Fixed premultiplied alpha. Added circle example.

AGulev · May 5, 2020 · c991a44 · c991a44
1 parent cdbaf80
commit c991a44
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Showing 9 changed files with 135 additions and 46 deletions.
diff --git a/README.md b/README.md
@@ -23,6 +23,7 @@ First of all you need to create a table with a buffer information that contain n
 `width` - buffer width, same as your texture width<br />
 `height` - buffer height, same as your texture height<br />
 `channels` - 3 for rgb, 4 for rgba<br />
+`premultiply_alpha` - alpha value will be premultiplied into the RGB color values. Optional parameter. Default is false.<br />
 
 For example:
 ```lua
@@ -35,7 +36,8 @@ local buffer_info = {
     }}),
     width = 1024,
     height = 2048,
-    channels = 4
+    channels = 4,
+    premultiply_alpha = true
   }
 ```
 Then when you have a buffer info, you can use next methods:

diff --git a/drawpixels/src/drawpixels.cpp b/drawpixels/src/drawpixels.cpp
@@ -19,6 +19,7 @@ struct BufferInfo
   int width;
   int height;
   int channels;
+  bool premultiply_alpha;
   uint8_t *bytes;
   uint32_t src_size;
 };
@@ -131,19 +132,13 @@ static void record_mix_pixel(int i, float r, float g, float b, float a)
   recordtobuffer(i + 3, oa);
 }
 
-// static void record_empty_mix_pixel(int i, float r, float g, float b, float a)
-// {
-//   float ba = 0;
-//   a = a / 255.0;
-//   float oa = a + ba * (1 - a);
-//   r = getmixrgb(1, ba, r / 255.0, a, oa);
-//   g = getmixrgb(1, ba, g / 255.0, a, oa);
-//   b = getmixrgb(1, ba, b / 255.0, a, oa);
-//   recordtobuffer(i, r);
-//   recordtobuffer(i + 1, g);
-//   recordtobuffer(i + 2, b);
-//   recordtobuffer(i + 3, oa);
-// }
+static void record_premul_alpha_pixel(int i, unsigned short r, unsigned short g, unsigned short b, unsigned short a)
+{
+  buffer_info.bytes[i] = r * a >> 8;
+  buffer_info.bytes[i + 1] = g * a >> 8;
+  buffer_info.bytes[i + 2] = b * a >> 8;
+  buffer_info.bytes[i + 3] = a;
+}
 
 static void add_point(int x, int y)
 {
@@ -181,7 +176,7 @@ static void mixpixel(int x, int y, float r, float g, float b, float a)
   }
 
   int i = xytoi(x, y);
-  if (buffer_info.channels == 3 || buffer_info.bytes[i + 3] == 0 || a == 255)
+  if (buffer_info.channels == 3 || a == 255 || (!buffer_info.premultiply_alpha && buffer_info.bytes[i + 3] == 0))
   {
     record_pixel(i, r, g, b, a);
     return;
@@ -190,10 +185,10 @@ static void mixpixel(int x, int y, float r, float g, float b, float a)
   {
     return;
   }
-  // if (buffer_info.bytes[i + 3] == 0)
-  // {
-  //   record_empty_mix_pixel(i, r, g, b, a);
-  // }
+  if (buffer_info.premultiply_alpha && buffer_info.bytes[i + 3] == 0)
+  {
+    record_premul_alpha_pixel(i, r, g, b, a);
+  }
 
   record_mix_pixel(i, r, g, b, a);
 }
@@ -559,7 +554,8 @@ static void read_and_validate_buffer_info(lua_State *L, int index)
   lua_getfield(L, index, "width");
   lua_getfield(L, index, "height");
   lua_getfield(L, index, "channels");
-  dmScript::LuaHBuffer *lua_buffer = dmScript::CheckBuffer(L, -4);
+  lua_getfield(L, index, "premultiply_alpha");
+  dmScript::LuaHBuffer *lua_buffer = dmScript::CheckBuffer(L, -5);
   buffer_info.buffer = lua_buffer->m_Buffer;
 
   if (!dmBuffer::IsBufferValid(buffer_info.buffer))
@@ -573,23 +569,32 @@ static void read_and_validate_buffer_info(lua_State *L, int index)
     luaL_error(L, "Buffer is invalid");
   }
 
-  buffer_info.width = lua_tointeger(L, -3);
+  buffer_info.width = lua_tointeger(L, -4);
   if (buffer_info.width == 0)
   {
     luaL_error(L, "'width' of the buffer should be an integer and > 0");
   }
 
