Added more functions

example.lua

@@ -4,17 +4,19 @@
 
 function tick(t)
     --           Background
-    Draw.clear(math.floor(t * 255))
+    Draw.clear(0xFF131300 | math.floor(128 + math.sin(t) * 127))
 
---[[
     --         Color ARGB,  x,  y
-    Draw.pixel(0xFFFF0000, 30, 30)
+    Draw.pixel(0xFFFF0000,
+      (math.sin(t) * 0.5 + 0.5) * 1920,
+      (math.cos(t) * 0.5 + 0.5) * 1080)
 
     --        Color ARGB, thickness,  x1,  y1,  x2,  y2,  xn,  yn, ...
     Draw.line(0xFFFF00FF,         8, 100, 100, 200, 400, 300, 600) --> { Vec2, ... }
-    --        Color ARGB, thickness,  x1,  y1,  x2,  y2,  xn,  yn, ...
+    --        Color ARGB,  x1,  y1,  x2,  y2,  xn,  yn, ...
-    Draw.poly(0xFFFF00FF,         8, 100, 100, 200, 400, 300, 600) --> Rect
+    Draw.poly(0xFFFF00FF, 100, 100, 200, 400, 150, 500) --> Rect
 
+    --[[
     --          Color ARGB, radius,   x,   y, start, end
     Draw.circle(0xFFFF0000,     20, 300, 300) --> Rect
     --        Color ARGB, outer, inner,  x,   y, start, end

src/api_draw.c

@@ -5,10 +5,16 @@
 #include <lua5.3/lauxlib.h>
 
 int api_draw_clear(lua_State *L);
+int api_draw_pixel(lua_State *L);
+int api_draw_line(lua_State *L);
+int api_draw_poly(lua_State *L);
 
 bool loadapi_draw(lua_State *lua) {
   const struct luaL_Reg api_draw[] = {
     { "clear", api_draw_clear },
+    { "pixel", api_draw_pixel },
+    { "line", api_draw_line },
+    { "poly", api_draw_poly },
   };
   lua_newtable(lua);
   luaL_setfuncs(lua, api_draw, 0);
@@ -16,15 +22,88 @@ bool loadapi_draw(lua_State *lua) {
   return true;
 }
 
+void argb_to_cairo(int color, double *a, double *r, double *g, double *b) {
+  int ia = (color >> 24) & 0xFF,
+      ir = (color >> 16) & 0xFF,
+      ig = (color >> 8) & 0xFF,
+      ib = color & 0xFF;
+  *r = ir / 255.0;
+  *g = ig / 255.0;
+  *b = ib / 255.0;
+  *a = ia / 255.0;
+}
+
 int api_draw_clear(lua_State *L) {
-  printf("Draw.clear()\n");
-  int color = luaL_checkinteger(L, 1);
-  printf("Draw.clear(0x%08x)\n", color);
   cairo_t *cr = global_context.cairo_context.cairo;
-  int r = (color >> 16) & 0xFF,
+  int color = luaL_checkinteger(L, 1);
-      g = (color >> 8) & 0xFF,
+  double a, r, g, b;
-      b = color & 0xFF;
+  argb_to_cairo(color, &a, &r, &g, &b);
-  cairo_set_source_rgb(cr, r / 255.0, g / 255.0, b / 255.0);
+  cairo_set_source_rgba(cr, r, g, b, a);
   cairo_paint(cr);
   return 0;
 }
+
+int api_draw_pixel(lua_State *L) {
+  cairo_t *cr = global_context.cairo_context.cairo;
+  int color = luaL_checkinteger(L, 1);
+  lua_Number x = luaL_checknumber(L, 2);
+  lua_Number y = luaL_checknumber(L, 3);
+  double a, r, g, b;
+  argb_to_cairo(color, &a, &r, &g, &b);
+  cairo_set_source_rgba(cr, r, g, b, a);
+  cairo_rectangle(cr, x, y, 1, 1);
+  cairo_fill(cr);
+  return 0;
+}
+
+int api_draw_line(lua_State *L) {
+  cairo_t *cr = global_context.cairo_context.cairo;
+
+  if (lua_gettop(L) < 6) {
+    return luaL_error(L, "Not enough arguments: should have at least 2 points");
+  }
+
+  int color = luaL_checkinteger(L, 1);
+  double a, r, g, b;
+  argb_to_cairo(color, &a, &r, &g, &b);
+
+  lua_Number width = luaL_checknumber(L, 2);
+  lua_Number x = luaL_checknumber(L, 3);
+  lua_Number y = luaL_checknumber(L, 4);
+
+  cairo_set_source_rgba(cr, r, g, b, a);
+  cairo_set_line_width(cr, width);
+  cairo_move_to(cr, x, y);
+  for (int i = 5; i <= lua_gettop(L); i += 2) {
+    x = luaL_checknumber(L, i);
+    y = luaL_checknumber(L, i + 1);
+    cairo_line_to(cr, x, y);
+  }
+  cairo_stroke(cr);
+  return 0;
+}
+
+int api_draw_poly(lua_State *L) {
+  cairo_t *cr = global_context.cairo_context.cairo;
+
+  if (lua_gettop(L) < 7) {
+    return luaL_error(L, "Not enough arguments: should have at least 3 points");
+  }
+
+  int color = luaL_checkinteger(L, 1);
+  double a, r, g, b;
+  argb_to_cairo(color, &a, &r, &g, &b);
+
+  lua_Number x = luaL_checknumber(L, 2);
+  lua_Number y = luaL_checknumber(L, 3);
+
+  cairo_set_source_rgba(cr, r, g, b, a);
+  cairo_move_to(cr, x, y);
+  for (int i = 4; i <= lua_gettop(L); i += 2) {
+    x = luaL_checknumber(L, i);
+    y = luaL_checknumber(L, i + 1);
+    cairo_line_to(cr, x, y);
+  }
+  cairo_fill(cr);
+  return 0;
+}