feat: canvas from texture atlas element

src/graphics/core/Atlas.cpp

@@ -49,6 +49,14 @@ ImageData* Atlas::getImage() const {
     return image.get();
 }
 
+std::shared_ptr<Texture> Atlas::shareTexture() const {
+    return texture;
+}
+
+std::shared_ptr<ImageData> Atlas::shareImageData() const {
+    return image;
+}
+
 void AtlasBuilder::add(const std::string& name, std::unique_ptr<ImageData> image) {
     entries.push_back(atlasentry{name, std::shared_ptr<ImageData>(image.release())});
     names.insert(name);

src/graphics/core/Atlas.hpp

@@ -14,8 +14,8 @@ class ImageData;
 class Texture;
 
 class Atlas {
-    std::unique_ptr<Texture> texture;
-    std::unique_ptr<ImageData> image;
+    std::shared_ptr<Texture> texture;
+    std::shared_ptr<ImageData> image;
     std::unordered_map<std::string, UVRegion> regions;
 public:
     /// @param image atlas raster
@@ -36,6 +36,9 @@ public:
 
     Texture* getTexture() const;
     ImageData* getImage() const;
+
+    std::shared_ptr<Texture> shareTexture() const;
+    std::shared_ptr<ImageData> shareImageData() const;
 };
 
 struct atlasentry {

src/graphics/core/ImageData.cpp

@@ -95,6 +95,17 @@ void ImageData::blit(const ImageData& image, int x, int y) {
     throw std::runtime_error("mismatching format");
 }
 
+std::unique_ptr<ImageData> ImageData::cropped(int x, int y, int width, int height) const {
+    width = std::min<int>(width, this->width - x);
+    height = std::min<int>(height, this->height - y);
+    if (width <= 0 || height <= 0) {
+        throw std::runtime_error("invalid crop dimensions");
+    }
+    auto subImage = std::make_unique<ImageData>(format, width, height);
+    subImage->blitMatchingFormat(*this, -x, -y);
+    return subImage;
+}
+
 static bool clip_line(int& x1, int& y1, int& x2, int& y2, int width, int height) {
     const int left = 0;
     const int right = width;

src/graphics/core/ImageData.hpp

@@ -33,6 +33,8 @@ public:
     void extrude(int x, int y, int w, int h);
     void fixAlphaColor();
 
+    std::unique_ptr<ImageData> cropped(int x, int y, int width, int height) const;
+
     ubyte* getData() const {
         return data.get();
     }

src/graphics/core/Texture.cpp

@@ -54,6 +54,12 @@ void Texture::reload(const ubyte* data) {
     glBindTexture(GL_TEXTURE_2D, 0);
 }
 
+void Texture::reloadPartial(const ImageData& image, uint x, uint y, uint w, uint h) {
+    glBindTexture(GL_TEXTURE_2D, id);
+    glTexSubImage2D(GL_TEXTURE_2D, 0, x, y, w, h, GL_RGBA, GL_UNSIGNED_BYTE, image.getData());
+    glBindTexture(GL_TEXTURE_2D, 0);
+}
+
 std::unique_ptr<ImageData> Texture::readData() {
     auto data = std::make_unique<ubyte[]>(width * height * 4);
     glBindTexture(GL_TEXTURE_2D, id);

src/graphics/core/Texture.hpp

@@ -19,6 +19,7 @@ public:
     virtual void bind() const;
     virtual void unbind() const;
     void reload(const ubyte* data);
+    void reloadPartial(const ImageData& image, uint x, uint y, uint w, uint h);
 
     void setNearestFilter();
 

src/logic/scripting/lua/libs/libassets.cpp

@@ -7,7 +7,9 @@
 #include "engine/Engine.hpp"
 #include "graphics/commons/Model.hpp"
 #include "graphics/core/Texture.hpp"
+#include "graphics/core/Atlas.hpp"
 #include "util/Buffer.hpp"
+#include "../lua_custom_types.hpp"
 
 using namespace scripting;
 
