Pass through uniforms for normals, which means different colors for vertex and face normals!

Terrain2/Renderer.swift

@@ -38,6 +38,7 @@ class Renderer: NSObject, MTKViewDelegate {
     let regenerationSemaphore = DispatchSemaphore(value: 1)
 
     var geometryUniforms: PerFrameObject<Uniforms>
+    var normalUniforms: PerFrameObject<NormalUniforms>
 
     var lightsBuffer: MTLBuffer
     var lights: UnsafeMutablePointer<Light>
@@ -68,7 +69,8 @@ class Renderer: NSObject, MTKViewDelegate {
         self.device = metalKitView.device!
         self.commandQueue = self.device.makeCommandQueue()!
 
-        geometryUniforms = PerFrameObject(device: device, label: "Uniforms")
+        geometryUniforms = PerFrameObject(device: device, label: "Geometry Uniforms")
+        normalUniforms = PerFrameObject(device: device, label: "Normal Uniforms")
 
         metalKitView.depthStencilPixelFormat = MTLPixelFormat.depth32Float_stencil8
         metalKitView.colorPixelFormat = MTLPixelFormat.bgra8Unorm_srgb
@@ -212,6 +214,9 @@ class Renderer: NSObject, MTKViewDelegate {
 
         geometryUniforms.pointer[0].terrainDimensions = terrain.dimensions
         geometryUniforms.pointer[0].terrainSegments = terrain.segments
+
+        normalUniforms.pointer[0].faceNormalColor = simd_float3(0, 0.3, 1)
+        normalUniforms.pointer[0].vertexNormalColor = simd_float3(0, 1.0, 0)
     }
 
     func draw(in view: MTKView) {
@@ -237,6 +242,7 @@ class Renderer: NSObject, MTKViewDelegate {
             }
             
             geometryUniforms.updateOffsets()
+            normalUniforms.updateOffsets()
             
             self.updateGameState()
 
@@ -344,9 +350,16 @@ class Renderer: NSObject, MTKViewDelegate {
         let vertexBuffer = terrain.mesh.vertexBuffers[BufferIndex.meshPositions.rawValue]
         let normalBuffer = terrain.mesh.vertexBuffers[BufferIndex.normals.rawValue]
 
+        var type = NormalType.vertex.rawValue
+
         encoder.setVertexBuffer(vertexBuffer.buffer, offset: vertexBuffer.offset, index: NormalBufferIndex.points.rawValue)
         encoder.setVertexBuffer(normalBuffer.buffer, offset: normalBuffer.offset, index: NormalBufferIndex.normals.rawValue)
-        encoder.setVertexBuffer(geometryUniforms.buffer, offset: geometryUniforms.offset, index: NormalBufferIndex.uniforms.rawValue)
+        encoder.setVertexBuffer(geometryUniforms.buffer, offset: geometryUniforms.offset, index: NormalBufferIndex.geometryUniforms.rawValue)
+        encoder.setVertexBuffer(normalUniforms.buffer, offset: normalUniforms.offset, index: NormalBufferIndex.normalUniforms.rawValue)
+        encoder.setVertexBytes(&type, length: MemoryLayout<NSInteger>.size, index: NormalBufferIndex.type.rawValue)
+
+        encoder.setFragmentBuffer(normalUniforms.buffer, offset: normalUniforms.offset, index: NormalBufferIndex.normalUniforms.rawValue)
+
         encoder.drawPrimitives(type: .line, vertexStart: 0, vertexCount: 2, instanceCount: terrain.mesh.vertexCount)
 
         encoder.popDebugGroup()
@@ -359,9 +372,16 @@ class Renderer: NSObject, MTKViewDelegate {
         let faceNormalsBuffer = terrain.faceNormalsBuffer
         let instanceCount = 2 * Int(terrain.segments.x * terrain.segments.y)
 
+        var type = NormalType.face.rawValue
+
         encoder.setVertexBuffer(faceMidpointsBuffer, offset: 0, index: NormalBufferIndex.points.rawValue)
         encoder.setVertexBuffer(faceNormalsBuffer, offset: 0, index: NormalBufferIndex.normals.rawValue)
-        encoder.setVertexBuffer(geometryUniforms.buffer, offset: geometryUniforms.offset, index: NormalBufferIndex.uniforms.rawValue)
+        encoder.setVertexBuffer(geometryUniforms.buffer, offset: geometryUniforms.offset, index: NormalBufferIndex.geometryUniforms.rawValue)
+        encoder.setVertexBuffer(normalUniforms.buffer, offset: normalUniforms.offset, index: NormalBufferIndex.normalUniforms.rawValue)
+        encoder.setVertexBytes(&type, length: MemoryLayout<NSInteger>.size, index: NormalBufferIndex.type.rawValue)
+
+        encoder.setFragmentBuffer(normalUniforms.buffer, offset: normalUniforms.offset, index: NormalBufferIndex.normalUniforms.rawValue)
+
         encoder.drawPrimitives(type: .line, vertexStart: 0, vertexCount: 2, instanceCount: instanceCount)
 
         encoder.popDebugGroup()

