@luma.gl/shadertools/dist/modules/math/fp64/fp64-arithmetic-glsl.d.ts

Shader module system for luma.gl

export declare const fp64arithmeticShader = "\nuniform fp64arithmeticUniforms {\n  uniform float ONE;\n} fp64;\n\n/*\nAbout LUMA_FP64_CODE_ELIMINATION_WORKAROUND\n\nThe purpose of this workaround is to prevent shader compilers from\noptimizing away necessary arithmetic operations by swapping their sequences\nor transform the equation to some 'equivalent' form.\n\nThe method is to multiply an artifical variable, ONE, which will be known to\nthe compiler to be 1 only at runtime. The whole expression is then represented\nas a polynomial with respective to ONE. In the coefficients of all terms, only one a\nand one b should appear\n\nerr = (a + b) * ONE^6 - a * ONE^5 - (a + b) * ONE^4 + a * ONE^3 - b - (a + b) * ONE^2 + a * ONE\n*/\n\n// Divide float number to high and low floats to extend fraction bits\nvec2 split(float a) {\n  const float SPLIT = 4097.0;\n  float t = a * SPLIT;\n#if defined(LUMA_FP64_CODE_ELIMINATION_WORKAROUND)\n  float a_hi = t * fp64.ONE - (t - a);\n  float a_lo = a * fp64.ONE - a_hi;\n#else\n  float a_hi = t - (t - a);\n  float a_lo = a - a_hi;\n#endif\n  return vec2(a_hi, a_lo);\n}\n\n// Divide float number again when high float uses too many fraction bits\nvec2 split2(vec2 a) {\n  vec2 b = split(a.x);\n  b.y += a.y;\n  return b;\n}\n\n// Special sum operation when a > b\nvec2 quickTwoSum(float a, float b) {\n#if defined(LUMA_FP64_CODE_ELIMINATION_WORKAROUND)\n  float sum = (a + b) * fp64.ONE;\n  float err = b - (sum - a) * fp64.ONE;\n#else\n  float sum = a + b;\n  float err = b - (sum - a);\n#endif\n  return vec2(sum, err);\n}\n\n// General sum operation\nvec2 twoSum(float a, float b) {\n  float s = (a + b);\n#if defined(LUMA_FP64_CODE_ELIMINATION_WORKAROUND)\n  float v = (s * fp64.ONE - a) * fp64.ONE;\n  float err = (a - (s - v) * fp64.ONE) * fp64.ONE * fp64.ONE * fp64.ONE + (b - v);\n#else\n  float v = s - a;\n  float err = (a - (s - v)) + (b - v);\n#endif\n  return vec2(s, err);\n}\n\nvec2 twoSub(float a, float b) {\n  float s = (a - b);\n#if defined(LUMA_FP64_CODE_ELIMINATION_WORKAROUND)\n  float v = (s * fp64.ONE - a) * fp64.ONE;\n  float err = (a - (s - v) * fp64.ONE) * fp64.ONE * fp64.ONE * fp64.ONE - (b + v);\n#else\n  float v = s - a;\n  float err = (a - (s - v)) - (b + v);\n#endif\n  return vec2(s, err);\n}\n\nvec2 twoSqr(float a) {\n  float prod = a * a;\n  vec2 a_fp64 = split(a);\n#if defined(LUMA_FP64_CODE_ELIMINATION_WORKAROUND)\n  float err = ((a_fp64.x * a_fp64.x - prod) * fp64.ONE + 2.0 * a_fp64.x *\n    a_fp64.y * fp64.ONE * fp64.ONE) + a_fp64.y * a_fp64.y * fp64.ONE * fp64.ONE * fp64.ONE;\n#else\n  float err = ((a_fp64.x * a_fp64.x - prod) + 2.0 * a_fp64.x * a_fp64.y) + a_fp64.y * a_fp64.y;\n#endif\n  return vec2(prod, err);\n}\n\nvec2 twoProd(float a, float b) {\n  float prod = a * b;\n  vec2 a_fp64 = split(a);\n  vec2 b_fp64 = split(b);\n  float err = ((a_fp64.x * b_fp64.x - prod) + a_fp64.x * b_fp64.y +\n    a_fp64.y * b_fp64.x) + a_fp64.y * b_fp64.y;\n  return vec2(prod, err);\n}\n\nvec2 sum_fp64(vec2 a, vec2 b) {\n  vec2 s, t;\n  s = twoSum(a.x, b.x);\n  t = twoSum(a.y, b.y);\n  s.y += t.x;\n  s = quickTwoSum(s.x, s.y);\n  s.y += t.y;\n  s = quickTwoSum(s.x, s.y);\n  return s;\n}\n\nvec2 sub_fp64(vec2 a, vec2 b) {\n  vec2 s, t;\n  s = twoSub(a.x, b.x);\n  t = twoSub(a.y, b.y);\n  s.y += t.x;\n  s = quickTwoSum(s.x, s.y);\n  s.y += t.y;\n  s = quickTwoSum(s.x, s.y);\n  return s;\n}\n\nvec2 mul_fp64(vec2 a, vec2 b) {\n  vec2 prod = twoProd(a.x, b.x);\n  // y component is for the error\n  prod.y += a.x * b.y;\n#if defined(LUMA_FP64_HIGH_BITS_OVERFLOW_WORKAROUND)\n  prod = split2(prod);\n#endif\n  prod = quickTwoSum(prod.x, prod.y);\n  prod.y += a.y * b.x;\n#if defined(LUMA_FP64_HIGH_BITS_OVERFLOW_WORKAROUND)\n  prod = split2(prod);\n#endif\n  prod = quickTwoSum(prod.x, prod.y);\n  return prod;\n}\n\nvec2 div_fp64(vec2 a, vec2 b) {\n  float xn = 1.0 / b.x;\n#if defined(LUMA_FP64_HIGH_BITS_OVERFLOW_WORKAROUND)\n  vec2 yn = mul_fp64(a, vec2(xn, 0));\n#else\n  vec2 yn = a * xn;\n#endif\n  float diff = (sub_fp64(a, mul_fp64(b, yn))).x;\n  vec2 prod = twoProd(xn, diff);\n  return sum_fp64(yn, prod);\n}\n\nvec2 sqrt_fp64(vec2 a) {\n  if (a.x == 0.0 && a.y == 0.0) return vec2(0.0, 0.0);\n  if (a.x < 0.0) return vec2(0.0 / 0.0, 0.0 / 0.0);\n\n  float x = 1.0 / sqrt(a.x);\n  float yn = a.x * x;\n#if defined(LUMA_FP64_CODE_ELIMINATION_WORKAROUND)\n  vec2 yn_sqr = twoSqr(yn) * fp64.ONE;\n#else\n  vec2 yn_sqr = twoSqr(yn);\n#endif\n  float diff = sub_fp64(a, yn_sqr).x;\n  vec2 prod = twoProd(x * 0.5, diff);\n#if defined(LUMA_FP64_HIGH_BITS_OVERFLOW_WORKAROUND)\n  return sum_fp64(split(yn), prod);\n#else\n  return sum_fp64(vec2(yn, 0.0), prod);\n#endif\n}\n";
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