fix:TextInput support hot update;feat:add zero color and update

algorithm

shaders/base.frag

@@ -2,14 +2,51 @@
 
 in vec3 vNormal;
 in vec3 vWorldPos;
+in vec2 vUV;
 out vec4 FragColor;
 
 uniform vec3 uCameraPos;
 uniform vec3 uLightDir;
-uniform vec3 uColor;
+uniform sampler2D uHeightTex;
+uniform float uMinV;
+uniform float uMaxV;
+uniform vec2 uTexelSize;
+uniform vec3 uColorZero;
+uniform vec3 uColorLow;
+uniform vec3 uColorMid;
+uniform vec3 uColorHigh;
 
 float saturate(float x) { return clamp(x, 0.0, 1.0); }
 
+float value01(float v) {
+    return saturate((v - uMinV) / max(uMaxV - uMinV, 1e-6));
+}
+
+vec3 colorRamp(float t) {
+    if (t < 0.5) {
+        return mix(uColorLow, uColorMid, t / 0.5);
+    }
+    return mix(uColorMid, uColorHigh, (t - 0.5) / 0.5);
+}
+
+float maxNeighborValue(vec2 uv) {
+    vec2 texSizeF = 1.0 / uTexelSize;
+    ivec2 texSizeI = ivec2(max(vec2(1.0), floor(texSizeF + 0.5)));
+    ivec2 maxCoord = texSizeI - ivec2(1);
+
+    vec2 texelF = clamp(uv * texSizeF, vec2(0.0), vec2(maxCoord));
+    ivec2 base = ivec2(floor(texelF));
+    ivec2 base10 = min(base + ivec2(1, 0), maxCoord);
+    ivec2 base01 = min(base + ivec2(0, 1), maxCoord);
+    ivec2 base11 = min(base + ivec2(1, 1), maxCoord);
+
+    float v00 = texelFetch(uHeightTex, base, 0).r;
+    float v10 = texelFetch(uHeightTex, base10, 0).r;
+    float v01 = texelFetch(uHeightTex, base01, 0).r;
+    float v11 = texelFetch(uHeightTex, base11, 0).r;
+    return max(max(v00, v10), max(v01, v11));
+}
+
 void main() {
     vec3 N = normalize(vNormal);
     vec3 L = normalize(uLightDir);
@@ -19,7 +56,16 @@ void main() {
     float diff = saturate(dot(N, L));
     float spec = pow(saturate(dot(N, H)), 24.0);
 
-    vec3 col = uColor * (0.35 + 0.65 * diff);
+    float vC = texture(uHeightTex, vUV).r;
+    bool isZero = abs(vC) <= 1e-6;
+    float t = value01(vC);
+    float m = maxNeighborValue(vUV);
+    float eps = max(1e-4, 0.001 * (uMaxV - uMinV));
+    float force = smoothstep(uMaxV - eps, uMaxV, m);
+    t = max(t, force);
+    vec3 base = isZero ? uColorZero : colorRamp(t);
+
+    vec3 col = base * (0.35 + 0.65 * diff);
     col += vec3(1.0) * spec * 0.10;
     FragColor = vec4(clamp(col, 0.0, 1.0), 1.0);
 }