-  buffer_info.height = lua_tointeger(L, -2);
+  buffer_info.height = lua_tointeger(L, -3);
   if (buffer_info.height == 0)
   {
     luaL_error(L, "'height' of the buffer should be an integer and > 0");
   }
 
-  buffer_info.channels = lua_tointeger(L, -1);
+  buffer_info.channels = lua_tointeger(L, -2);
   if (buffer_info.channels == 0)
   {
     luaL_error(L, "'channels' of should be an integer and 3 or 4");
   }
+
+  if (lua_isboolean(L, -1) == 1)
+  {
+    buffer_info.premultiply_alpha = lua_toboolean(L, -1);
+  }
+  else
+  {
+    buffer_info.premultiply_alpha = false;
+  }
 }
 
 static void draw_line(int x0, int y0, int x1, int y1, int r, int g, int b, int a)
@@ -1300,7 +1305,7 @@ static int stop_record_points_lua(lua_State *L)
 
 static int fill_area_lua(lua_State *L)
 {
-  int top = lua_gettop(L) + 4;
+  int top = lua_gettop(L) + 5;
   read_and_validate_buffer_info(L, 1);
   int32_t x = luaL_checknumber(L, 2);
   int32_t y = luaL_checknumber(L, 3);
@@ -1326,7 +1331,7 @@ static int fill_area_lua(lua_State *L)
 
 static int draw_triangle_lua(lua_State *L)
 {
-  int top = lua_gettop(L) + 4;
+  int top = lua_gettop(L) + 5;
 
   read_and_validate_buffer_info(L, 1);
   int32_t x0 = luaL_checknumber(L, 2);
@@ -1355,7 +1360,7 @@ static int draw_triangle_lua(lua_State *L)
 
 static int draw_line_lua(lua_State *L)
 {
-  int top = lua_gettop(L) + 4;
+  int top = lua_gettop(L) + 5;
 
   read_and_validate_buffer_info(L, 1);
   int32_t x0 = luaL_checknumber(L, 2);
@@ -1400,7 +1405,7 @@ static int draw_line_lua(lua_State *L)
 
 static int draw_gradient_line_lua(lua_State *L)
 {
-  int top = lua_gettop(L) + 4;
+  int top = lua_gettop(L) + 5;
 
   read_and_validate_buffer_info(L, 1);
   int32_t x0 = luaL_checknumber(L, 2);
@@ -1457,7 +1462,7 @@ static int draw_gradient_line_lua(lua_State *L)
 
 static int draw_arc_lua(lua_State *L)
 {
-  int top = lua_gettop(L) + 4;
+  int top = lua_gettop(L) + 5;
 
   read_and_validate_buffer_info(L, 1);
   int32_t posx = luaL_checknumber(L, 2);
@@ -1483,7 +1488,7 @@ static int draw_arc_lua(lua_State *L)
 
 static int draw_filled_arc_lua(lua_State *L)
 {
-  int top = lua_gettop(L) + 4;
+  int top = lua_gettop(L) + 5;
 
   read_and_validate_buffer_info(L, 1);
   int32_t posx = luaL_checknumber(L, 2);
@@ -1516,7 +1521,7 @@ static int draw_filled_arc_lua(lua_State *L)
 
 static int draw_gradient_arc_lua(lua_State *L)
 {
-  int top = lua_gettop(L) + 4;
+  int top = lua_gettop(L) + 5;
 
   read_and_validate_buffer_info(L, 1);
   int32_t posx = luaL_checknumber(L, 2);
@@ -1565,7 +1570,7 @@ static int draw_gradient_arc_lua(lua_State *L)
 
 static int draw_circle_lua(lua_State *L)
 {
-  int top = lua_gettop(L) + 4;
+  int top = lua_gettop(L) + 5;
 
   read_and_validate_buffer_info(L, 1);
   int32_t posx = luaL_checknumber(L, 2);
@@ -1609,7 +1614,7 @@ static int draw_circle_lua(lua_State *L)
 
 static int draw_filled_circle_lua(lua_State *L)
 {
-  int top = lua_gettop(L) + 4;
+  int top = lua_gettop(L) + 5;
 
   read_and_validate_buffer_info(L, 1);
   int32_t posx = luaL_checknumber(L, 2);
@@ -1644,7 +1649,7 @@ static int draw_filled_circle_lua(lua_State *L)
 
