I keep getting error in when trying to install it in C3, "invalid json".
I have the following files in a zip, renamed to .c3addon
in the root directory.
lang/en-US.json
{
"languageTag": "en-US",
"fileDescription": "Strings for the 'Star Nebula Starfield' effect.",
"text": {
"effects": {
"StarNebulaFX": {
"name": "Star Nebula Starfield",
"description": "Generates a procedural 2D starfield with animated nebula clouds and twinkling stars.",
"parameters": {
"nebula-color-1": {
"name": "Nebula Color 1",
"desc": "First color for the nebula gradient."
},
"nebula-color-2": {
"name": "Nebula Color 2",
"desc": "Second color for the nebula gradient."
},
"nebula-scale": {
"name": "Nebula Scale",
"desc": "Size/zoom of nebula clouds. Smaller values = larger clouds."
},
"nebula-speed": {
"name": "Nebula Speed",
"desc": "Speed of nebula animation."
},
"star-density": {
"name": "Star Density",
"desc": "Controls the number of stars."
},
"star-twinkle-speed": {
"name": "Star Twinkle Speed",
"desc": "Speed of star twinkling."
},
"effect-brightness": {
"name": "Effect Brightness",
"desc": "Overall brightness of the generated effect."
}
}
}
}
}
}
addon.json file
{
"is-c3-addon": true,
"type": "effect",
"name": "Star Nebula Starfield",
"id": "StarNebulaFX",
"version": "1.0.0.0",
"author": "Your Name",
"website": "",
"documentation": "",
"description": "Generates a procedural 2D starfield with animated nebula clouds and twinkling stars.",
"file-list": [
"lang/en-US.json",
"addon.json",
"StarNebula.fx"
],
"category": "visual",
"blends-background": false,
"cross-sampling": false,
"preserves-opaqueness": false,
"animated": true,
"extend-box": {
"horizontal": 0,
"vertical": 0
},
"parameters": [
{
"id": "nebula-color-1",
"type": "color",
"initial-value": [0.1, 0.0, 0.2],
"uniform": "uNebulaColor1"
},
{
"id": "nebula-color-2",
"type": "color",
"initial-value": [0.0, 0.2, 0.4],
"uniform": "uNebulaColor2"
},
{
"id": "nebula-scale",
"type": "float",
"initial-value": 3.0,
"minimum": 0.1,
"maximum": 10.0,
"uniform": "uNebulaScale"
},
{
"id": "nebula-speed",
"type": "float",
"initial-value": 0.5,
"minimum": 0.0,
"maximum": 5.0,
"uniform": "uNebulaSpeed"
},
{
"id": "star-density",
"type": "percent",
"initial-value": 0.5,
"uniform": "uStarDensity"
},
{
"id": "star-twinkle-speed",
"type": "float",
"initial-value": 1.0,
"minimum": 0.0,
"maximum": 10.0,
"uniform": "uStarTwinkleSpeed"
},
{
"id": "effect-brightness",
"type": "percent",
"initial-value": 1.0,
"uniform": "uEffectBrightness"
}
]
}
StarNebula.fx file
// Content for StarNebula.fx
varying mediump vec2 vTex;
// Provided uniforms (samplerFront is common without effect.js, uTime if animated=true)
uniform sampler2D samplerFront;
uniform mediump float uTime;
// Custom uniforms mapped from parameters in addon.json
uniform mediump vec3 uNebulaColor1;
uniform mediump vec3 uNebulaColor2;
uniform mediump float uNebulaScale;
uniform mediump float uNebulaSpeed;
uniform mediump float uStarDensity; // Received as 0.0-1.0
uniform mediump float uStarTwinkleSpeed;
uniform mediump float uEffectBrightness; // Received as 0.0-1.0
// --- Noise Functions ---
// Simple pseudo-random number generator
mediump float random (mediump vec2 st) {
return fract(sin(dot(st.xy, vec2(12.9898,78.233))) * 43758.5453123);
}
// Smooth noise function (Value Noise)
mediump float noise (mediump vec2 st) {
mediump vec2 i = floor(st);
mediump vec2 f = fract(st);
mediump vec2 u = f*f*(3.0-2.0*f); // Smoothstep calculation
// Four corners in 2D of a tile
mediump float a = random(i);
mediump float b = random(i + vec2(1.0, 0.0));
mediump float c = random(i + vec2(0.0, 1.0));
mediump float d = random(i + vec2(1.0, 1.0));
return mix(a, b, u.x) + (c - a)* u.y * (1.0 - u.x) + (d - b) * u.x * u.y;
}
// Fractional Brownian Motion (simple version)
mediump float fbm (mediump vec2 st) {
mediump float value = 0.0;
mediump float amplitude = 0.5;
// Loop for multiple octaves of noise
for (int i = 0; i < 4; i++) {
value += amplitude * noise(st);
st *= 2.0;
amplitude *= 0.5;
}
return value;
}
// --- Main Shader Logic ---
void main(void)
{
// --- Nebula Calculation ---
mediump vec2 nebulaCoord = vTex * uNebulaScale;
nebulaCoord += vec2(uTime * uNebulaSpeed * 0.1, uTime * uNebulaSpeed * 0.05);
mediump float nebulaValue = fbm(nebulaCoord);
nebulaValue = smoothstep(0.2, 0.7, nebulaValue);
mediump vec3 nebulaColor = mix(uNebulaColor1, uNebulaColor2, nebulaValue);
// --- Star Calculation ---
mediump vec2 starCoord = vTex * 30.0;
mediump float starNoise = random(starCoord);
// Map density (0-1) to threshold (e.g., 1.0 - 0.985)
mediump float densityThreshold = 1.0 - (uStarDensity * 0.015);
mediump float stars = pow(starNoise, 50.0); // Sharpen noise peaks
stars = step(densityThreshold, stars); // Create sparse points
// Twinkling
mediump float twinkleValue = noise(vTex * 10.0 + uTime * uStarTwinkleSpeed * 0.5);
twinkleValue = smoothstep(0.3, 0.7, twinkleValue) * 0.5 + 0.5; // Varying intensity (0.5 to 1.0)
stars *= twinkleValue;
// --- Combine and Output ---
mediump vec3 finalColor = (nebulaColor + vec3(stars)) * uEffectBrightness;
// Output final color, assume opaque
gl_FragColor = vec4(finalColor, 1.0);
}
I checked with online json validator and it seems valid.
Thanks.