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Diffstat (limited to 'game/addons/zylann.hterrain/tools/generator/shaders/perlin_noise.gdshader')
-rw-r--r-- | game/addons/zylann.hterrain/tools/generator/shaders/perlin_noise.gdshader | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/game/addons/zylann.hterrain/tools/generator/shaders/perlin_noise.gdshader b/game/addons/zylann.hterrain/tools/generator/shaders/perlin_noise.gdshader new file mode 100644 index 0000000..7609f7c --- /dev/null +++ b/game/addons/zylann.hterrain/tools/generator/shaders/perlin_noise.gdshader @@ -0,0 +1,211 @@ +shader_type canvas_item; +// Required only because we use all 4 channels to encode floats into RGBA8 +render_mode blend_disabled; + +#include "res://addons/zylann.hterrain/shaders/include/heightmap.gdshaderinc" + +uniform vec2 u_offset; +uniform float u_scale = 0.02; +uniform float u_base_height = 0.0; +uniform float u_height_range = 100.0; +uniform int u_seed; +uniform int u_octaves = 5; +uniform float u_roughness = 0.5; +uniform float u_curve = 1.0; +uniform float u_terrain_size = 513.0; +uniform float u_tile_size = 513.0; +uniform sampler2D u_additive_heightmap; +uniform float u_additive_heightmap_factor = 0.0; +uniform vec2 u_uv_offset; +uniform vec2 u_uv_scale = vec2(1.0, 1.0); + +uniform float u_island_weight = 0.0; +// 0: smooth transition, 1: sharp transition +uniform float u_island_sharpness = 0.0; +// 0: edge is min height (island), 1: edge is max height (canyon) +uniform float u_island_height_ratio = 0.0; +// 0: round, 1: square +uniform float u_island_shape = 0.0; + +//////////////////////////////////////////////////////////////////////////////// +// Perlin noise source: +// https://github.com/curly-brace/Godot-3.0-Noise-Shaders +// +// GLSL textureless classic 2D noise \"cnoise\", +// with an RSL-style periodic variant \"pnoise\". +// Author: Stefan Gustavson (stefan.gustavson@liu.se) +// Version: 2011-08-22 +// +// Many thanks to Ian McEwan of Ashima Arts for the +// ideas for permutation and gradient selection. +// +// Copyright (c) 2011 Stefan Gustavson. All rights reserved. +// Distributed under the MIT license. See LICENSE file. +// https://github.com/stegu/webgl-noise +// + +vec4 mod289(vec4 x) { + return x - floor(x * (1.0 / 289.0)) * 289.0; +} + +vec4 permute(vec4 x) { + return mod289(((x * 34.0) + 1.0) * x); +} + +vec4 taylorInvSqrt(vec4 r) { + return 1.79284291400159 - 0.85373472095314 * r; +} + +vec2 fade(vec2 t) { + return t * t * t * (t * (t * 6.0 - 15.0) + 10.0); +} + +// Classic Perlin noise +float cnoise(vec2 P) { + vec4 Pi = floor(vec4(P, P)) + vec4(0.0, 0.0, 1.0, 1.0); + vec4 Pf = fract(vec4(P, P)) - vec4(0.0, 0.0, 1.0, 1.0); + Pi = mod289(Pi); // To avoid truncation effects in permutation + vec4 ix = Pi.xzxz; + vec4 iy = Pi.yyww; + vec4 fx = Pf.xzxz; + vec4 fy = Pf.yyww; + + vec4 i = permute(permute(ix) + iy); + + vec4 gx = fract(i * (1.0 / 41.0)) * 2.0 - 1.0 ; + vec4 gy = abs(gx) - 0.5 ; + vec4 tx = floor(gx + 0.5); + gx = gx - tx; + + vec2 g00 = vec2(gx.x,gy.x); + vec2 g10 = vec2(gx.y,gy.y); + vec2 g01 = vec2(gx.z,gy.z); + vec2 g11 = vec2(gx.w,gy.w); + + vec4 norm = taylorInvSqrt(vec4(dot(g00, g00), dot(g01, g01), dot(g10, g10), dot(g11, g11))); + g00 *= norm.x; + g01 *= norm.y; + g10 *= norm.z; + g11 *= norm.w; + + float n00 = dot(g00, vec2(fx.x, fy.x)); + float n10 = dot(g10, vec2(fx.y, fy.y)); + float n01 = dot(g01, vec2(fx.z, fy.z)); + float