building a pure graphics pipeline version of this

slime_simulation_cs/shaders/decay_cs.glsl

@@ -0,0 +1,61 @@
+#[compute]
+#version 450
+
+// Invocations in the (x, y, z) dimension
+layout(local_size_x = 8, local_size_y = 8, local_size_z = 1) in;
+
+// Our textures.
+layout(r32f, set = 0, binding = 0) uniform restrict readonly image2D current_image;
+layout(r32f, set = 1, binding = 0) uniform restrict writeonly image2D output_image;
+
+// PushConstants
+layout(push_constant, std430) uniform Params {
+    ivec2 texture_size;
+    float decay_factor;
+    float dissipation_factor;
+} params;
+
+float get_dissipation_from(ivec2 uv) {
+    float v = imageLoad(current_image, uv).r;
+    // return v * params.dissipation_factor;
+    return v;
+}
+
+ivec2 loop_position(ivec2 pos) {
+    return pos % params.texture_size;
+}
+
+// The code we want to execute in each invocation
+void main() {
+
+    ivec2 uv = ivec2(gl_GlobalInvocationID.xy);
+
+    float current_sum = 0.0;
+    for (int i = -1; i <= 1; i++) {
+        for (int j = -1; j <= 1; j++) {
+            ivec2 kuv = loop_position(uv + ivec2(i,j));
+            current_sum += get_dissipation_from(kuv);
+        }
+    }
+    // ivec2 up_uv = loop_position(uv - ivec2(0, 1));
+    // ivec2 down_uv = loop_position(uv + ivec2(0, 1));
+    // ivec2 left_uv = loop_position(uv - ivec2(1, 0));
+    // ivec2 right_uv = loop_position(uv + ivec2(1, 0));
+
+
+    // Kill very old trails completely
+    // if (new_v < 0.001) {
+    //     new_v = 0;
+    // }
+
+    // new_v = clamp(new_v, 0, 1);
+
+    // This is good when not using trail for showind as is.
+    // https://github.com/Bleuje/physarum-36p/blob/main/bin/data/shaders/computeshader_deposit.glsl
+    current_sum = current_sum / pow(3.0, 2.0);
+
+    vec4 result = vec4(vec3(current_sum), 1.0);
+    imageStore(output_image, uv, result);
+
+
+}