Displays a fake ground plane that doesn't need to correspond to geometry. Useful for creating a ground plane that extends to the horizon without requiring infinite geometry.

fake_ground_plane.gdshader

shader_type spatial;

uniform sampler2D ground_texture:source_color, repeat_enable, filter_linear_mipmap;

uniform float ground_height = -1.0;
uniform float scale = 2.0;

varying vec3 world_position;
varying vec3 cam_pos;

void vertex() {
	NORMAL =vec3(0.0, 1.0, 0.0); // normal should always face up
	world_position = (MODEL_MATRIX * vec4(VERTEX, 1.0)).xyz;
	cam_pos = CAMERA_POSITION_WORLD  + EYE_OFFSET;
}

void fragment() {
	vec3 view_dir = normalize(world_position - cam_pos);
	if (view_dir.y > 0.0) // only show it below the horizon
		discard;
	vec2 ground_uv = (vec2(view_dir.x, view_dir.z) * abs(cam_pos.y - ground_height) / view_dir.y - vec2(cam_pos.x, cam_pos.z)) / scale;
	
	ALBEDO = texture(ground_texture, ground_uv).rgb;
}