add support for high res brush textures, implement mipmaps on brush

engine/texture.h

@@ -18,6 +18,7 @@ public:
     void unbind() const { glBindTexture(GL_TEXTURE_2D, 0); }
     void update(const uint8_t* data);
     bool ready() const { return m_tex != 0; }
+    void create_mipmaps();
     glm::vec2 size() const;
 };
 
@@ -28,6 +29,7 @@ class Sampler
 public:
     bool create(GLint filter = GL_LINEAR, GLint wrap = GL_CLAMP_TO_EDGE);
     void set(GLint filter = GL_LINEAR, GLint wrap = GL_CLAMP_TO_EDGE);
+    void set_filter(GLint filter_min, GLint filter_mag);
     void bind(int unit);
     void unbind();
     bool ready() const { return id != 0; }
@@ -37,7 +39,7 @@ class TextureManager
 {
 public:
     static std::map<uint16_t, Texture2D> m_textures;
-    static bool load(const char* path);
+    static bool load(const char* path, bool generate_mipmpas = false);
     static void assign(uint16_t id, GLuint tex, int w = -1, int h = -1, GLuint internal_format = GL_RGBA8, GLuint format = GL_RGBA);
     static Texture2D& get(uint16_t id);
     static void invalidate();