Reestructura carpetes: src->source, third_party->source/external, shaders->data/shaders

data/shaders/just_another_cube/just_another_cube.frag.msl

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+#include <metal_stdlib>
+using namespace metal;
+
+// Just Another Cube — mrange
+// MSL port of just_another_cube.vk.glsl. The Shadertoy original uses
+// mutable file-scope globals; in MSL we pass them by reference.
+
+struct ShadertoyUBO {
+    float iTime;
+    float2 iResolution;
+};
+
+struct PassthroughVOut {
+    float4 pos [[position]];
+    float2 uv;
+};
+
+constant float M = 1e-3;
+
+static float D(float3 p,
+               thread float2x2& R,
+               thread float& d,
+               thread float& G) {
+    p.xy = p.xy * R;
+    p.xz = p.xz * R;
+
+    float3 S = sin(123.0 * p);
+
+    float shell = abs(length(p) - 0.6);
+    p *= p * p * p;
+    d = pow(dot(p, p), 0.125) - 0.5
+        - pow(1.0 + S.x * S.y * S.z, 8.0) / 1e5;
+
+    G = min(G, max(shell, d));
+
+    return d;
+}
+
+fragment float4 just_another_cube_fs(PassthroughVOut in [[stage_in]],
+                                      constant ShadertoyUBO& U [[buffer(0)]]) {
+    float2 C = in.uv * U.iResolution;
+
+    float2x2 R;
+    float d = 1.0, z = 0.0, G = 9.0;
+
+    float3 r = float3(U.iResolution, U.iResolution.y);
+    float3 I = normalize(float3(C - 0.5 * r.xy, r.y));
+    float3 B = float3(1, 2, 9) * M;
+    float3 p = float3(0.0);
+    float3 O = float3(0.0);
+
+    {
+        float4 cs = cos(0.3 * U.iTime + float4(0, 11, 33, 0));
+        R = float2x2(cs.x, cs.y, cs.z, cs.w);
+    }
+
+    for (; z < 9.0 && d > M; z += D(p, R, d, G)) {
+        p = z * I;
+        p.z -= 2.0;
+    }
+
+    if (z < 9.0) {
+        for (int i = 0; i < 3; ) {
+            r = float3(0.0);
+            r[i] = M;
+            O[i++] = D(p + r, R, d, G) - D(p - r, R, d, G);
+        }
+
+        O = normalize(O);
+        z = 1.0 + dot(O, I);
+
+        r = reflect(I, O);
+
+        C = (p + r * (5.0 - p.y) / abs(r.y)).xz;
+
+        float3 colorTerm;
+        if (r.y > 0.0) {
+            d = sqrt(length(C * C)) + 1.0;
+            colorTerm = 5e2 * smoothstep(5.0, 4.0, d) * d * B;
+        } else {
+            colorTerm = exp(-2.0 * length(C)) * (B / M - 1.0);
+        }
+
+        O = z * z * colorTerm + pow(1.0 + O.y, 5.0) * B;
+    }
+
+    float4 result = sqrt(float4(O + B / G, O.x + B.x / G));
+    return result;
+}

