt.x) / dims.w,
+                              (srcrect.y + billboard.texture_region_opt.y  + billboard.texture_region_opt.h) / dims.h };
+                uv2 = (Vec2){ (srcrect.x + billboard.texture_region_opt.x  + billboard.texture_region_opt.w) / dims.w,
+                              (srcrect.y + billboard.texture_region_opt.y  + billboard.texture_region_opt.h) / dims.h };
+                uv3 = (Vec2){ (srcrect.x + billboard.texture_region_opt.x  + billboard.texture_region_opt.w) / dims.w,
+                              (srcrect.y + billboard.texture_region_opt.y) / dims.h };
+            } else {
+                uv0 = uv0c; uv1 = uv1c; uv2 = uv2c; uv3 = uv3c;
+            }
+
             struct ElementIndexedBillboard const payload = {
                 /* flat shading is assumed, so we can skip setting the duplicates */
                 .c0 = billboard.color,

src/rendering/twn_draw_c.h

@@ -121,6 +121,8 @@ typedef struct SpaceBillboard {
     Vec3 position;
     Vec2 size;
     Color color;
+    m_option_list(
+        Rect, texture_region )
     // TextureKey texture; /* is assumed from other places */
     bool cylindrical;
 } SpaceBillboard;