@@ -64,8 +66,37 @@ static int l_parse_model(lua::State* L) {
     return 0;
 }
 
+static int l_to_canvas(lua::State* L) {
+    auto alias = lua::require_lstring(L, 1);
+    size_t sep = alias.rfind(':');
+    if (sep == std::string::npos) {
+        return 0;
+    }
+    auto atlasName = alias.substr(0, sep);
+    auto& assets = *engine->getAssets();
+    if (auto atlas = assets.get<Atlas>(std::string(atlasName))) {
+        auto textureName = std::string(alias.substr(sep + 1));
+        auto image = atlas->shareImageData();
+        auto texture = atlas->shareTexture();
+        if (auto region = atlas->getIf(textureName)) {
+            UVRegion uvRegion = *region;
+            int atlasWidth = static_cast<int>(image->getWidth());
+            int atlasHeight = static_cast<int>(image->getHeight());
+            int x = static_cast<int>(uvRegion.u1 * atlasWidth);
+            int y = static_cast<int>(uvRegion.v1 * atlasHeight);
+            int w = static_cast<int>(uvRegion.getWidth() * atlasWidth);
+            int h = static_cast<int>(uvRegion.getHeight() * atlasHeight);
+            return lua::newuserdata<lua::LuaCanvas>(
+                L, std::move(texture), image->cropped(x, y, w, h), uvRegion
+            );
+        }
+    }
+    return 0;
+}
+
 const luaL_Reg assetslib[] = {
     {"load_texture", lua::wrap<l_load_texture>},
     {"parse_model", lua::wrap<l_parse_model>},
+    {"to_canvas", lua::wrap<l_to_canvas>},
     {nullptr, nullptr}
 };

src/logic/scripting/lua/lua_custom_types.hpp

@@ -6,6 +6,7 @@
 #include <random>
 
 #include "lua_commons.hpp"
+#include "maths/UVRegion.hpp"
 
 struct fnl_state;
 class Heightmap;
@@ -81,8 +82,9 @@ namespace lua {
     class LuaCanvas : public Userdata {
     public:
         explicit LuaCanvas(
-            std::shared_ptr<Texture> inTexture,
-            std::shared_ptr<ImageData> inData
+            std::shared_ptr<Texture> texture,
+            std::shared_ptr<ImageData> data,
+            UVRegion region = UVRegion(0, 0, 1, 1)
         );
         ~LuaCanvas() override = default;
 
@@ -90,29 +92,32 @@ namespace lua {
             return TYPENAME;
         }
 
-        [[nodiscard]] auto& texture() const {
-            return *mTexture;
+        [[nodiscard]] auto& getTexture() const {
+            return *texture;
         }
 
-        [[nodiscard]] auto& data() const {
-            return *mData;
+        [[nodiscard]] auto& getData() const {
+            return *data;
         }
 
         [[nodiscard]] bool hasTexture() const {
-            return mTexture != nullptr;
+            return texture != nullptr;
         }
 
         auto shareTexture() const {
-            return mTexture;
+            return texture;
         }
 
+        void update();
+
         void createTexture();
 
         static int createMetatable(lua::State*);
         inline static std::string TYPENAME = "Canvas";
     private:
-        std::shared_ptr<Texture> mTexture; // nullable
-        std::shared_ptr<ImageData> mData;
+        std::shared_ptr<Texture> texture; // nullable
+        std::shared_ptr<ImageData> data;
+        UVRegion region;
     };
     static_assert(!std::is_abstract<LuaCanvas>());
 

src/logic/scripting/lua/usertypes/lua_type_canvas.cpp

@@ -10,14 +10,42 @@
 using namespace lua;
 
 LuaCanvas::LuaCanvas(
-    std::shared_ptr<Texture> inTexture, std::shared_ptr<ImageData> inData
+    std::shared_ptr<Texture> texture,
+    std::shared_ptr<ImageData> data,
+    UVRegion region
 )
-    : mTexture(std::move(inTexture)), mData(std::move(inData)) {
+    : texture(std::move(texture)),
+      data(std::move(data)),
+      region(std::move(region)) {
+}
+
+void LuaCanvas::update() {
+    if (!hasTexture()) {
+        return;
+    }
+    if (region.isFull()) {
+        texture->reload(*data);
+    } else {
+        uint texWidth = texture->getWidth();
+        uint texHeight = texture->getHeight();
+        uint imgWidth = data->getWidth();
+        uint imgHeight = data->getHeight();
+
+        uint x = static_cast<uint>(region.u1 * texWidth);
+        uint y = static_cast<uint>(region.v1 * texHeight);
+        uint w = static_cast<uint>((region.u2 - region.u1) * texWidth);
+        uint h = static_cast<uint>((region.v2 - region.v1) * texHeight);
+
+        w = std::min<uint>(w, imgWidth);
+        h = std::min<uint>(h, imgHeight);
+
+        texture->reloadPartial(*data, x, y, w, h);
+    }
 }
 
