Meatball

gistfile1.txt

val MetaballShader = """
    uniform float2 resolution;
    uniform shader image;
    uniform float time;
    
    half4 main(vec2 fragCoord) {
        float2 uv = fragCoord/resolution.xy;
        float aspect = resolution.x/resolution.y;
        
        float2 adjustedUV = float2(uv.x * aspect - aspect*0.5, uv.y - 0.5);
        
       
        float movement = 0.15 * sin(time);
        
      
        float d1 = length(adjustedUV - float2(movement, 0.0));
        float d2 = length(adjustedUV + float2(movement, 0.0));
        
     
        float metaball = 1.0/(d1*20.0) + 1.0/(d2*20.0);
        metaball = metaball * 0.5;  
        
        float final = smoothstep(0.5, 0.5, metaball);
        
        return half4(final, final, final, 1);
    }
""".trimIndent()

@Preview
@RequiresApi(Build.VERSION_CODES.TIRAMISU)
@Composable
fun Metaball() {
    val shader = remember { RuntimeShader(MetaballShader) }
    var time by remember { mutableStateOf(0f) }

    LaunchedEffect(Unit) {
        while(true) {
            withFrameNanos { frameTime ->
                time = (frameTime / 1_000_000_000f)  // 转换纳秒到秒
            }
        }
    }

    Column(
        modifier = Modifier
            .fillMaxSize()
            .background(Color.DarkGray)
            .padding(16.dp)
    ) {
        Box(
            modifier = Modifier
                .weight(1f)
                .fillMaxWidth()
                .onSizeChanged { size ->
                    shader.setFloatUniform(
                        "resolution",
                        size.width.toFloat(),
                        size.height.toFloat()
                    )
                }
                .graphicsLayer {
                    renderEffect = RenderEffect
                        .createRuntimeShaderEffect(
                            shader.apply {
                                setFloatUniform("time", time)
                            },
                            "image"
                        )
                        .asComposeRenderEffect()
                }
                .background(Color.White)
        )
    }
}