fixes #70: raster tile rendering as toggleable mode from vector

src/util/texturepool.cpp

@@ -0,0 +1,56 @@
+#include <llmr/util/texturepool.hpp>
+
+#include <vector>
+
+#define TextureMax 64
+
+using namespace llmr;
+
+GLuint Texturepool::getTextureID() {
+    if (texture_ids.empty())
+    {
+        GLuint new_texture_ids[TextureMax];
+        glGenTextures(TextureMax, new_texture_ids);
+        for (uint32_t id = 0; id < TextureMax; id++) {
+            texture_ids.insert(new_texture_ids[id]);
+        }
+    }
+
+    GLuint id = 0;
+
+    if (!texture_ids.empty()) {
+        std::set<GLuint>::iterator id_iterator = texture_ids.begin();
+        id = *id_iterator;
+        texture_ids.erase(id_iterator);
+    }
+
+    return id;
+}
+
+void Texturepool::removeTextureID(GLuint texture_id) {
+    bool needs_clear = false;
+
+    glBindTexture(GL_TEXTURE_2D, texture_id);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 0, 0, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
+
+    texture_ids.insert(texture_id);
+
+    if (texture_ids.size() > TextureMax)
+        needs_clear = true;
+
+    if (needs_clear)
+        clearTextureIDs();
+}
+
+void Texturepool::clearTextureIDs() {
+    std::vector<GLuint> ids_to_remove;
+    ids_to_remove.reserve(texture_ids.size());
+
+    for (std::set<GLuint>::iterator id_iterator = texture_ids.begin(); id_iterator != texture_ids.end(); ++id_iterator)
+        ids_to_remove.push_back(*id_iterator);
+
+    if (!ids_to_remove.empty())
+        glDeleteTextures((GLsizei)ids_to_remove.size(), &ids_to_remove[0]);
+
+    texture_ids.clear();
+}