 void LuaCanvas::createTexture() {
-    mTexture = Texture::from(mData.get());
-    mTexture->setMipMapping(false, true);
+    texture = Texture::from(data.get());
+    texture->setMipMapping(false, true);
 }
 
 union RGBA {
@@ -41,7 +69,7 @@ static RGBA* get_at(const ImageData& data, uint x, uint y) {
 
 static RGBA* get_at(State* L, uint x, uint y) {
     if (auto canvas = touserdata<LuaCanvas>(L, 1)) {
-        return get_at(canvas->data(), x, y);
+        return get_at(canvas->getData(), x, y);
     }
     return nullptr;
 }
@@ -97,7 +125,7 @@ static LuaCanvas& require_canvas(State* L, int idx) {
 
 static int l_clear(State* L) {
     auto& canvas = require_canvas(L, 1);
-    auto& image = canvas.data();
+    auto& image = canvas.getData();
     ubyte* data = image.getData();
     RGBA rgba {};
     if (gettop(L) == 1) {
@@ -122,7 +150,7 @@ static int l_line(State* L) {
 
     RGBA rgba = get_rgba(L, 6);
     if (auto canvas = touserdata<LuaCanvas>(L, 1)) {
-        auto& image = canvas->data();
+        auto& image = canvas->getData();
         image.drawLine(
             x1, y1, x2, y2, glm::ivec4 {rgba.r, rgba.g, rgba.b, rgba.a}
         );
@@ -135,13 +163,13 @@ static int l_blit(State* L) {
     auto& src = require_canvas(L, 2);
     int dst_x = tointeger(L, 3);
     int dst_y = tointeger(L, 4);
-    dst.data().blit(src.data(), dst_x, dst_y);
+    dst.getData().blit(src.getData(), dst_x, dst_y);
     return 0;
 }
 
 static int l_set_data(State* L) {
     auto& canvas = require_canvas(L, 1);
-    auto& image = canvas.data();
+    auto& image = canvas.getData();
     auto data = image.getData();
 
     if (lua::isstring(L, 2)) {
@@ -166,9 +194,7 @@ static int l_set_data(State* L) {
 
 static int l_update(State* L) {
     if (auto canvas = touserdata<LuaCanvas>(L, 1)) {
-        if (canvas->hasTexture()) {
-            canvas->texture().reload(canvas->data());
-        }
+        canvas->update();
     }
     return 0;
 }
@@ -202,7 +228,7 @@ static int l_meta_index(State* L) {
     if (texture == nullptr) {
         return 0;
     }
-    auto& data = texture->data();
+    auto& data = texture->getData();
     if (isnumber(L, 2)) {
         if (auto pixel = get_at(data, static_cast<uint>(tointeger(L, 2)))) {
             return pushinteger(L, pixel->rgba);
@@ -231,7 +257,7 @@ static int l_meta_newindex(State* L) {
     if (texture == nullptr) {
         return 0;
     }
-    auto& data = texture->data();
+    auto& data = texture->getData();
     if (isnumber(L, 2) && isnumber(L, 3)) {
         if (auto pixel = get_at(data, static_cast<uint>(tointeger(L, 2)))) {
             pixel->rgba = static_cast<uint>(tointeger(L, 3));

src/maths/UVRegion.hpp

@@ -1,8 +1,7 @@
 #pragma once
 
 #include <cmath>
-#include <glm/vec2.hpp>
-#include <glm/vec4.hpp>
+#include <glm/glm.hpp>
 
 struct UVRegion {
     float u1;
@@ -69,4 +68,10 @@ struct UVRegion {
         copy.scale(scale);
         return copy;
     }
+
+    bool isFull() const {
+        const auto e = 1e-7;
+        return glm::abs(u1 - 0.0) < e && glm::abs(v1 - 0.0) < e &&
+               glm::abs(u2 - 1.0) < e && glm::abs(v2 - 1.0) < e;
+    }
 };