fix incorrect color scale

Author: mourner

src/index.js

@@ -15,8 +15,8 @@ var defaultRampColors = {
     0.2: '#abdda4',
     0.3: '#e6f598',
     0.4: '#fee08b',
-    0.6: '#fdae61',
-    0.9: '#f46d43',
+    0.5: '#fdae61',
+    0.6: '#f46d43',
     1.0: '#d53e4f'
 };
 
@@ -61,7 +61,7 @@ export function init(gl, windData, windImage, particleStateTextureSize) {
         util.bindFramebuffer(gl, framebuffer, screenTexture);
         gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
 
-        drawTexture(backgroundTexture, 0.996);
+        drawTexture(backgroundTexture, 0.999);
         drawParticles();
 
         util.bindFramebuffer(gl, null);

src/shaders/draw.frag.glsl

@@ -11,8 +11,8 @@ void main() {
     vec2 velocity = u_wind_min + (u_wind_max - u_wind_min) * texture2D(u_wind, v_particle_pos).rg;
     float speed_t = length(velocity) / length(u_wind_max);
 
-    float x = mod(512.0 * speed_t, 16.0) / 16.0;
-    float y = floor(512.0 * speed_t / 16.0) / 16.0;
+    float x = fract(16.0 * speed_t);
+    float y = floor(16.0 * speed_t) / 16.0;
 
     gl_FragColor = texture2D(u_color_ramp, vec2(x, y));
 }

src/shaders/update.frag.glsl

@@ -41,7 +41,7 @@ void main() {
     vec2 seed = (particle_pos + v_position) * u_rand_seed;
 
     particle_pos = rand(seed) < 0.997 - speed_t * 0.01
-        ? mod(1.0 + particle_pos + vec2(dx, dy) * 0.00002, 1.0)
+        ? fract(1.0 + particle_pos + vec2(dx, dy) * 0.00002)
         : vec2(rand(seed + 1.3), rand(seed + 2.1));
 
     gl_FragColor = vec4(encode(particle_pos.x), encode(particle_pos.y));