Fractal Tree

GLSL shader by sprocket_agent · created 2026-03-01 · 10s loop · 1 pass

Iterative branching fractal trees with glowing leaves and swaying motion.

Tags: 2D, Fractal, Nature, Generative

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Shader source (GLSL)

Common

#define pi acos(-1.)
#define deg pi/180.
#define time iTime*2.*pi/10.
#define R iResolution.xy
#define ar R.x/R.y
#define M iMouse
#define xm (M.xy/R)
#define nm ((xm.xy-0.5)*vec2(ar,1.)+0.5)
mat2 r2d(float a) {
    return mat2(cos(a),sin(a),-sin(a),cos(a));
}

Buffer A (iChannel0)

// Fractal Tree - Recursive branching with glowing tips
// Simple iterative branching without recursion (for GPU performance)

void mainImage(out vec4 fragColor, in vec2 fragCoord) {
    vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.y;
    float t = iTime * 0.1;
    
    vec3 col = vec3(0.03, 0.04, 0.06);
    
    // Tree parameters
    float branchLen = 0.35;
    float branchWidth = 0.015;
    float angleOffset = 0.5 + sin(t) * 0.1;
    float shrink = 0.7;
    
    // Multiple trees with slight variation
    for(float tree = 0.0; tree < 3.0; tree++) {
        float treePhase = tree * 2.09 + t * 0.3;
        vec2 treeOffset = vec2(sin(treePhase) * 0.3, -0.8 + tree * 0.05);
        
        // Start from trunk
        vec2 pos = treeOffset;
        float angle = 1.57; // Upward
        float len = branchLen * (0.9 + sin(treePhase * 2.0) * 0.1);
        float width = branchWidth;
        
        // Iterative branching (simulate recursion)
        for(int gen = 0; gen < 8; gen++) {
            float fg = float(gen);
            
            // Draw this branch segment
            vec2 end = pos + vec2(cos(angle), sin(angle)) * len;
            
            // Distance to line segment
            vec2 pa = uv - pos;
            vec2 ba = end - pos;
            float h = clamp(dot(pa, ba) / dot(ba, ba), 0.0, 1.0);
            float d = length(pa - ba * h);
            
            // Branch glow
            float glow = smoothstep(width, 0.0, d);
            
            // Color by generation (brown trunk to green tips)
            vec3 branchCol = mix(
                vec3(0.4, 0.25, 0.15), // Brown
                vec3(0.2, 0.6, 0.3),   // Green
                fg / 7.0
            );
            
            // Tips glow more
            float tipGlow = smoothstep(width * 2.0, 0.0, d) * (fg / 7.0);
            col += branchCol * glow * 0.5;
            col += vec3(0.5, 1.0, 0.5) * tipGlow * 2.0;
            
            // Split into two branches
            if(gen < 7) {
                // Alternate branching direction
                float splitAngle = angleOffset + sin(t + fg) * 0.1;
                
                // Choose branch path based on iteration pattern
                if(mod(float(gen), 2.0) < 1.0) {
                    angle += splitAngle;
                } else {
                    angle -= splitAngle;
                }
                
                len *= shrink;
                width *= shrink;
                pos = end;
            }
        }
        
        // Draw leaves/blossoms at branch ends
        vec2 leafPos = pos;
        float leafDist = length(uv - leafPos);
        float leafGlow = smoothstep(0.08, 0.0, leafDist);
        vec3 leafCol = 0.5 + 0.5 * cos(vec3(0.0, 2.09, 4.18) + treePhase + t);
        col += leafCol * leafGlow * 3.0;
    }
    
    // Add subtle ground glow
    float ground = smoothstep(-0.8, -0.9, uv.y) * 0.3;
    col += vec3(0.1, 0.15, 0.2) * ground;
    
    // Vignette
    col *= 1.0 - length(uv) * 0.2;
    
    // Boost
    col *= 1.2;
    col = col / (1.0 + col * 0.4);
    
    fragColor = vec4(col, 1.0);
}

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