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Reduce meniscus-driven wall climbing in SPH update shader #39

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Merged
Testtesttestestes merged 1 commit into from
Mar 10, 2026
Merged

Reduce meniscus-driven wall climbing in SPH update shader #39

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12 changes: 8 additions & 4 deletions src/sph/update.frag
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Original file line number Diff line number Diff line change
Expand Up @@ -79,7 +79,7 @@ float sdRoundedBox(vec2 p, vec2 b, float r) {
}

float wallContactThickness() {
return max(dp, 0.08);
return max(dp * 0.7, 0.05);
}

vec2 calcRoundedBoxNormal(vec2 p, vec2 b, float r) {
Expand Down Expand Up @@ -160,6 +160,7 @@ vec2 calcAcceleration() {
vec2 posDir = rot * normalLocal;
if (dist_iw < kernelRadius) {
vec2 accWKer = texture(accWallKerTex, vec2(dist_iw * rcplKernelRadius, 0.5)).xy;
float sideWallFactor = smoothstep(0.6, 0.95, abs(normalLocal.x));

float pres = max((pr_i.x + rho0 * dot(g, dist_iw * posDir)) * pr_i.y * rcplRho0, 0.0);
float repul = wallRepulsionScale * coefRepul * clamp(contactThickness - dist_iw, 0.0, 0.5 * contactThickness);
Expand All @@ -170,9 +171,12 @@ vec2 calcAcceleration() {
float relN = dot(relVel, posDir);
vec2 relT = relVel - relN * posDir;

vec2 viscWall = (-wallNormalViscScale * relN * posDir - wallTangentialViscScale * relT)
float sideTangentialScale = mix(1.0, 0.35, sideWallFactor);
float sidePressureScale = mix(1.0, 0.65, sideWallFactor);

vec2 viscWall = (-wallNormalViscScale * relN * posDir - wallTangentialViscScale * sideTangentialScale * relT)
* coefViscosity * pr_i.y * rcplRho0 * accWKer.y;
acc_i += (pres * accWKer.x - repul) * posDir + viscWall;
acc_i += (sidePressureScale * pres * accWKer.x - repul) * posDir + viscWall;
}

vec2 r_world = pos_i - u_container_pos;
Expand Down Expand Up @@ -265,7 +269,7 @@ void main(void) {
// Shared tangential drift from flask motion makes the whole contact layer move together.
vec2 wallTangent = vec2(-wallNormal.y, wallNormal.x);
float wallSlip = dot(wallVel, wallTangent);
float cohesiveSlip = wallSlip * nearWallBlend;
float cohesiveSlip = wallSlip * nearWallBlend * u_wave_amplitude * 0.35;

velh = wallVel + relVN * wallNormal + relVT + cohesiveSlip * wallTangent;
}
Expand Down