n11 = dot(g11, vec2(fx.w, fy.w)); + + vec2 fade_xy = fade(Pf.xy); + vec2 n_x = mix(vec2(n00, n01), vec2(n10, n11), fade_xy.x); + float n_xy = mix(n_x.x, n_x.y, fade_xy.y); + return 2.3 * n_xy; +} +//////////////////////////////////////////////////////////////////////////////// + +float get_fractal_noise(vec2 uv) { + float scale = 1.0; + float sum = 0.0; + float amp = 0.0; + int octaves = u_octaves; + float p = 1.0; + uv.x += float(u_seed) * 61.0; + + for (int i = 0; i < octaves; ++i) { + sum += p * cnoise(uv * scale); + amp += p; + scale *= 2.0; + p *= u_roughness; + } + + float gs = sum / amp; + return gs; +} + +// x is a ratio in 0..1 +float get_island_curve(float x) { + return smoothstep(min(0.999, u_island_sharpness), 1.0, x); +// float exponent = 1.0 + 10.0 * u_island_sharpness; +// return pow(abs(x), exponent); +} + +float smooth_union(float a, float b, float k) { + float h = clamp(0.5 + 0.5 * (b - a) / k, 0.0, 1.0); + return mix(b, a, h) - k * h * (1.0 - h); +} + +float squareish_distance(vec2 a, vec2 b, float r, float s) { + vec2 v = b - a; + // TODO This is brute force but this is the first attempt that gave me a "rounded square" distance, + // where the "roundings" remained constant over distance (not the case with standard box SDF) + float da = -smooth_union(v.x+s, v.y+s, r)+s; + float db = -smooth_union(s-v.x, s-v.y, r)+s; + float dc = -smooth_union(s-v.x, v.y+s, r)+s; + float dd = -smooth_union(v.x+s, s-v.y, r)+s; + return max(max(da, db), max(dc, dd)); +} + +// This is too sharp +//float squareish_distance(vec2 a, vec2 b) { +// vec2 v = b - a; +// // Manhattan distance would produce a "diamond-shaped distance". +// // This gives "square-shaped" distance. +// return max(abs(v.x), abs(v.y)); +//} + +float get_island_distance(vec2 pos, vec2 center, float terrain_size) { + float rd = distance(pos, center); + float sd = squareish_distance(pos, center, terrain_size * 0.1, terrain_size); + return mix(rd, sd, u_island_shape); +} + +// pos is in terrain space +float get_height(vec2 pos) { + float h = 0.0; + + { + // Noise (0..1) + // Offset and scale for the noise itself + vec2 uv_noise = (pos / u_terrain_size + u_offset) * u_scale; + h = 0.5 + 0.5 * get_fractal_noise(uv_noise); + } + + // Curve + { + h = pow(h, u_curve); + } + + // Island + { + float terrain_size = u_terrain_size; + vec2 island_center = vec2(0.5 * terrain_size); + float island_height_ratio = 0.5 + 0.5 * u_island_height_ratio; + float island_distance = get_island_distance(pos, island_center, terrain_size); + float distance_ratio = clamp(island_distance / (0.5 * terrain_size), 0.0, 1.0); + float island_ratio = u_island_weight * get_island_curve(distance_ratio); + h = mix(h, island_height_ratio, island_ratio); + } + + // Height remapping + { + h = u_base_height + h * u_height_range; + } + + // Additive heightmap + { + vec2 uv = pos / u_terrain_size; + float ah = sample_heightmap(u_additive_heightmap, uv); + h += u_additive_heightmap_factor * ah; + } + + return h; +} + +void fragment() { + // Handle screen padding: transform UV back into generation space. + // This is in tile space actually...? it spans 1 unit across the viewport, + // and starts from 0 when tile (0,0) is generated. + // Maybe we could change this into world units instead? + vec2 uv_tile = (SCREEN_UV + u_uv_offset) * u_uv_scale; + + float h = get_height(uv_tile * u_tile_size); + + COLOR = encode_height_to_viewport(h); +} |