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shader_type spatial;
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render_mode cull_disabled;
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uniform float wind_speed = 0.2;
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uniform float wind_strength = 2.0;
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// How big, in world space, is the noise texture
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// wind will tile every wind_texture_tile_size
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uniform float wind_texture_tile_size = 20.0;
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uniform float wind_vertical_strength = 0.3;
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uniform vec2 wind_horizontal_direction = vec2(1.0, 0.5);
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uniform sampler2D color_ramp : hint_default_black;
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// we need a tiling noise here!
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uniform sampler2D wind_noise : hint_default_black;
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uniform vec3 character_position;
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uniform float character_radius = 3.0;
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uniform sampler2D character_distance_falloff_curve : hint_default_black;
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uniform float character_push_strength = 1.0;
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varying float debug_wind;
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void vertex() {
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vec3 world_vert = (MODEL_MATRIX * vec4(VERTEX, 1.0)).xyz;
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vec2 normalized_wind_direction = normalize(wind_horizontal_direction);
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vec2 world_uv = world_vert.xz / wind_texture_tile_size + normalized_wind_direction * TIME * wind_speed;
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// we displace only the top part of the mesh
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// note that this means that the mesh needs to have UV in a way that the bottom of UV space
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// is at the top of the mesh
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float displacement_affect = (1.0 - UV.y);
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float wind_noise_intensity = (textureLod(wind_noise, world_uv, 0.0).r - 0.5);
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// We convert the direction of the wind into vertex space from world space
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// if we used it directly in vertex space, rotated blades of grass wouldn't behave properly
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vec2 vert_space_horizontal_dir =
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(inverse(MODEL_MATRIX) * vec4(wind_horizontal_direction, 0.0, 0.0)).xy;
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vert_space_horizontal_dir = normalize(vert_space_horizontal_dir);
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vec3 bump_wind = vec3(
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wind_noise_intensity * vert_space_horizontal_dir.x,
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1.0 - wind_noise_intensity,
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wind_noise_intensity * vert_space_horizontal_dir.y);
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normalize(bump_wind);
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bump_wind *= vec3(wind_strength, wind_vertical_strength, wind_strength);
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vec3 dir_to_character = character_position - MODEL_MATRIX[3].xyz;
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float distance_to_character = length(dir_to_character);
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float falloff = 1.0 - smoothstep(0.0, 1.0, distance_to_character/character_radius);
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dir_to_character = (inverse(MODEL_MATRIX) * vec4(dir_to_character, 0.0)).xyz;
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dir_to_character = normalize(dir_to_character);
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float falloff_curve = texture(character_distance_falloff_curve, vec2(falloff)).x;
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vec3 vertex_offset = bump_wind * displacement_affect + normalize(-dir_to_character) * falloff_curve * character_push_strength * displacement_affect;
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vertex_offset = smoothstep(0.0, 1.0, vertex_offset); // VERTEX.y越大，扰动幅度越大
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VERTEX += normalize(-dir_to_character) * falloff_curve * character_push_strength * displacement_affect;
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}
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void fragment() {
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ALBEDO = texture(color_ramp, vec2(1.0 - UV.y, 0)).rgb ;
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} |