Move shader files to Shaders group

Terrain2/Shaders/Shaders.metal

@@ -0,0 +1,61 @@
+//
+//  Shaders.metal
+//  Terrain2
+//
+//  Created by Eryn Wells on 11/3/18.
+//  Copyright © 2018 Eryn Wells. All rights reserved.
+//
+
+// File for Metal kernel and shader functions
+
+#include <metal_stdlib>
+#include <simd/simd.h>
+
+// Including header shared between this Metal shader code and Swift/C code executing Metal API commands
+#import "ShaderTypes.h"
+
+using namespace metal;
+
+typedef struct
+{
+    float3 position [[attribute(VertexAttributePosition)]];
+    float2 texCoord [[attribute(VertexAttributeTexcoord)]];
+    uint2 gridCoord [[attribute(VertexAttributeGridCoord)]];
+} Vertex;
+
+typedef struct
+{
+    float4 position [[position]];
+    float2 texCoord;
+} ColorInOut;
+
+vertex ColorInOut vertexShader(Vertex in [[stage_in]],
+                               texture2d<float> heights [[texture(0)]],
+                               constant Uniforms & uniforms [[buffer(BufferIndexUniforms)]])
+{
+    constexpr sampler s(coord::normalized, address::clamp_to_zero, filter::linear);
+
+    ColorInOut out;
+
+    float4 height = heights.sample(s, in.texCoord);
+
+    // Replace the y coordinate with the height we read from the texture.
+    float4 position(in.position.x, height.r, in.position.z, 1.0);
+    out.position = uniforms.projectionMatrix * uniforms.modelViewMatrix * position;
+    out.texCoord = in.texCoord;
+
+    return out;
+}
+
+fragment float4 fragmentShader(ColorInOut in [[stage_in]],
+                               constant Uniforms & uniforms [[ buffer(BufferIndexUniforms) ]],
+                               texture2d<half> colorMap     [[ texture(TextureIndexColor) ]])
+{
+    constexpr sampler colorSampler(mip_filter::linear,
+                                   mag_filter::linear,
+                                   min_filter::linear);
+
+    half4 colorSample   = colorMap.sample(colorSampler, in.texCoord.xy);
+
+    return float4(1.0);
+}

Terrain2/Shaders/TerrainAlgorithms.metal

@@ -0,0 +1,62 @@
+//
+//  TerrainAlgorithms.metal
+//  Terrain2
+//
+//  Created by Eryn Wells on 11/4/18.
+//  Copyright © 2018 Eryn Wells. All rights reserved.
+//
+
+#include <metal_stdlib>
+#include <metal_types>
+#include "ShaderTypes.h"
+using namespace metal;
+
+/// A pseudo-random number generator providing several algorithms.
+/// - http://reedbeta.com/blog/quick-and-easy-gpu-random-numbers-in-d3d11/
+struct PRNG {
+    PRNG(uint seed) : mSeed(wangHash(seed)) { }
+
+    /// Generate a random unsigned integer using a linear congruential generator.
+    uint lcg() {
+        mSeed = 1664525 * mSeed + 1013904223;
+        return mSeed;
+    }
+
+    /// Generate a random unsigned integer using the Xorshift algorithm from George Marsaglia's paper.
+    uint xorShift() {
+        mSeed ^= (mSeed << 13);
+        mSeed ^= (mSeed >> 17);
+        mSeed ^= (mSeed << 5);
+        return mSeed;
+    }
+
+    uint wangHash(uint seed) {
+        seed = (seed ^ 61) ^ (seed >> 16);
+        seed *= 9;
+        seed = seed ^ (seed >> 4);
+        seed *= 0x27d4eb2d;
+        seed = seed ^ (seed >> 15);
+        return seed;
+    }
+
+private:
+    uint mSeed;
+};
+
+kernel void zeroKernel(texture2d<float, access::write> outTexture [[texture(GeneratorTextureIndexOut)]],
+                       uint2 tid [[thread_position_in_grid]])
+{
+    outTexture.write(0, tid);
+}
+
+#pragma mark - RandomAlgorithm
+
+kernel void randomKernel(texture2d<float, access::write> outTexture [[texture(GeneratorTextureIndexOut)]],
+                         constant RandomAlgorithmUniforms &uniforms [[buffer(0)]],
+                         uint2 tid [[thread_position_in_grid]])
+{
+    PRNG rng(uniforms.randoms[(tid.x * tid.y) % kRandomAlgorithmUniforms_RandomCount]);
+    uint r = rng.xorShift();
+    float x = float(r * (1.0 / float(UINT_MAX))) * 0.5f;
+    outTexture.write(x, tid);
+}