rcrnstn found a way to make the shaders work under MESA by forcing the version number to 120 and no default params in functions.

assets/shaders/flame_trash.frag

@@ -1,8 +1,10 @@
+#version 120
 uniform vec2 u_resolution;
 uniform float u_time;
 uniform sampler2D source;
 uniform float u_mouse;
 uniform float value = 0.2;
+uniform int octaves=8;
 
 float random (in vec2 st) {
     return fract(sin(dot(st.xy,
@@ -26,7 +28,7 @@ float noise(in vec2 st) {
     (d - b) * u.x * u.y;
 }
 
-float fbm(in vec2 st, int octaves=8) {
+float fbm(in vec2 st) {
   float v = 0.0;
   float a = 0.5;
   vec2 shift = vec2(100.0);
@@ -47,7 +49,7 @@ void main() {
   vec3 color = vec3(0.0);
 
   float speed = u_time * 10.0;
-  float value = cos(u_time) * cos(u_time);
+  float value = 0.8; // cos(u_time) * cos(u_time);
 
   vec2 q = vec2(0.0);
   q.x = fbm(st + 0.00 * speed);

assets/shaders/lightning_attack.frag

@@ -1,8 +1,10 @@
+#version 120
 uniform vec2 u_resolution;
 uniform float u_time;
 uniform sampler2D source;
 uniform float u_mouse;
 uniform float value = 0.2;
+uniform int octaves=8;
 
 float random (in vec2 st) {
     return fract(sin(dot(st.xy,
@@ -26,7 +28,7 @@ float noise(in vec2 st) {
     (d - b) * u.x * u.y;
 }
 
-float fbm(in vec2 st, int octaves=8) {
+float fbm(in vec2 st) {
   float v = 0.0;
   float a = 0.5;
   vec2 shift = vec2(100.0);