implement heightmap grid

engine/node_image_texture.cpp

@@ -20,13 +20,14 @@ void NodeImageTexture::draw()
 {
     using namespace ui;
     tex.bind();
-    NodeImage::m_sampler.bind(0);
+    auto& sampler = tex.has_mips ? NodeImage::m_sampler : NodeImage::m_sampler_mips;
+    sampler.bind(0);
     glEnable(GL_BLEND);
     ui::ShaderManager::use(kShader::Texture);
     ui::ShaderManager::u_int(kShaderUniform::Tex, 0);
     ui::ShaderManager::u_mat4(kShaderUniform::MVP, m_mvp);
     NodeImage::m_plane.draw_fill();
-    NodeImage::m_sampler.unbind();
+    sampler.unbind();
     tex.unbind();
     glDisable(GL_BLEND);
 }