Impressum

		attribute vec3 inputPosition;
		attribute vec4 inputColor;

		varying vec3 forFragColor;

		void main() 
		{
		  forFragColor = inputColor.rgb;
		  gl_Position = vec4(inputPosition*1000.0, 1.0);
		}

                // shader by Franz Mandl
		precision highp float;

		uniform float thetime;
		uniform float resx;
		uniform float resy;
		vec2 sco;
		vec3 lightPos=vec3(0,.7,.9),cres,rs,rd,sp;
		float screenYszf=400.0,screenXszf=512.0,cellsize;
		
		vec3 shade( vec3 pos )
		{
			vec3 wDir = normalize(rd);
			float dist=length(rs-pos);
			return dist*(vec3(1.0,1.0,1.0)*pow(dot(normalize(lightPos-pos),wDir),2.0));
		}
		
		float rand(float seedx,float seedy,int level){                
			
			return abs(sin(pow(abs(seedx),float(level)))+cos(pow(abs(seedy),float(level))));
		}
	
	        float getHeight(vec3 sp){
	                float height=0.0;

	                for(int lcounter=0;lcounter<10;lcounter++){
	                  height+=rand(sp.x,sp.z,lcounter)/pow(2.0,float(lcounter)+1.0);
	                }

	                return height;
	          
	        }
		
		void castLand(){
		        cellsize=.01;
		        vec3 pos,norm,color;float tsp;
			float h1=0.0;float h2=0.0;float h3=0.0;float dist=0.0001;

			for (int iter=0;iter<160;iter++){
			        dist+=dist*1.09;
				sp=rs+rd*dist;
				if (dist>10.0) break;
				h1=getHeight(sp);
				h2=getHeight(sp+vec3(cellsize,0,0));
				h3=getHeight(sp+vec3(0,0,cellsize));
				cross(vec3(cellsize,h2,0.0)-vec3(.0,h1,.0),(vec3(.0,h3,cellsize)-vec3(.0,h1,.0)));
				norm=normalize(norm);
				if (h1>sp.y) {	
				       // cres+=vec3(9.0,5.0,0.0)*fract(sin(dot(vec2(sp.z,sp.x*.9),vec2(999.0,.001)))*9.0)/9.0+.1;
				        break;
				}
			}
			
			cres+=shade(rd)*sp;
			return;
		}
		
		void main(void)
		{
			sco.x=((gl_FragCoord.x-screenXszf/2.0)/screenXszf)*2.0*resx/resy;
			sco.y=((gl_FragCoord.y-screenYszf/2.0)/screenYszf)*2.0;
			rd=normalize(vec3(0.0,-0.2,0.8) + sco.y*vec3(0,1,0)+sco.x*vec3(1,0,0));                
			rs=vec3(0,1.5,1)+vec3(0.3,0,0)*thetime/200000.0;
			cres=vec3(0);
			castLand();
			gl_FragColor  = vec4(cres,1);
		}