52 lines
1.7 KiB
GLSL
52 lines
1.7 KiB
GLSL
vGrassUv = uv;
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vec4 worldPos = modelMatrix * instanceMatrix * vec4(0.0, 0.0, 0.0, 1.0);
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float gx = worldPos.x;
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float gz = worldPos.z;
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vec2 mainWindDir = normalize(vec2(1.0, 0.6));
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float windSpeed = 1.5;
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float windTime = uTime * windSpeed;
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vec2 windSamplePos = (worldPos.xz * 0.05) - (mainWindDir * windTime * 0.2);
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float windBase = fbm(windSamplePos * 0.8) * 0.4 + 0.2;
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float gustNoise = fbm(windSamplePos * 0.4);
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float gust = pow(gustNoise, 3.0) * 1.8;
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float totalWind = windBase + gust;
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float phase = gx * 0.5 + gz * 0.3;
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float spring = sin(uTime * 2.0 + phase) * 0.06 + sin(uTime * 4.5 + phase * 1.5) * 0.03;
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float angleNoise = fbm(windSamplePos * 2.0 + uTime * 0.1) - 0.5;
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vec2 windDir = normalize(mainWindDir + vec2(-mainWindDir.y, mainWindDir.x) * angleNoise * 0.4);
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// taper (fade)
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float taperFactor = uv.y * uv.y * uv.y;
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float taper = 1.0 - taperFactor * 0.85;
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transformed.x *= taper;
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transformed.z *= taper;
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// curve
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float curveVal = fbm(vec2(gx, gz) * 0.5);
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float curveStrength = 1.5 + curveVal * 2.5;
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float curveAmount = uv.y * uv.y * curveStrength;
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vec2 curveDir = normalize(vec2(curveVal, fbm(vec2(gz, gx))) - 0.5);
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transformed.x += curveAmount * curveDir.x * 0.4;
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transformed.z += curveAmount * curveDir.y * 0.4;
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// sway
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float swayAmount = (totalWind + spring) * uv.y * uv.y;
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transformed.x += swayAmount * windDir.x;
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transformed.z += swayAmount * windDir.y;
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transformed.y -= abs(swayAmount) * 0.2;
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// normal comp
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vec2 totalBend = curveDir * curveAmount * 0.4 + windDir * swayAmount;
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float bendMag = length(totalBend);
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vec3 bentNormal = normalize(vec3(-totalBend.x * 0.5, 1.0, -totalBend.y * 0.5));
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// normal mix
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objectNormal = normalize(mix(vec3(0.0, 1.0, 0.0), bentNormal, uv.y));
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vWorldPos = (modelMatrix * instanceMatrix * vec4(transformed, 1.0)).xyz; |