data/shaders/just_another_cube/just_another_cube.gl.glsl

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+// Name: Just Another Cube
+// Author: mrange
+// URL: https://www.shadertoy.com/view/3XdXRr
+#version 330 core
+precision highp float;
+
+out vec4 FragColor;
+in vec2 vUV;
+uniform vec2 iResolution;
+uniform float iTime;
+
+// CC0: Just another cube
+// Glowtracers are great for compact coding, but I wanted to see how much
+// I could squeeze a more normal raymarcher in terms of characters used.
+
+// Twigl: https://twigl.app?ol=true&ss=-OW-y9xgRgWubwKcn0Nd
+
+// == Globals ==
+// Single-letter variable names are used to save characters (code golfing).
+mat2 R;    // A 2D rotation matrix, calculated once per frame in mainImage and used by D.
+float d=1. // Stores the most recent distance to the scene from the ray's position.
+    , z=0. // Stores the total distance traveled along the ray (initialized to avoid undefined behavior)
+    , G=9. // "Glow" variable. Tracks the closest the ray comes to the object (for volumetric glow effect).
+    , M=1e-3
+    ;
+// == Distance Function (SDF - Signed Distance Field) ==
+// This function calculates the shortest distance from a given point 'p' to the scene geometry.
+// A positive result means the point is outside an object, negative is inside, and zero is on the surface.
+// This is the core of "raymarching", as it tells us the largest safe step we can take along a ray.
+float D(vec3 p) {
+  // Apply two rotations to the point's coordinates. This twists the space the object
+  // exists in, making the simple cube shape appear more complex and animated.
+  p.xy *= R;
+  p.xz *= R;
+
+  // Create a higher-frequency version of the coordinate for detailed surface patterns.
+  vec3 S = sin(123.*p);
+
+  // This creates a volumetric glow effect by tracking the minimum distance
+  // to either the existing glow value or a glowing shell around the object.
+  G = min(
+      G
+      // The glowing shell
+    , max(
+        abs(length(p)-.6)
+        // The main object distance calculation:
+        // 1. A superquadric (rounded cube shape) is created using an L8-norm.
+        // The expression `pow(dot(p=p*p*p*p,p),.125)` is a golfed version of
+        // `pow(pow(p.x,8)+pow(p.y,8)+pow(p.z,8), 1./8.)`.
+        // The `- .5` defines the object's size.
+      , d = pow(dot(p*=p*p*p,p),.125) - .5
+        // 2. Surface detail subtraction. This creates small surface variations
+        // using high-frequency sine waves for more appealing reflections.
+        - pow(1.+S.x*S.y*S.z,8.)/1e5
+      )
+    );
+
+  return d;
+}
+
+// == Main Render Function ==
+// This function is called for every pixel on the screen to determine its color.
+// 'o' is the final output color (rgba). 'C' is the input pixel coordinate (xy).
+void mainImage(out vec4 o, vec2 C) {
+  // Single-letter variable names are used to save characters (code golfing).
+  vec3  p  // The current point in 3D space along the ray.
+      , O  // Multi-purpose vector: color accumulator, then normal vector, then final color.
+      , r=vec3(iResolution.xy, iResolution.y)  // 'r' holds screen resolution, later re-used for the epsilon vector and reflection.
+        // 'I' is the Ray Direction vector. It's calculated once per pixel.
+        // This converts the 2D screen coordinate 'C' into a 3D direction, creating the camera perspective.
+      , I=normalize(vec3(C-.5*r.xy, r.y))
+        // Base glow color (dark bluish tint).
+      , B=vec3(1,2,9)*M
+      ;
+
+  // == Raymarching Loop ==
+  // This loop "marches" a ray from the camera out into the scene to find what it hits.
+  // It uses a golfed structure where the body of the loop updates the ray position 'p',
+  // and the "advancement" step moves the ray forward.
+  for(
+        // -- Initializer (runs once before the loop) --
+        // Calculate the rotation matrix for this frame based on time.
+        R = mat2(cos(.3*iTime+vec4(0,11,33,0)))
+    // -- Condition --
+    // Loop while total distance 'z' is less than 9 and we are not yet touching a surface (d > 1e-3).
+    ; z<9. && d > M
+    // -- Advancement --
+    // The ray advances by the safe distance 'd' returned by D(p).
+    // The result of D(p) is also assigned to the global 'd' inside the function.
+    ; z += D(p)
+    )
+    // -- Loop Body --
+    // Calculate the current position 'p' in world space.
+    // The camera starts at (0,0,-2) and points forward.
+    p = z*I
+  , p.z -= 2.
+  ;
+
+  // -- Hit Condition --
+  // If the loop finished because z exceeded the max distance, we hit nothing. Otherwise, we hit the surface.
+  if (z < 9.) {
+    // -- Calculate Surface Normal --
+    // Estimate the gradient ∇D at the hit point 'p' via central differences on the SDF D.
+    // We use ε = 1e-3 and loop over each axis (x, y, z):
+    //   • Zero r, then set r[i] = ε.
+    //   • Compute O[i] = D(p + r) – D(p – r).
+    // After the loop, O holds the unnormalized normal vector.
+    for (
+        int i=0               // axis index: 0→x, 1→y, 2→z (initialized to avoid warnings)
+      ; i < 3
+      ; O[i++] = D(p+r) - D(p-r)
+      )
+        r -= r                // clear r to vec3(0)
+      , r[i] = M              // set only the i-th component
+      ;
+
+    // -- Lighting and Shading --
+    // 'z' is re-purposed to store a fresnel factor (1 - cos(angle)) for edge brightness.
+    // `dot(O, I)` calculates how much the surface faces away from the camera.
+    // O is also normalized here to become a proper normal vector.
+    z = 1.+dot(O = normalize(O),I);
+
+    // 'r' is re-purposed to store the reflection vector.
+    r = reflect(I,O);
+
+    // Calculate a point 'C' along the reflection vector 'r' to sample a background color.
+    // For upward reflections (r.y > 0), this finds the intersection with the plane y=5.
+    C = (p+r*(5.-p.y)/abs(r.y)).xz;
+
+    // Calculate the final color 'O' of the hit point.
+    O =
+        // Multiply by the fresnel factor squared for stronger edge reflections.
+        z*z *
+        // Use a ternary operator to decide the color based on where the reflection ray goes.
+        (
+            // If the reflection vector points upward...
+            r.y>0.
+            // ...sample a procedural "sky" with a radial gradient and blue tint.
+          ? 5e2*smoothstep(5., 4., d = sqrt(length(C*C))+1.)*d*B
+            // ...otherwise, sample a "floor" with a deep blue exponential falloff.
+          : exp(-2.*length(C))*(B/M-1.)
+        )
+      // Add rim lighting (brighter on upward-facing surfaces).
+      + pow(1.+O.y,5.)*B
+      ;
+  }
+
+  // == Tonemapping & Output ==
+  // Apply final effects and map the High Dynamic Range (HDR) color to a displayable range.
+  // Add glow contribution: smaller G values (closer ray passes) create a brighter blue glow.
+  o = sqrt(O+B/G).xyzx;
+}
+
+void main() {
+    vec2 fragCoordPixels = vUV * iResolution;
+    vec4 outColor;
+    mainImage(outColor, fragCoordPixels);
+    FragColor = outColor;
+}

