Add existing to tracked

node_modules/@cesium/engine/Source/Shaders/Materials/ElevationBandMaterial.glsl

@@ -0,0 +1,74 @@
+uniform sampler2D heights;
+uniform sampler2D colors;
+
+// This material expects heights to be sorted from lowest to highest.
+
+float getHeight(int idx, float invTexSize)
+{
+    vec2 uv = vec2((float(idx) + 0.5) * invTexSize, 0.5);
+#ifdef OES_texture_float
+    return texture(heights, uv).x;
+#else
+    return czm_unpackFloat(texture(heights, uv));
+#endif
+}
+
+czm_material czm_getMaterial(czm_materialInput materialInput)
+{
+    czm_material material = czm_getDefaultMaterial(materialInput);
+
+    float height = materialInput.height;
+    float invTexSize = 1.0 / float(heightsDimensions.x);
+
+    float minHeight = getHeight(0, invTexSize);
+    float maxHeight = getHeight(heightsDimensions.x - 1, invTexSize);
+
+    // early-out when outside the height range
+    if (height < minHeight || height > maxHeight) {
+        material.diffuse = vec3(0.0);
+        material.alpha = 0.0;
+        return material;
+    }
+
+    // Binary search to find heights above and below.
+    int idxBelow = 0;
+    int idxAbove = heightsDimensions.x;
+    float heightBelow = minHeight;
+    float heightAbove = maxHeight;
+
+    // while loop not allowed, so use for loop with max iterations.
+    // maxIterations of 16 supports a texture size up to 65536 (2^16).
+    const int maxIterations = 16;
+    for (int i = 0; i < maxIterations; i++) {
+        if (idxBelow >= idxAbove - 1) {
+            break;
+        }
+
+        int idxMid = (idxBelow + idxAbove) / 2;
+        float heightTex = getHeight(idxMid, invTexSize);
+
+        if (height > heightTex) {
+            idxBelow = idxMid;
+            heightBelow = heightTex;
+        } else {
+            idxAbove = idxMid;
+            heightAbove = heightTex;
+        }
+    }
+
+    float lerper = heightBelow == heightAbove ? 1.0 : (height - heightBelow) / (heightAbove - heightBelow);
+    vec2 colorUv = vec2(invTexSize * (float(idxBelow) + 0.5 + lerper), 0.5);
+    vec4 color = texture(colors, colorUv);
+
+    // undo preumultiplied alpha
+    if (color.a > 0.0) 
+    {
+        color.rgb /= color.a;
+    }
+    
+    color.rgb = czm_gammaCorrect(color.rgb);
+
+    material.diffuse = color.rgb;
+    material.alpha = color.a;
+    return material;
+}