First, a picture to show my question:
As you can see in the second picture, when I scale two vertices of a quad the texture gets distorted wrong. Because a quad is basically two triangles, when I distort the quad only one triangle is being stretched, so the texture warps badly revealing the hidden edge.
I want to map the texture as in the 3rd image (I've done that subdividing the quad multiple times). Is there any option to map the texture so I get the same result?