export const screenVertexShader = `
varying vec2 vUv;

void main() {
    vUv = uv;
    gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
}
`;

export const screenFragmentShader = `
varying vec2 vUv;
uniform sampler2D videoTexture;
uniform float u_effect_type;     // 0: none, 1: warmup, 2: powerdown
uniform float u_effect_strength; // 0.0 to 1.0

void main() {
    vec2 centeredUv = vUv - 0.5;
    vec4 finalColor;

    if (u_effect_type < 0.5) { // No effect
        finalColor = texture2D(videoTexture, vUv);
    } else if (u_effect_type < 1.5) { // Warm-up effect
        // A bright dot expands to reveal the screen content
        float effectRadius = u_effect_strength * 0.75; // Max radius of 0.75 (sqrt(0.5*0.5 + 0.5*0.5))
        float distanceToCenter = length(centeredUv);
        
        // Smoothly transition the edge of the circle
        float vignette = smoothstep(effectRadius, effectRadius - 0.1, distanceToCenter);
        vec4 videoColor = texture2D(videoTexture, vUv);
        
        finalColor = videoColor * vignette * u_effect_strength; // Fade in brightness

    } else { // Power-down effect
        // The image collapses into a bright horizontal line and fades
        float collapseFactor = 1.0 - u_effect_strength;
        
        // Squeeze the UVs vertically
        vec2 squeezedUv = vec2(vUv.x, 0.5 + (vUv.y - 0.5) * collapseFactor);
        vec4 videoColor = texture2D(videoTexture, squeezedUv);
        
        // Create a bright glow where the line is
        float lineGlow = pow(1.0 - abs(centeredUv.y) / (0.5 * collapseFactor + 0.01), 20.0);
        
        finalColor = videoColor * collapseFactor + vec4(0.8, 0.9, 1.0, 1.0) * lineGlow * u_effect_strength;

    }

    gl_FragColor = finalColor;
}
`;