 static int fill_texture_lua(lua_State *L)
 {
-  int top = lua_gettop(L) + 4;
+  int top = lua_gettop(L) + 5;
 
   read_and_validate_buffer_info(L, 1);
   uint8_t r = luaL_checknumber(L, 2);
@@ -1678,7 +1683,7 @@ static int fill_texture_lua(lua_State *L)
 
 static int draw_rect_lua(lua_State *L)
 {
-  int top = lua_gettop(L) + 4;
+  int top = lua_gettop(L) + 5;
 
   read_and_validate_buffer_info(L, 1);
   int32_t posx = luaL_checknumber(L, 2);
@@ -1729,7 +1734,7 @@ bool sort_coords(const Point &p1, const Point &p2)
 
 static int draw_filled_rect_lua(lua_State *L)
 {
-  int top = lua_gettop(L) + 4;
+  int top = lua_gettop(L) + 5;
 
   read_and_validate_buffer_info(L, 1);
   int32_t posx = luaL_checknumber(L, 2);
@@ -1792,7 +1797,7 @@ static int draw_filled_rect_lua(lua_State *L)
 
 static int draw_pixel_lua(lua_State *L)
 {
-  int top = lua_gettop(L) + 4;
+  int top = lua_gettop(L) + 5;
 
   read_and_validate_buffer_info(L, 1);
   int32_t x = luaL_checknumber(L, 2);
@@ -1814,7 +1819,7 @@ static int draw_pixel_lua(lua_State *L)
 
 static int read_color_lua(lua_State *L)
 {
-  int top = lua_gettop(L) + 4;
+  int top = lua_gettop(L) + 5;
 
   read_and_validate_buffer_info(L, 1);
   int32_t x = luaL_checknumber(L, 2);
@@ -1840,7 +1845,7 @@ static int read_color_lua(lua_State *L)
 
 static int draw_bezier_lua(lua_State *L)
 {
-  int top = lua_gettop(L) + 4;
+  int top = lua_gettop(L) + 5;
 
   read_and_validate_buffer_info(L, 1);
   int32_t x0 = luaL_checknumber(L, 2);

diff --git a/examples/arcs/arcs.collection b/examples/arcs/arcs.collection
@@ -22,7 +22,7 @@ embedded_instances {
   "  type: \"sprite\"\n"
   "  data: \"tile_set: \\\"/examples/full.atlas\\\"\\n"
   "default_animation: \\\"fullscreen512\\\"\\n"
-  "material: \\\"/examples/sprite.material\\\"\\n"
+  "material: \\\"/builtins/materials/sprite.material\\\"\\n"
   "blend_mode: BLEND_MODE_ALPHA\\n"
   "\"\n"
   "  position {\n"

