refactor shaders

res/shaders/lib/shadows.glsl

@@ -0,0 +1,32 @@
+#ifndef SHADOWS_GLSL_
+#define SHADOWS_GLSL_
+
+float calc_shadow() {
+    float shadow = 1.0;
+    if (u_enableShadows) {
+        vec4 mpos = u_shadowsMatrix * vec4(a_modelpos.xyz + a_realnormal * 0.08, 1.0);
+        vec3 projCoords = mpos.xyz / mpos.w;
+        projCoords = projCoords * 0.5 + 0.5;
+        projCoords.z -= 0.0001;
+
+        shadow = 0.0;
+        
+        if (dot(a_realnormal, u_sunDir) < 0.0) {
+            for (int x = -1; x <= 1; x++) {
+                for (int y = -1; y <= 1; y++) {
+                    shadow += texture(u_shadows, projCoords.xyz + vec3(
+                        x * (1.0 / u_shadowsRes), 
+                        y * (1.0 / u_shadowsRes), 0.0
+                    ));
+                }
+            }
+            shadow /= 9;
+            shadow = shadow * 0.5 + 0.5;
+        } else {
+            shadow = 0.5;
+        }
+    }
+    return shadow;
+}
+
+#endif // SHADOWS_GLSL_