From e4629eb9ef1f1b22d42f03852bb914461e0b6e02 Mon Sep 17 00:00:00 2001
From: Dan Paulat <dpaulat@gmail.com>
Date: Wed, 5 Oct 2022 23:10:23 -0500
Subject: [PATCH] Expose texture attributes in interface

---
 scwx-qt/source/scwx/qt/util/texture_atlas.cpp | 54 +++++++++++++------
 scwx-qt/source/scwx/qt/util/texture_atlas.hpp | 42 +++++++++++++++
 2 files changed, 80 insertions(+), 16 deletions(-)

diff --git a/scwx-qt/source/scwx/qt/util/texture_atlas.cpp b/scwx-qt/source/scwx/qt/util/texture_atlas.cpp
index 6047550e..7ff156f4 100644
--- a/scwx-qt/source/scwx/qt/util/texture_atlas.cpp
+++ b/scwx-qt/source/scwx/qt/util/texture_atlas.cpp
@@ -23,17 +23,6 @@ namespace util
 static const std::string logPrefix_ = "scwx::qt::util::texture_atlas";
 static const auto        logger_    = scwx::util::Logger::Create(logPrefix_);
 
-struct TextureInfo
-{
-   TextureInfo(boost::gil::point_t position, boost::gil::point_t size) :
-       position_ {position}, size_ {size}
-   {
-   }
-
-   boost::gil::point_t position_;
-   boost::gil::point_t size_;
-};
-
 class TextureAtlas::Impl
 {
 public:
@@ -52,9 +41,9 @@ public:
    std::unordered_map<std::string, std::string> texturePathMap_;
    std::shared_mutex                            texturePathMutex_;
 
-   boost::gil::rgba8_image_t                    atlas_;
-   std::unordered_map<std::string, TextureInfo> atlasMap_;
-   std::shared_mutex                            atlasMutex_;
+   boost::gil::rgba8_image_t                          atlas_;
+   std::unordered_map<std::string, TextureAttributes> atlasMap_;
+   std::shared_mutex                                  atlasMutex_;
 };
 
 TextureAtlas::TextureAtlas() : p(std::make_unique<Impl>()) {}
@@ -146,6 +135,11 @@ void TextureAtlas::BuildAtlas(size_t width, size_t height)
    // Populate atlas
    logger_->trace("Populating atlas");
 
+   const float xStep = 1.0f / width;
+   const float yStep = 1.0f / height;
+   const float xMin  = xStep * 0.5f;
+   const float yMin  = yStep * 0.5f;
+
    for (size_t i = 0; i < images.size(); i++)
    {
       // If the image was packed successfully
@@ -164,12 +158,26 @@ void TextureAtlas::BuildAtlas(size_t width, size_t height)
          boost::gil::copy_pixels(imageView, atlasSubView);
 
          // Add texture image to the index
+         const stbrp_coord x = stbrpRects[i].x;
+         const stbrp_coord y = stbrpRects[i].y;
+
+         const float sLeft = x * xStep + xMin;
+         const float sRight =
+            sLeft + static_cast<float>(imageView.width() - 1) / width;
+         const float tTop = y * yStep + yMin;
+         const float tBottom =
+            tTop + static_cast<float>(imageView.height() - 1) / height;
+
          p->atlasMap_.emplace(
             std::piecewise_construct,
             std::forward_as_tuple(images[i].first),
             std::forward_as_tuple(
-               boost::gil::point_t {stbrpRects[i].x, stbrpRects[i].y},
-               boost::gil::point_t {imageView.width(), imageView.height()}));
+               boost::gil::point_t {x, y},
+               boost::gil::point_t {imageView.width(), imageView.height()},
+               sLeft,
+               sRight,
+               tTop,
+               tBottom));
       }
       else
       {
@@ -222,6 +230,20 @@ GLuint TextureAtlas::BufferAtlas(gl::OpenGLFunctions& gl)
    return texture;
 }
 
+TextureAttributes TextureAtlas::GetTextureAttributes(const std::string& name)
+{
+   TextureAttributes attr {};
+   std::shared_lock  lock(p->atlasMutex_);
+
+   const auto& it = p->atlasMap_.find(name);
+   if (it != p->atlasMap_.cend())
+   {
+      attr = it->second;
+   }
+
+   return attr;
+}
+
 boost::gil::rgba8_image_t
 TextureAtlas::Impl::LoadImage(const std::string& imagePath)
 {
diff --git a/scwx-qt/source/scwx/qt/util/texture_atlas.hpp b/scwx-qt/source/scwx/qt/util/texture_atlas.hpp
index b442f540..bf904e6c 100644
--- a/scwx-qt/source/scwx/qt/util/texture_atlas.hpp
+++ b/scwx-qt/source/scwx/qt/util/texture_atlas.hpp
@@ -5,6 +5,8 @@
 #include <memory>
 #include <string>
 
+#include <boost/gil/point.hpp>
+
 namespace scwx
 {
 namespace qt
@@ -12,6 +14,44 @@ namespace qt
 namespace util
 {
 
+struct TextureAttributes
+{
+   TextureAttributes() :
+       valid_ {false},
+       position_ {},
+       size_ {},
+       sLeft_ {},
+       sRight_ {},
+       tTop_ {},
+       tBottom_ {}
+   {
+   }
+
+   TextureAttributes(boost::gil::point_t position,
+                     boost::gil::point_t size,
+                     float               sLeft,
+                     float               sRight,
+                     float               tTop,
+                     float               tBottom) :
+       valid_ {true},
+       position_ {position},
+       size_ {size},
+       sLeft_ {sLeft},
+       sRight_ {sRight},
+       tTop_ {tTop},
+       tBottom_ {tBottom}
+   {
+   }
+
+   bool                valid_;
+   boost::gil::point_t position_;
+   boost::gil::point_t size_;
+   float               sLeft_;
+   float               sRight_;
+   float               tTop_;
+   float               tBottom_;
+};
+
 class TextureAtlas
 {
 public:
@@ -30,6 +70,8 @@ public:
    void   BuildAtlas(size_t width, size_t height);
    GLuint BufferAtlas(gl::OpenGLFunctions& gl);
 
+   TextureAttributes GetTextureAttributes(const std::string& name);
+
 private:
    class Impl;