diff --git a/examples/circle/circle.collection b/examples/circle/circle.collection
@@ -0,0 +1,57 @@
+name: "default"
+scale_along_z: 0
+embedded_instances {
+  id: "canvas"
+  data: "components {\n"
+  "  id: \"circle\"\n"
+  "  component: \"/examples/circle/circle.script\"\n"
+  "  position {\n"
+  "    x: 0.0\n"
+  "    y: 0.0\n"
+  "    z: 0.0\n"
+  "  }\n"
+  "  rotation {\n"
+  "    x: 0.0\n"
+  "    y: 0.0\n"
+  "    z: 0.0\n"
+  "    w: 1.0\n"
+  "  }\n"
+  "}\n"
+  "embedded_components {\n"
+  "  id: \"sprite\"\n"
+  "  type: \"sprite\"\n"
+  "  data: \"tile_set: \\\"/examples/full.atlas\\\"\\n"
+  "default_animation: \\\"fullscreen512\\\"\\n"
+  "material: \\\"/examples/sprite.material\\\"\\n"
+  "blend_mode: BLEND_MODE_ALPHA\\n"
+  "\"\n"
+  "  position {\n"
+  "    x: 8.572\n"
+  "    y: 0.0\n"
+  "    z: 0.0\n"
+  "  }\n"
+  "  rotation {\n"
+  "    x: 0.0\n"
+  "    y: 0.0\n"
+  "    z: 0.0\n"
+  "    w: 1.0\n"
+  "  }\n"
+  "}\n"
+  ""
+  position {
+    x: 248.0
+    y: 500.0
+    z: 0.0
+  }
+  rotation {
+    x: 0.0
+    y: 0.0
+    z: 0.0
+    w: 1.0
+  }
+  scale3 {
+    x: 1.0
+    y: 1.0
+    z: 1.0
+  }
+}
diff --git a/examples/circle/circle.script b/examples/circle/circle.script
@@ -0,0 +1,24 @@
+function init(self)
+  msg.post("@render:", "clear_color", {color = vmath.vector4(1, 0, 0, 1)})
+  -- size of texture when scaled to nearest power of two
+  local width = 64
+  local height = 64
+  local channels = 4
+
+  self.resource_path = go.get("#sprite", "texture0")
+
+  self.buffer_info = {
+    buffer = buffer.create(width * height, {{name = hash("rgba"), type = buffer.VALUE_TYPE_UINT8, count = channels}}),
+    width = width,
+    height = height,
+    channels = channels,
+    premultiply_alpha = true
+  }
+
+  self.header = {width = width, height = height, type = resource.TEXTURE_TYPE_2D, format = resource.TEXTURE_FORMAT_RGBA, num_mip_maps = 1}
+  drawpixels.fill(self.buffer_info, 0, 0, 0, 0)
+
+  drawpixels.circle(self.buffer_info, width * 0.5, width * 0.5, width * 0.9, 0, 0, 255, 255, true)
+
+  resource.set_texture(self.resource_path, self.header, self.buffer_info.buffer)
+end
diff --git a/examples/fills/fills.collection b/examples/fills/fills.collection
@@ -22,7 +22,7 @@ embedded_instances {
   "  type: \"sprite\"\n"
   "  data: \"tile_set: \\\"/examples/full.atlas\\\"\\n"
   "default_animation: \\\"fullscreen512\\\"\\n"
-  "material: \\\"/examples/sprite.material\\\"\\n"
+  "material: \\\"/builtins/materials/sprite.material\\\"\\n"
   "blend_mode: BLEND_MODE_ALPHA\\n"
   "\"\n"
   "  position {\n"

diff --git a/examples/lines_aa/lines.script b/examples/lines_aa/lines.script
@@ -1,5 +1,5 @@
 function init(self)
-  msg.post("@render:", "clear_color", {color = vmath.vector4(1, 1, 1, 1)})
+  msg.post("@render:", "clear_color", {color = vmath.vector4(1, 1, 0, 1)})
   -- size of texture when scaled to nearest power of two
   local width = 512
   local height = 512
@@ -11,11 +11,12 @@ function init(self)
     buffer = buffer.create(width * height, {{name = hash("rgba"), type = buffer.VALUE_TYPE_UINT8, count = channels}}),
     width = width,
     height = height,
-    channels = channels
+    channels = channels,
+    premultiply_alpha = true
   }
 
   self.header = {width = width, height = height, type = resource.TEXTURE_TYPE_2D, format = resource.TEXTURE_FORMAT_RGBA, num_mip_maps = 1}
-  drawpixels.fill(self.buffer_info, 255, 255, 0, 255)
+  drawpixels.fill(self.buffer_info, 0, 0, 0, 0)
 
   drawpixels.gradient_line(self.buffer_info, width * 0.2, width * 0.1, width * 0.9, width * 0.9, 255, 0, 0, 0, 0, 255, 255, true, 12)
   drawpixels.line(self.buffer_info, width * 0.2, width * 0.5, width * 0.9, width * 0.9, 0, 0, 255, 255, true, 5)

diff --git a/examples/lines_aa/lines_aa.collection b/examples/lines_aa/lines_aa.collection
@@ -22,7 +22,7 @@ embedded_instances {
   "  type: \"sprite\"\n"
   "  data: \"tile_set: \\\"/examples/full.atlas\\\"\\n"
   "default_animation: \\\"fullscreen512\\\"\\n"
-  "material: \\\"/examples/sprite.material\\\"\\n"
+  "material: \\\"/builtins/materials/sprite.material\\\"\\n"
   "blend_mode: BLEND_MODE_ALPHA\\n"
   "\"\n"
   "  position {\n"

diff --git a/examples/sprite.material b/examples/sprite.material
@@ -27,6 +27,6 @@ samplers {
   name: "texture_sampler"
   wrap_u: WRAP_MODE_CLAMP_TO_EDGE
   wrap_v: WRAP_MODE_CLAMP_TO_EDGE
-  filter_min: FILTER_MODE_MIN_LINEAR
-  filter_mag: FILTER_MODE_MAG_LINEAR
+  filter_min: FILTER_MODE_MIN_NEAREST
+  filter_mag: FILTER_MODE_MAG_NEAREST
 }