Perspective correct texturing of trapezoid in OpenGL ES 2.0

Question

I have drawn a textured trapezoid, however the result does not appear as I had intended.

Instead of appearing as a single unbroken quadrilateral, a discontinuity occ

Answer 1

What you are trying here is Skewed texture. A sample fragment shader is as follows :

precision mediump float;
varying vec4 vtexCoords;
uniform sampler2D sampler;

void main()
{
   gl_FragColor = texture2DProj(sampler,vtexCoords);
}

2 things which should look different are :

1) We are using varying vec4 vtexCoords; . Texture co-ordinates are 4 dimensional. 2) texture2DProj() is used instead of texture2D()

Based on length of small and large side of your trapezium you will assign texture co-ordinates. Following URL might help : http://www.xyzw.us/~cass/qcoord/