Added negative promp

swift/StableDiffusion/pipeline/StableDiffusionPipeline.swift

@@ -117,6 +117,7 @@ public struct StableDiffusionPipeline: ResourceManaging {
     ///            The images will be nil if safety checks were performed and found the result to be un-safe
     public func generateImages(
         prompt: String,
+        negativePrompt: String = "",
         imageCount: Int = 1,
         stepCount: Int = 50,
         seed: Int = 0,
@@ -127,7 +128,7 @@ public struct StableDiffusionPipeline: ResourceManaging {
 
         // Encode the input prompt as well as a blank unconditioned input
         let promptEmbedding = try textEncoder.encode(prompt)
-        let blankEmbedding = try textEncoder.encode("")
+        let negativePromptEmbedding = try textEncoder.encode(negativePrompt)
 
         if reduceMemory {
             textEncoder.unloadResources()
@@ -135,7 +136,7 @@ public struct StableDiffusionPipeline: ResourceManaging {
 
         // Convert to Unet hidden state representation
         let concatEmbedding = MLShapedArray<Float32>(
-            concatenating: [blankEmbedding, promptEmbedding],
+            concatenating: [negativePromptEmbedding, promptEmbedding],
             alongAxis: 0
         )
 
@@ -186,6 +187,7 @@ public struct StableDiffusionPipeline: ResourceManaging {
             let progress = Progress(
                 pipeline: self,
                 prompt: prompt,
+                negativePromp: negativePrompt,
                 step: step,
                 stepCount: stepCount,
                 currentLatentSamples: latents,
@@ -292,6 +294,7 @@ extension StableDiffusionPipeline {
     public struct Progress {
         public let pipeline: StableDiffusionPipeline
         public let prompt: String
+        public let negativePromp: String
         public let step: Int
         public let stepCount: Int
         public let currentLatentSamples: [MLShapedArray<Float32>]

swift/StableDiffusionCLI/main.swift

@@ -19,6 +19,9 @@ struct StableDiffusionSample: ParsableCommand {
     @Argument(help: "Input string prompt")
     var prompt: String
 
+    @Option(help: "Input string negative prompt")
+    var negativePrompt: String
+
     @Option(
         help: ArgumentHelp(
             "Path to stable diffusion resources.",
@@ -85,6 +88,7 @@ struct StableDiffusionSample: ParsableCommand {
 
         let images = try pipeline.generateImages(
             prompt: prompt,
+            negativePrompt: negativePrompt,
             imageCount: imageCount,
             stepCount: stepCount,
             seed: seed,