如何使用OpenGL ES弯曲3D纹理？

Question

I have tried to draw some 3D squares (with OpenGL on iPhone) and make them rotate around, now they look like a sphere.

http://i618.photobucket.com/albums/tt265/LoyalMoral/Post/ScreenShot2013-05-15at23249PM.png

But the square is flat (the first one on image below), and I want to flex it:

http://i618.photobucket.com/albums/tt265/LoyalMoral/Post/Untitled-1.jpg

someone told me that I have to use glsl, but I don't know shading language.

this is my vertex and fragment (follow Ray Wenderlich's tutorial):

// Vertex.glsl
attribute vec4 Position; 
attribute vec4 SourceColor; 

varying vec4 DestinationColor; 

uniform mat4 Projection;
uniform mat4 Modelview;

attribute vec2 TexCoordIn;
varying vec2 TexCoordOut;

void main(void) { 
    DestinationColor = SourceColor; 
    gl_Position = Projection * Modelview * Position;
    TexCoordOut = TexCoordIn;
}


// Fragment.glsl

    varying lowp vec4 DestinationColor;

varying lowp vec2 TexCoordOut;
uniform sampler2D Texture;

void main(void) {
     gl_FragColor = DestinationColor * texture2D(Texture, TexCoordOut);
}

could somebody help me? :)

Answer 1

Instead of using a quad (pair of triangles) for a square use a grid for it. Thus you will be able to place vertices of the grid manually resulting in the shape you want.