/* TODO: Recalculate normals, cleanup

 */

shader_type spatial;

// player_pos updated in Ground.gd, used to calculate distance from player

uniform vec3 player_pos = vec3(0.0, 0.0, 0.0);

// Set "active" to  false  to turn off the displacement shader.

uniform bool active = true;

// Set "remap_normals" to true if you want lighting to take place after displacement

uniform bool remap_normals = true;

// Use RADIUS to determine how warped the world should be.

uniform float RADIUS = 10.0;

uniform bool hang = false;

void fragment() {

	// Add color

	ALBEDO = vec3(0.1, 0.3, 0.05);

}

void vertex() {

	// Vertex displacement math, as a function of dist_z, dist_y

	float dist_z = VERTEX.z - player_pos.z;

	float dist_y = VERTEX.y;

	// Dz and theta is calculated from RADIUS for use in the transform. 

	float Dz = PI*RADIUS/2.0;

	float theta = dist_z / RADIUS;

	

	// Calculate which "side" we're on

	// 1 and -1 represent "hanging towel"

	// 0 represents the "rolling log" part

	int side;

	if (active) {

		if (dist_z > Dz) {

			side = 1;

		} else if (dist_z < -Dz) {

			side = -1;

		} else {

			side = 0;

		}

		

		// set side = 0 if you want a log without "hanging sides"

		if (!hang) { side = 0; }

		if (side == 1) {

			// positive vertical side

			VERTEX.y = -(dist_z - Dz) - RADIUS;

			VERTEX.z = dist_y + RADIUS;

		}

		if (side == -1) {

			// negative vertical side

			VERTEX.y = (dist_z + Dz) - RADIUS;

			VERTEX.z = - (dist_y + RADIUS);

		}

		if (side == 0) {

			// rolling log

			VERTEX.y = (dist_y + RADIUS)*cos(theta) - RADIUS;

			VERTEX.z = (dist_y + RADIUS)*sin(theta) ;

		}

		// reposition world vertices

		VERTEX.z += player_pos.z;

	}

	// todo - recalculate normals

	if (remap_normals) {

		if (side == 1) {

			//vec3 normal = normalize(vec3(NORMAL.x, -NORMAL.z, NORMAL.y));

			vec3 normal = normalize(vec3(0.0, 1.0, 0.0));

			NORMAL = normal;

		} else if (side == -1) {

			//vec3 normal = normalize(vec3(NORMAL.x, NORMAL.z, -NORMAL.y));

			vec3 normal = normalize(vec3(0.0, 1.0, 0.0));

			NORMAL = normal;

		} else if (side == 0) {

			// todo - check this math!

			vec3 normal = normalize(vec3(

				NORMAL.x,

				NORMAL.y * cos(theta) - NORMAL.z * sin(theta),

				NORMAL.z * cos(theta) + NORMAL.z * sin(theta)

			));

			NORMAL = normal;

		}

	}

}