varying vec3 lightDir,normal;uniform float time;uniform sampler2D myTexture;void main(){ gl_TexCoord[0] = gl_MultiTexCoord0; lightDir = normalize(vec3(gl_LightSource[0].position)); normal = gl_NormalMatrix * gl_Normal; vec4 color = texture2D(myTexture, vec2(gl_TexCoord[0])); vec3 pos = gl_Vertex + (gl_Normal * color.z); vec4 pos4 = vec4(pos.x, pos.y, pos.z, 1.0); gl_Position = vec4(gl_ModelViewProjectionMatrix * pos4);} In this version I've cut down a bit and removed everything except the vertex modification.
uniform sampler2D myTexture;void main(){ // getting the texture coords for the sampler gl_TexCoord[0] = gl_MultiTexCoord0; // In this case my source image "heightmap" is RGBA - // - and height is only 8-bits in the alpha channel. // This is a bit rubbish but yours could be a full float format. vec4 heightColour = texture2D(myTexture, gl_TexCoord[0].st); // up is the direction we want to move the vertex, this was called // "normal" in the version above. const vec3 up = vec3(0.0, 1.0, 0.0); // now we modify the position of the gl_Vertex // this last section is a bit messy and could be improved, a lot!!! vec3 pos = gl_Vertex + (up * heightColour.a); vec4 pos4 = vec4(pos.x, pos.y, pos.z, 1.0); gl_Position = vec4(gl_ModelViewProjectionMatrix * pos4);} There nothing too it.
All I'm really doing is writing the height value into a texture, and then sampling it in the vertex shader. I use it to scale a vector called "normal" in the original shader, or "up" in the second listing. This gives me a scaled vector that I can add to the gl_Vertex that we're currently dealing with and set the gl_Position using it.
As you can see from the comments I've added the version I've given you is not an ideal situation. For a start I'm only using 8-bits of the 32-bit format from my texture. I don't need the extra precision so I save one texture channel but you will probably want to use a floating point texture format, or encode your height into the full texture.
You'll want to add a pre-generated normal map to the above and write your own fragment shader but this should get you started. It only took me a few of hours to learn how to do this the first time and if you can write a fft water simulation I'm sure you're up to it!
Andy
