shader_type spatial;
render_mode cull_disabled;

uniform sampler2D npcTexture : filter_nearest;
uniform int frame;
uniform int direction;

const int FRAMES = 3;
const int DIRECTIONS = 4;
//const bool BILLBOARD_ROTATION_LOCK = false;

void vertex() {
	//if(BILLBOARD_ROTATION_LOCK) {
	    //mat4 modified_model_view = VIEW_MATRIX * mat4(
	        //INV_VIEW_MATRIX[0],
	        //INV_VIEW_MATRIX[1],
	        //INV_VIEW_MATRIX[2],
	        //MODEL_MATRIX[3]
	    //);
	    //MODELVIEW_MATRIX = modified_model_view;
	//} else {
	    //mat4 modified_model_view = VIEW_MATRIX * mat4(
	        //INV_VIEW_MATRIX[0],
	        //MODEL_MATRIX[1],
	        //MODEL_MATRIX[2],
	        //MODEL_MATRIX[3]
	    //);
	    //MODELVIEW_MATRIX = modified_model_view;
	//}

	vec2 tileSize = vec2(1.0 / float(FRAMES), 1.0 / float(DIRECTIONS));
	vec2 topLeft = tileSize * vec2(float(frame % FRAMES), float(direction % DIRECTIONS));
	vec2 bottomRight = topLeft + tileSize;

	if(VERTEX_ID == 3) {
		UV = topLeft;
	} else if(VERTEX_ID == 2) {
		UV = vec2(bottomRight.x, topLeft.y);
	} else if(VERTEX_ID == 1) {
		UV = vec2(topLeft.x, bottomRight.y);
	} else if(VERTEX_ID == 0) {
		UV = bottomRight;
	}
}

void fragment() {
	vec4 npcColor = texture(npcTexture, UV);

	// Remove PINK background
	if(npcColor.r == 1.0 && npcColor.g == 0.0 && npcColor.b == 1.0)
		discard;

	// Remove GREEN borders
	if(npcColor.r == 0.00392156862745 && npcColor.g == 1.0 && npcColor.b == 0.0)
		discard;

	ALBEDO.rgb = npcColor.rgb;
}