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import jfaInitShader from "@/lib/shaders/jfa-init.frag.glsl";
import jfaStepShader from "@/lib/shaders/jfa-step.frag.glsl";
import {
compileProgram,
createFramebufferTexture,
setUniforms,
drawFullscreenQuad,
} from "./webgl-utils";
interface FBPair {
texture: WebGLTexture;
framebuffer: WebGLFramebuffer;
}
function runPass({
context,
program,
inputTexture,
target,
width,
height,
uniforms,
extraBindings,
}: {
context: WebGLRenderingContext;
program: WebGLProgram;
inputTexture: WebGLTexture;
target: WebGLFramebuffer | null;
width: number;
height: number;
uniforms: Record<string, number | number[]>;
extraBindings?: Array<{ unit: number; texture: WebGLTexture; name: string }>;
}): void {
context.bindFramebuffer(context.FRAMEBUFFER, target);
// biome-ignore lint/correctness/useHookAtTopLevel: WebGL API method, not a React hook
context.useProgram(program);
context.activeTexture(context.TEXTURE0);
context.bindTexture(context.TEXTURE_2D, inputTexture);
const uTexLoc = context.getUniformLocation(program, "u_texture");
if (uTexLoc) context.uniform1i(uTexLoc, 0);
if (extraBindings) {
for (const binding of extraBindings) {
context.activeTexture(context.TEXTURE0 + binding.unit);
context.bindTexture(context.TEXTURE_2D, binding.texture);
const loc = context.getUniformLocation(program, binding.name);
if (loc) context.uniform1i(loc, binding.unit);
}
}
setUniforms({
context,
program,
uniforms: { ...uniforms, u_resolution: [width, height] },
});
drawFullscreenQuad({ context, program, width, height });
}
function runJFA({
context,
programCache,
sourceTexture,
width,
height,
isInverted,
}: {
context: WebGLRenderingContext;
programCache: Map<string, WebGLProgram>;
sourceTexture: WebGLTexture;
width: number;
height: number;
isInverted: boolean;
}): {
resultTexture: WebGLTexture;
resultFB: WebGLFramebuffer;
tempFBs: FBPair[];
} {
const numSteps = Math.ceil(Math.log2(Math.max(width, height)));
const fbA = createFramebufferTexture({ context, width, height });
const fbB = createFramebufferTexture({ context, width, height });
const initProgram = compileProgram({
context,
fragmentShaderSource: jfaInitShader,
programCache,
});
runPass({
context,
program: initProgram,
inputTexture: sourceTexture,
target: fbA.framebuffer,
width,
height,
uniforms: { u_invert: isInverted ? 1.0 : 0.0 },
});
const stepProgram = compileProgram({
context,
fragmentShaderSource: jfaStepShader,
programCache,
});
let readFB = fbA;
let writeFB = fbB;
for (let i = numSteps - 1; i >= 0; i--) {
const stepSize = 2 ** i;
runPass({
context,
program: stepProgram,
inputTexture: readFB.texture,
target: writeFB.framebuffer,
width,
height,
uniforms: { u_step_size: stepSize },
});
const tmp = readFB;
readFB = writeFB;
writeFB = tmp;
}
return {
resultTexture: readFB.texture,
resultFB: readFB.framebuffer,
tempFBs: [writeFB],
};
}
function cleanupJFAResult({
context,
result,
}: {
context: WebGLRenderingContext;
result: {
resultTexture: WebGLTexture;
resultFB: WebGLFramebuffer;
tempFBs: FBPair[];
};
}): void {
context.deleteTexture(result.resultTexture);
context.deleteFramebuffer(result.resultFB);
for (const fb of result.tempFBs) {
context.deleteTexture(fb.texture);
context.deleteFramebuffer(fb.framebuffer);
}
}
export { runPass };
export function computeSignedDistanceField({
context,
programCache,
sourceTexture,
width,
height,
}: {
context: WebGLRenderingContext;
programCache: Map<string, WebGLProgram>;
sourceTexture: WebGLTexture;
width: number;
height: number;
}): {
insideTexture: WebGLTexture;
outsideTexture: WebGLTexture;
cleanup: () => void;
} {
const inside = runJFA({
context,
programCache,
sourceTexture,
width,
height,
isInverted: false,
});
const outside = runJFA({
context,
programCache,
sourceTexture,
width,
height,
isInverted: true,
});
return {
insideTexture: inside.resultTexture,
outsideTexture: outside.resultTexture,
cleanup: () => {
cleanupJFAResult({ context, result: inside });
cleanupJFAResult({ context, result: outside });
},
};
}
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