I want to imply a mask on the map and make the mask moving together with player. I found some articles doing this by using CCRenderTexture, but CCRenderTexture becomes slow on some old winxp computers, especially when this mask is refreshing every frame, i don’t know the reason. So i wonders if there is any way to do this job without CCRenderTexture. I tried simply change the blendfunc of ccsprite, but it only works in the area will ccsprite is, and it also dont mix together when there are two of masks. I’m not familiar with opengl es, is there any way to make a mask working like a CCClippingNode? I just want a transparent black layer masked by sprites and then being rendered to the screen, the z-order doesn’t help, but clipping nodes works like this. There is another question, if i have to use shader, does the shader works depend on graphic card, i mean if the graphic card is old, will it draw down the frame rate?
Thanks in advance 
