SHADER模块整理，初始化代码移至main

Zframework/light/shadowMap.glsl

@@ -0,0 +1,21 @@
+#define PI 3.14
+extern float yresolution;
+vec4 effect(vec4 color,Image texture,vec2 texture_coords,vec2 screen_coords){
+	//Iterate through the occluder map's y-axis.
+	for(float y=0.;y<yresolution;y++){
+		//cartesian to polar
+		// y/yresolution=distance to light source(0~1)
+		vec2 norm=vec2(texture_coords.s,y/yresolution)*2.-1.;
+		float theta=PI*1.5+norm.x*PI;
+		float r=(1.+norm.y)*0.5;
+
+		//sample from solid
+		if(
+			Texel(texture,(
+				vec2(-r*sin(theta),-r*cos(theta))*0.5+0.5//coord of solid sampling
+			))
+			.a>0.1
+		)return vec4(vec3(y/yresolution),1.);//collision check, alpha>0.1 means transparent
+	}
+	return vec4(1.,1.,1.,1.);//return max distance 1
+}