Terrain2/Shaders/ShaderTypes.h

@@ -34,7 +34,9 @@ typedef NS_ENUM(NSInteger, BufferIndex) {
 typedef NS_ENUM(NSInteger, NormalBufferIndex) {
     NormalBufferIndexPoints = 0,
     NormalBufferIndexNormals = 1,
-    NormalBufferIndexUniforms = 2,
+    NormalBufferIndexGeometryUniforms = 2,
+    NormalBufferIndexNormalUniforms = 3,
+    NormalBufferIndexType = 4,
 };
 
 typedef NS_ENUM(NSInteger, VertexAttribute)
@@ -86,7 +88,7 @@ struct Material {
     float specularExponent;
 };
 
-typedef struct {
+struct Uniforms {
     matrix_float4x4 projectionMatrix;
     matrix_float4x4 modelViewMatrix;
     matrix_float3x3 normalMatrix;
@@ -97,7 +99,22 @@ typedef struct {
     simd_packed_float2 terrainDimensions;
     simd_packed_uint2 terrainSegments;
 #endif
-} Uniforms;
+};
+
+typedef NS_ENUM(NSInteger, NormalType) {
+    NormalTypeVertex = 1,
+    NormalTypeFace = 2,
+};
+
+struct NormalUniforms {
+#ifdef __METAL_VERSION__
+    simd::float3 vertexNormalColor;
+    simd::float3 faceNormalColor;
+#else
+    simd_float3 vertexNormalColor;
+    simd_float3 faceNormalColor;
+#endif
+};
 
 #endif /* ShaderTypes_h */
 

Terrain2/Shaders/Shaders.metal

@@ -94,22 +94,39 @@ fragment float4 fragmentShader(ColorInOut in [[stage_in]],
 
 #pragma mark - Normal Shaders
 
-vertex float4 normalVertexShader(constant packed_float3 *positions [[buffer(NormalBufferIndexPoints)]],
+struct NormalInOut {
-                                 constant packed_float3 *normals [[buffer(NormalBufferIndexNormals)]],
+    float4 position [[position]];
-                                 constant Uniforms &uniforms [[buffer(NormalBufferIndexUniforms)]],
+    float3 color;
-                                 uint instID [[instance_id]],
+};
-                                 uint vertID [[vertex_id]])
+
+vertex NormalInOut normalVertexShader(constant packed_float3 *positions [[buffer(NormalBufferIndexPoints)]],
+                                      constant packed_float3 *normals [[buffer(NormalBufferIndexNormals)]],
+                                      constant Uniforms &uniforms [[buffer(NormalBufferIndexGeometryUniforms)]],
+                                      constant NormalUniforms &normalUniforms [[buffer(NormalBufferIndexNormalUniforms)]],
+                                      constant NormalType &type [[buffer(NormalBufferIndexType)]],
+                                      uint instID [[instance_id]],
+                                      uint vertID [[vertex_id]])
 {
+    NormalInOut out;
     float3 v = positions[instID];
     if ( vertID == 1 )
     {
         v += 0.25 * normals[instID];
     }
-    float4 out = uniforms.projectionMatrix * uniforms.modelViewMatrix * float4(v, 1);
+    out.position = uniforms.projectionMatrix * uniforms.modelViewMatrix * float4(v, 1);
+
+    if (type == NormalTypeFace) {
+        out.color = normalUniforms.faceNormalColor;
+    } else {
+        out.color = normalUniforms.vertexNormalColor;
+    }
+
     return out;
 }
 
-fragment half4 normalFragmentShader()
+fragment float4 normalFragmentShader(NormalInOut in [[stage_in]],
+                                     constant Uniforms &uniforms [[buffer(NormalBufferIndexGeometryUniforms)]],
+                                     constant NormalUniforms &normalUniforms [[buffer(NormalBufferIndexNormalUniforms)]])
 {
-    return half4(0, 1, 0, 1);
+    return float4(in.color, 1.0);
 }