Tunnel Speed Lines

This is a 3D Particles Shader done in Godot 3.4.stable, to draw Tunnel Speed Lines.

Tunnel dimensions are set by Tunnel Radius and Tunnel Length.

Velocity is set by Lifetime ( = Preprocess ).

Draw Pass 1 draws Quad-stripes with editable size x=3.0, y=0.4.

Draw Pass 1 Material has a Shader Param Texture Albedo, to use your own texture with alpha channel.

Shader code

shader_type particles;

uniform float tunnel_radius : hint_range( 0.0, 10.0 ) = 2.0;
uniform float tunnel_length : hint_range( 0.0, 100.0 ) = 50.0;

float rand_from_seed(in uint seed) {
	int k;
	int s = int(seed);
	if (s == 0)
	s = 305420679;
	k = s / 127773;
	s = 16807 * (s - k * 127773) - 2836 * k;
	if (s < 0)
	s += 2147483647;
	seed = uint(s);
	return float(seed % uint(65536)) / 65535.0;
}

uint hash(uint x) {
	x = ((x >> uint(16)) ^ x) * uint(73244475);
	x = ((x >> uint(16)) ^ x) * uint(73244475);
	x = (x >> uint(16)) ^ x;
	return x;
}

void vertex() {
	if (RESTART) {
		uint alt_seed1 = hash(NUMBER + uint(1) + RANDOM_SEED);
		// set particle position in model space with tunnel_radius and tunnel_length
		float angle_rand = rand_from_seed( alt_seed1 ) * 6.283185;
		TRANSFORM[3].x = tunnel_length;
		TRANSFORM[3].y = sin( angle_rand ) * tunnel_radius;
		TRANSFORM[3].z = cos( angle_rand ) * tunnel_radius;
		// calculate VELOCITY in negative x direction
		VELOCITY.x = -tunnel_length / LIFETIME;
		// calculate 2D normal and send it to \"Pass 1\" shader with CUSTOM variable
		CUSTOM.yz = vec2( sin( angle_rand - 1.570796 ), cos( angle_rand - 1.570796 ) );
	}
}




shader_type spatial;

render_mode unshaded;
uniform sampler2D texture_albedo : hint_albedo;

void vertex() {
	// caculate world_y: get local 2D normal from particle shader variable CUSTOM.yz and transform it from model space to world space
	vec4 world_y = WORLD_MATRIX * vec4( 0.0, INSTANCE_CUSTOM.y, INSTANCE_CUSTOM.z, 0.0);
	// calculate world_z by the cross product of WORLD_MATRIX[0] ( = world_x) and world_y
	vec4 world_z = vec4( cross( WORLD_MATRIX[0].xyz, world_y.xyz ), 0.0 );
	// calculate model space to view space
	MODELVIEW_MATRIX = INV_CAMERA_MATRIX * mat4( WORLD_MATRIX[0], world_y, world_z, WORLD_MATRIX[3] );
}

void fragment() {
	ALBEDO = texture( texture_albedo, UV ).rgb;
	ALPHA = texture( texture_albedo, UV ).a;
}

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