Allow sampler bindings to run custom behavior after they get bound

src/main/java/net/coderbot/iris/gl/program/ProgramBuilder.java

@@ -103,7 +103,7 @@ public boolean hasSampler(String name) {
 	}
 
 	@Override
-	public boolean addDynamicSampler(IntSupplier sampler, String... names) {
-		return samplers.addDynamicSampler(sampler, names);
+	public boolean addDynamicSampler(IntSupplier sampler, Runnable postBind, String... names) {
+		return samplers.addDynamicSampler(sampler, postBind, names);
 	}
 }

src/main/java/net/coderbot/iris/gl/program/ProgramSamplers.java

@@ -110,7 +110,7 @@ public boolean hasSampler(String name) {
 		 * @return false if this sampler is not active, true if at least one of the names referred to an active sampler
 		 */
 		@Override
-		public boolean addDynamicSampler(IntSupplier sampler, String... names) {
+		public boolean addDynamicSampler(IntSupplier sampler, Runnable postBind, String... names) {
 			boolean used = false;
 
 			for (String name : names) {
@@ -139,7 +139,7 @@ public boolean addDynamicSampler(IntSupplier sampler, String... names) {
 				return false;
 			}
 
-			samplers.add(new SamplerBinding(nextUnit, sampler));
+			samplers.add(new SamplerBinding(nextUnit, sampler, postBind));
 
 			remainingUnits -= 1;
 			nextUnit += 1;

src/main/java/net/coderbot/iris/gl/sampler/SamplerBinding.java

@@ -8,14 +8,17 @@
 public class SamplerBinding {
 	private final int textureUnit;
 	private final IntSupplier texture;
+	private final Runnable postBind;
 
-	public SamplerBinding(int textureUnit, IntSupplier texture) {
+	public SamplerBinding(int textureUnit, IntSupplier texture, Runnable postBind) {
 		this.textureUnit = textureUnit;
 		this.texture = texture;
+		this.postBind = postBind;
 	}
 
 	public void update() {
 		RenderSystem.activeTexture(GL20C.GL_TEXTURE0 + textureUnit);
 		RenderSystem.bindTexture(texture.getAsInt());
+		this.postBind.run();
 	}
 }

src/main/java/net/coderbot/iris/gl/sampler/SamplerHolder.java

@@ -5,5 +5,9 @@
 public interface SamplerHolder {
 	void addExternalSampler(int textureUnit, String... names);
 	boolean hasSampler(String name);
-	boolean addDynamicSampler(IntSupplier sampler, String... names);
+	boolean addDynamicSampler(IntSupplier sampler, Runnable postBind, String... names);
+
+	default boolean addDynamicSampler(IntSupplier sampler, String... names) {
+		return addDynamicSampler(sampler, () -> {}, names);
+	}
 }