data/shaders/just_another_cube/just_another_cube.vk.glsl

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+#version 450
+
+// Name: Just Another Cube
+// Author: mrange
+// URL: https://www.shadertoy.com/view/3XdXRr
+// CC0: Just another cube
+
+layout(location = 0) in  vec2 vUV;
+layout(location = 0) out vec4 FragColor;
+
+layout(set = 3, binding = 0) uniform ShadertoyUBO {
+    float iTime;
+    vec2  iResolution;
+};
+
+mat2 R;
+float d = 1.;
+float z = 0.;
+float G = 9.;
+float M = 1e-3;
+
+float D(vec3 p) {
+    p.xy *= R;
+    p.xz *= R;
+
+    vec3 S = sin(123. * p);
+
+    G = min(
+        G,
+        max(
+            abs(length(p) - .6),
+            d = pow(dot(p *= p * p * p, p), .125) - .5
+                - pow(1. + S.x * S.y * S.z, 8.) / 1e5
+        )
+    );
+
+    return d;
+}
+
+void mainImage(out vec4 o, vec2 C) {
+    vec3 p,
+         O,
+         r = vec3(iResolution.xy, iResolution.y),
+         I = normalize(vec3(C - .5 * r.xy, r.y)),
+         B = vec3(1, 2, 9) * M;
+
+    for (
+        R = mat2(cos(.3 * iTime + vec4(0, 11, 33, 0)));
+        z < 9. && d > M;
+        z += D(p)
+    )
+        p = z * I,
+        p.z -= 2.;
+
+    O = vec3(0.0);
+
+    if (z < 9.) {
+        for (int i = 0; i < 3; ) {
+            r -= r;
+            r[i] = M;
+            O[i++] = D(p + r) - D(p - r);
+        }
+
+        z = 1. + dot(O = normalize(O), I);
+
+        r = reflect(I, O);
+
+        C = (p + r * (5. - p.y) / abs(r.y)).xz;
+
+        O =
+            z * z *
+            (
+                r.y > 0.
+                ? 5e2 * smoothstep(5., 4., d = sqrt(length(C * C)) + 1.) * d * B
+                : exp(-2. * length(C)) * (B / M - 1.)
+            )
+            + pow(1. + O.y, 5.) * B;
+    }
+
+    o = sqrt(O + B / G).xyzx;
+}
+
+void main() {
+    vec2 fragCoordPixels = vUV * iResolution;
+    vec4 outColor;
+    mainImage(outColor, fragCoordPixels);
+    FragColor = outColor;
+}

data/shaders/just_another_cube/meta.txt

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+Name: Just Another Cube
+Author: mrange