Add selection rectangle. Alpha value isn't correct

src/render/Render_alternate.cpp

@@ -245,6 +245,30 @@ void  Render_alternate::paintGL(){
         //restore matrix
         _modelview = tmp;
     }
+    /*draw selection if necessary*/
+    if (_mouse_pressed && (Info::Render::_key_ctrl == false) && !_mouse_pressed_inside_container){
+        Element_pos x0, x1, y0, y1;
+        x0 = screen_to_render_x(_mouse_x);
+        y0 = /*Info::Render::height -*/ screen_to_render_y(_mouse_y);
+        x1 = screen_to_render_x(_new_mouse_x);
+        y1 = /*Info::Render::height -*/ screen_to_render_y(_new_mouse_y);
+        float selection[8] = {x0, y0, x0, y1, x1, y1, x1, y0};
+        float selection_colors[12] = {0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5};
+        /*_modelview = glm::translate(_modelview, glm::vec3(_default_entity_x_translate - _x_state_translate,
+                                                          _ruler_y + _ruler_height - _y_state_translate,
+         0));*/
+        //_modelview = glm::scale(_modelview, glm::vec3(_x_state_scale, _y_state_scale, 1));
+        glUniformMatrix4fv(glGetUniformLocation(_shader.getProgramID(), "modelview"), 1, GL_FALSE, glm::value_ptr(_modelview));
+        glUniformMatrix4fv(glGetUniformLocation(_shader.getProgramID(), "projection"), 1, GL_FALSE, glm::value_ptr(_projection));
+        glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, selection);
+        glEnableVertexAttribArray(0);
+        glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 0, selection_colors);
+        glEnableVertexAttribArray(1);
+        glDrawArrays(GL_QUADS, 0, 4);
+        glDisableVertexAttribArray(0);
+        glDisableVertexAttribArray(1);
+        _modelview = tmp;
+    }
 
     //    _containers.display(_modelview);
     //rendu
@@ -347,7 +371,10 @@ void  Render_alternate::paintGL(){
                         buf_txt.str().c_str(),
                         arial_font);
 
-    }
+        }
+
+       
+
 
 //     Render_alternate::QGLWidget::setFocus(Qt::ActiveWindowFocusReason);/* give the focus to the render area for mouse and keyboard events */