From ab50f0b9a2f0f266dc3dd051602b5c0c3a7eae35 Mon Sep 17 00:00:00 2001
From: Dan Paulat <dpaulat@gmail.com>
Date: Tue, 4 Oct 2022 23:15:52 -0500
Subject: [PATCH] Add texture loading in GlContext

---
 scwx-qt/source/scwx/qt/gl/gl_context.cpp | 120 ++++++++++++++++++++++-
 scwx-qt/source/scwx/qt/gl/gl_context.hpp |   2 +
 2 files changed, 120 insertions(+), 2 deletions(-)

diff --git a/scwx-qt/source/scwx/qt/gl/gl_context.cpp b/scwx-qt/source/scwx/qt/gl/gl_context.cpp
index 3db875a8..8384a8ef 100644
--- a/scwx-qt/source/scwx/qt/gl/gl_context.cpp
+++ b/scwx-qt/source/scwx/qt/gl/gl_context.cpp
@@ -1,5 +1,14 @@
 #include <scwx/qt/gl/gl_context.hpp>
+#include <scwx/qt/util/streams.hpp>
 #include <scwx/util/hash.hpp>
+#include <scwx/util/logger.hpp>
+
+#pragma warning(push, 0)
+#include <boost/gil.hpp>
+#include <boost/gil/extension/io/png.hpp>
+#include <boost/iostreams/stream.hpp>
+#include <QFile>
+#pragma warning(pop)
 
 namespace scwx
 {
@@ -8,19 +17,34 @@ namespace qt
 namespace gl
 {
 
+static const std::string logPrefix_ = "scwx::qt::gl::gl_context";
+static const auto        logger_    = scwx::util::Logger::Create(logPrefix_);
+
 class GlContext::Impl
 {
 public:
-   explicit Impl() : gl_ {}, shaderProgramMap_ {}, shaderProgramMutex_ {} {}
+   explicit Impl() :
+       gl_ {},
+       shaderProgramMap_ {},
+       shaderProgramMutex_ {},
+       textureMap_ {},
+       textureMutex_ {}
+   {
+   }
    ~Impl() {}
 
+   GLuint CreateTexture(const std::string& texturePath);
+
    gl::OpenGLFunctions gl_;
 
    std::unordered_map<std::pair<std::string, std::string>,
                       std::shared_ptr<gl::ShaderProgram>,
-                      util::hash<std::pair<std::string, std::string>>>
+                      scwx::util::hash<std::pair<std::string, std::string>>>
               shaderProgramMap_;
    std::mutex shaderProgramMutex_;
+
+   std::unordered_map<std::string, GLuint> textureMap_;
+   std::mutex                              textureMutex_;
 };
 
 GlContext::GlContext() : p(std::make_unique<Impl>()) {}
@@ -59,6 +83,98 @@ GlContext::GetShaderProgram(const std::string& vertexPath,
    return shaderProgram;
 }
 
+GLuint GlContext::GetTexture(const std::string& texturePath)
+{
+   GLuint texture = GL_INVALID_INDEX;
+
+   std::unique_lock lock(p->textureMutex_);
+
+   auto it = p->textureMap_.find(texturePath);
+
+   if (it == p->textureMap_.end())
+   {
+      texture                     = p->CreateTexture(texturePath);
+      p->textureMap_[texturePath] = texture;
+   }
+   else
+   {
+      texture = it->second;
+   }
+
+   return texture;
+}
+
+// TODO: Move to dedicated file
+GLuint GlContext::Impl::CreateTexture(const std::string& texturePath)
+{
+   logger_->warn("Create Texture: {}", texturePath);
+
+   GLuint texture;
+
+   QFile textureFile(texturePath.c_str());
+
+   textureFile.open(QIODevice::ReadOnly);
+
+   if (!textureFile.isOpen())
+   {
+      logger_->error("Could not load texture: {}", texturePath);
+      return GL_INVALID_INDEX;
+   }
+
+   boost::iostreams::stream<util::IoDeviceSource> dataStream(textureFile);
+
+   boost::gil::rgba8_image_t image;
+
+   try
+   {
+      boost::gil::read_and_convert_image(
+         dataStream, image, boost::gil::png_tag());
+   }
+   catch (const std::exception& ex)
+   {
+      logger_->error("Error reading texture: {}", ex.what());
+      return GL_INVALID_INDEX;
+   }
+
+   boost::gil::rgba8_view_t view = boost::gil::view(image);
+
+   std::vector<boost::gil::rgba8_pixel_t> pixelData(view.width() *
+                                                    view.height());
+
+   boost::gil::copy_pixels(
+      view,
+      boost::gil::interleaved_view(view.width(),
+                                   view.height(),
+                                   pixelData.data(),
+                                   view.width() *
+                                      sizeof(boost::gil::rgba8_pixel_t)));
+
+   OpenGLFunctions& gl = gl_;
+
+   gl.glGenTextures(1, &texture);
+   gl.glBindTexture(GL_TEXTURE_2D, texture);
+
+   // TODO: Change to GL_REPEAT once a texture atlas is used
+   gl.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+   gl.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+   gl.glTexParameteri(
+      GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
+   gl.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+   gl.glTexImage2D(GL_TEXTURE_2D,
+                   0,
+                   GL_RGBA,
+                   view.width(),
+                   view.height(),
+                   0,
+                   GL_RGBA,
+                   GL_UNSIGNED_BYTE,
+                   pixelData.data());
+   gl.glGenerateMipmap(GL_TEXTURE_2D);
+
+   return texture;
+}
+
 } // namespace gl
 } // namespace qt
 } // namespace scwx
diff --git a/scwx-qt/source/scwx/qt/gl/gl_context.hpp b/scwx-qt/source/scwx/qt/gl/gl_context.hpp
index cf81262f..d1fb6645 100644
--- a/scwx-qt/source/scwx/qt/gl/gl_context.hpp
+++ b/scwx-qt/source/scwx/qt/gl/gl_context.hpp
@@ -28,6 +28,8 @@ public:
    GetShaderProgram(const std::string& vertexPath,
                     const std::string& fragmentPath);
 
+   GLuint GetTexture(const std::string& texturePath);
+
 private:
    class Impl;