diff --git a/src/drawables/shapes/circle-factory.ts b/src/drawables/shapes/circle-factory.ts
index b88b5cd..ad6c8b1 100644
--- a/src/drawables/shapes/circle-factory.ts
+++ b/src/drawables/shapes/circle-factory.ts
@@ -15,6 +15,10 @@ class CircleBase extends EmptyDrawable {
   }
 }
 
+// Suffixing the GLSL names with a per-factory-invocation id lets multiple
+// circle types (e.g. different colors) coexist in one compiled shader.
+let _id = 0;
+
 /**
  * @category Drawable
  */
@@ -23,27 +27,27 @@ export const CircleFactory = (color: vec3 | vec4 | number): typeof CircleBase =>
     public static descriptor: DrawableDescriptor = {
       sdf: {
         shader: `
-            uniform vec2 circleCenters[CIRCLE_COUNT];
-            uniform float circleRadii[CIRCLE_COUNT];
-  
-            float circleMinDistance(vec2 target, out vec4 color) {
+            uniform vec2 circleCenters${_id}[CIRCLE_COUNT${_id}];
+            uniform float circleRadii${_id}[CIRCLE_COUNT${_id}];
+
+            float circleMinDistance${_id}(vec2 target, out vec4 color) {
               color = ${codeForColorAccess(color)};
               float minDistance = 1000.0;
-              for (int i = 0; i < CIRCLE_COUNT; i++) {
-                float dist = distance(circleCenters[i], target) - circleRadii[i];
+              for (int i = 0; i < CIRCLE_COUNT${_id}; i++) {
+                float dist = distance(circleCenters${_id}[i], target) - circleRadii${_id}[i];
                 minDistance = min(minDistance, dist);
               }
-  
+
               return minDistance;
             }
           `,
-        distanceFunctionName: 'circleMinDistance',
+        distanceFunctionName: `circleMinDistance${_id}`,
       },
       propertyUniformMapping: {
-        center: 'circleCenters',
-        radius: 'circleRadii',
+        center: `circleCenters${_id}`,
+        radius: `circleRadii${_id}`,
       },
-      uniformCountMacroName: 'CIRCLE_COUNT',
+      uniformCountMacroName: `CIRCLE_COUNT${_id}`,
       shaderCombinationSteps: [0, 1, 2, 3, 8, 16],
       empty: new Circle(vec2.create(), 0),
     };
@@ -60,5 +64,7 @@ export const CircleFactory = (color: vec3 | vec4 | number): typeof CircleBase =>
     }
   }
 
+  _id++;
+
   return Circle;
 };
diff --git a/src/drawables/shapes/colorful-circle.ts b/src/drawables/shapes/colorful-circle.ts
index 981db95..dbcf125 100644
--- a/src/drawables/shapes/colorful-circle.ts
+++ b/src/drawables/shapes/colorful-circle.ts
@@ -10,7 +10,7 @@ export class ColorfulCircle extends Drawable {
             uniform float colorfulCircleRadii[COLORFUL_CIRCLE_COUNT];
             uniform int colorfulCircleColorIndex[COLORFUL_CIRCLE_COUNT];
   
-            float circleMinDistance(vec2 target, out vec4 color) {
+            float colorfulCircleMinDistance(vec2 target, out vec4 color) {
               float minDistance = 1000.0;
               for (int i = 0; i < COLORFUL_CIRCLE_COUNT; i++) {
                 float dist = distance(colorfulCircleCenters[i], target) - colorfulCircleRadii[i];
@@ -23,7 +23,7 @@ export class ColorfulCircle extends Drawable {
               return minDistance;
             }
           `,
-      distanceFunctionName: 'circleMinDistance',
+      distanceFunctionName: 'colorfulCircleMinDistance',
     },
     propertyUniformMapping: {
       center: 'colorfulCircleCenters',
diff --git a/src/drawables/shapes/inverted-tunnel-factory.ts b/src/drawables/shapes/inverted-tunnel-factory.ts
index e0d3c4e..9fe2d01 100644
--- a/src/drawables/shapes/inverted-tunnel-factory.ts
+++ b/src/drawables/shapes/inverted-tunnel-factory.ts
@@ -36,7 +36,12 @@ export const InvertedTunnelFactory = (
         uniform float fromRadii[INVERTED_TUNNEL_COUNT];
         uniform float toRadii[INVERTED_TUNNEL_COUNT];
 
-        uniform sampler2D noiseTexture;
+        // Other drawables share this declaration; the include guard keeps
+        // the combined shader from declaring it twice.
+        #ifndef NOISE_TEXTURE_DECLARED
+        #define NOISE_TEXTURE_DECLARED
+          uniform sampler2D noiseTexture;
+        #endif
 
         #ifdef WEBGL2_IS_AVAILABLE
           float invertedTunnelTerrain(float h) {
diff --git a/src/drawables/shapes/noisy-polygon-factory.ts b/src/drawables/shapes/noisy-polygon-factory.ts
index aba0d93..e021f2a 100644
--- a/src/drawables/shapes/noisy-polygon-factory.ts
+++ b/src/drawables/shapes/noisy-polygon-factory.ts
@@ -24,16 +24,25 @@ export const NoisyPolygonFactory = (
           uniform float noisyPolygon${vertexCount}Lengths[NOISY_POLYGON${vertexCount}_COUNT];
           uniform float noisyPolygon${vertexCount}Randoms[NOISY_POLYGON${vertexCount}_COUNT];
 
-          uniform sampler2D noiseTexture;
+          // Other drawables (and other vertex-count variants of this one)
+          // share these declarations; the include guards keep the combined
+          // shader from declaring them twice.
+          #ifndef NOISE_TEXTURE_DECLARED
+          #define NOISE_TEXTURE_DECLARED
+            uniform sampler2D noiseTexture;
+          #endif
 
-          #ifdef WEBGL2_IS_AVAILABLE
-            float myTerrain(vec2 h) {
-              return texture(noiseTexture, h)[0] - 0.5;
-            }
-          #else
-            float myTerrain(vec2 h) {
-              return texture2D(noiseTexture, h)[0] - 0.5;
-            }
+          #ifndef MY_TERRAIN_DECLARED
+          #define MY_TERRAIN_DECLARED
+            #ifdef WEBGL2_IS_AVAILABLE
+              float myTerrain(vec2 h) {
+                return texture(noiseTexture, h)[0] - 0.5;
+              }
+            #else
+              float myTerrain(vec2 h) {
+                return texture2D(noiseTexture, h)[0] - 0.5;
+              }
+            #endif
           #endif
 
           vec2 noisyPolygon${vertexCount}LineDistance(vec2 target, vec2 from, vec2 to) {