first steps toward manipulating planet vertices

src/EngineSharp.Core/EngineSharp.Core/Rendering/ComputeShader.cs

@@ -5,6 +5,7 @@ using Silk.NET.OpenGL;
 namespace EngineSharp.Core.Rendering;
 
 // https://learnopengl.com/Guest-Articles/2022/Compute-Shaders/Introduction
+// USE THIS FOR SENDING DATA TO SHADER FOR MANIPULATION: https://wikis.khronos.org/opengl/Buffer_Object#Creation
 public class ComputeShader
 {
     private readonly string _computeShaderCode;

src/EngineSharp/assets/shaders/planet_generator.comp

@@ -1,5 +1,124 @@
 #version 430 core
 
-void main() {
+layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
 
+layout(std430, binding = 0) buffer verticesArray {
+    vec3 vertices[];
+};
+
+vec3 mod289(vec3 x)
+{
+    return x - floor(x / 289.0) * 289.0;
+}
+
+vec4 mod289(vec4 x)
+{
+    return x - floor(x / 289.0) * 289.0;
+}
+
+vec4 permute(vec4 x)
+{
+    return mod289((x * 34.0 + 1.0) * x);
+}
+
+vec4 taylorInvSqrt(vec4 r)
+{
+    return 1.79284291400159 - r * 0.85373472095314;
+}
+
+float snoise(vec3 v)
+{
+    const vec2 C = vec2(1.0 / 6.0, 1.0 / 3.0);
+
+    // First corner
+    vec3 i  = floor(v + dot(v, C.yyy));
+    vec3 x0 = v   - i + dot(i, C.xxx);
+
+    // Other corners
+    vec3 g = step(x0.yzx, x0.xyz);
+    vec3 l = 1.0 - g;
+    vec3 i1 = min(g.xyz, l.zxy);
+    vec3 i2 = max(g.xyz, l.zxy);
+
+    // x1 = x0 - i1  + 1.0 * C.xxx;
+    // x2 = x0 - i2  + 2.0 * C.xxx;
+    // x3 = x0 - 1.0 + 3.0 * C.xxx;
+    vec3 x1 = x0 - i1 + C.xxx;
+    vec3 x2 = x0 - i2 + C.yyy;
+    vec3 x3 = x0 - 0.5;
+
+    // Permutations
+    i = mod289(i); // Avoid truncation effects in permutation
+    vec4 p =
+    permute(permute(permute(i.z + vec4(0.0, i1.z, i2.z, 1.0))
+                    + i.y + vec4(0.0, i1.y, i2.y, 1.0))
+            + i.x + vec4(0.0, i1.x, i2.x, 1.0));
+
+    // Gradients: 7x7 points over a square, mapped onto an octahedron.
+    // The ring size 17*17 = 289 is close to a multiple of 49 (49*6 = 294)
+    vec4 j = p - 49.0 * floor(p / 49.0);  // mod(p,7*7)
+
+    vec4 x_ = floor(j / 7.0);
+    vec4 y_ = floor(j - 7.0 * x_);  // mod(j,N)
+
+    vec4 x = (x_ * 2.0 + 0.5) / 7.0 - 1.0;
+    vec4 y = (y_ * 2.0 + 0.5) / 7.0 - 1.0;
+
+    vec4 h = 1.0 - abs(x) - abs(y);
+
+    vec4 b0 = vec4(x.xy, y.xy);
+    vec4 b1 = vec4(x.zw, y.zw);
+
+    //vec4 s0 = vec4(lessThan(b0, 0.0)) * 2.0 - 1.0;
+    //vec4 s1 = vec4(lessThan(b1, 0.0)) * 2.0 - 1.0;
+    vec4 s0 = floor(b0) * 2.0 + 1.0;
+    vec4 s1 = floor(b1) * 2.0 + 1.0;
+    vec4 sh = -step(h, 0.0);
+
+    vec4 a0 = b0.xzyw + s0.xzyw * sh.xxyy;
+    vec4 a1 = b1.xzyw + s1.xzyw * sh.zzww;
+
+    vec3 g0 = vec3(a0.xy, h.x);
+    vec3 g1 = vec3(a0.zw, h.y);
+    vec3 g2 = vec3(a1.xy, h.z);
+    vec3 g3 = vec3(a1.zw, h.w);
+
+    // Normalise gradients
+    vec4 norm = taylorInvSqrt(vec4(dot(g0, g0), dot(g1, g1), dot(g2, g2), dot(g3, g3)));
+    g0 *= norm.x;
+    g1 *= norm.y;
+    g2 *= norm.z;
+    g3 *= norm.w;
+
+    // Mix final noise value
+    vec4 m = max(0.6 - vec4(dot(x0, x0), dot(x1, x1), dot(x2, x2), dot(x3, x3)), 0.0);
+    m = m * m;
+    m = m * m;
+
+    vec4 px = vec4(dot(x0, g0), dot(x1, g1), dot(x2, g2), dot(x3, g3));
+    return 42.0 * dot(m, px);
+}
+
+float simpleNoise(float3 pos) {
+    const float scale = 1;
+    const float multiplier = 1;
+
+    return simpleNoise(pos, scale, multiplier);
+}
+
+void main() {
+    uint idx = gl_GlobalInvocationID.x;
+    if (idx >= vertices.length()) // If out of range, return 
+    {
+        return;
+    }
+
+    vec3 pos = vertices[idx];
+
+    float noise = simpleNoise(pos);
+    noise = smoothMax(noise, -oceanSettings.x, oceanSettings.y); // oceanDepth and smoothing
+
+    float finalHeight = 1 + noise * 0.01;
+
+    vertices[idx] = pos * finalHeight;
 }