// This shader is mostly an adaptation of the shader found at
//  http://www.bonzaisoftware.com/water_tut.html and its glsl conversion
//  available at http://forum.bonzaisoftware.com/viewthread.php?tid=10
//  © Michael Horsch - 2005
//  Major update and revisions - 2011-10-07
//  © Emilian Huminiuc and Vivian Meazza

#version 120

varying vec4 waterTex1;
varying vec4 waterTex2;
//varying vec4 waterTex4;

varying vec3 viewerdir;
varying vec3 lightdir;
varying vec3 normal;

uniform float osg_SimulationTime;
uniform float WindE, WindN;

/////// functions /////////

void rotationmatrix(in float angle, out mat4 rotmat)
	{
	rotmat = mat4( cos( angle ), -sin( angle ), 0.0, 0.0,
		sin( angle ),  cos( angle ), 0.0, 0.0,
		0.0         ,  0.0         , 1.0, 0.0,
		0.0         ,  0.0         , 0.0, 1.0 );
	}

void main(void)
	{
	mat4 RotationMatrix;
	vec3 N = normalize(gl_Normal);
	normal = N;

	vec4 ecPosition = gl_ModelViewMatrix * gl_Vertex;

	viewerdir = vec3(gl_ModelViewMatrixInverse[3]) - vec3(gl_Vertex);
	lightdir = normalize(vec3(gl_ModelViewMatrixInverse * gl_LightSource[0].position));

	//waterTex4 = vec4(ecPosition.xzy, 0.0 );

	vec4 t1 = vec4(0.0, osg_SimulationTime * 0.005217, 0.0, 0.0);
	vec4 t2 = vec4(0.0, osg_SimulationTime * -0.0012, 0.0, 0.0);

	float Angle;

	float windFactor = sqrt(pow(abs(WindE),2)+pow(abs(WindN),2)) * 0.05;

	if (WindN == 0.0 && WindE == 0.0) {
		Angle = 0.0;
		}else{
			Angle = atan(-WindN, WindE) - atan(1.0);
		}

	rotationmatrix(Angle, RotationMatrix);
	waterTex1 = gl_MultiTexCoord0 * RotationMatrix - t1 * windFactor;

	rotationmatrix(Angle, RotationMatrix);
	waterTex2 = gl_MultiTexCoord0 * RotationMatrix - t2 * windFactor;

	//     fog_Func(fogType);
	gl_Position = ftransform();
	}