diff options
Diffstat (limited to 'Alc/effects/reverb.c')
| -rw-r--r-- | Alc/effects/reverb.c | 121 |
1 files changed, 38 insertions, 83 deletions
diff --git a/Alc/effects/reverb.c b/Alc/effects/reverb.c index 46129934..bd5553ad 100644 --- a/Alc/effects/reverb.c +++ b/Alc/effects/reverb.c @@ -1060,97 +1060,52 @@ static ALvoid UpdateLateLines(const ALfloat density, const ALfloat diffusion, co } } -/* Creates a transform matrix given a reverb vector. This works by first - * creating an inverse rotation around Y then X, applying a Z-focus transform, - * then non-inverse rotations back around X then Y, to place the focal point in - * the direction of the vector, using the vector length as a focus strength. - * - * This convoluted construction ultimately results in a B-Format transformation - * matrix that retains its original orientation, but spatially focuses the - * signal in the desired direction. There is probably a more efficient way to - * do this, but let's see how good the optimizer is. +/* Creates a transform matrix given a reverb vector. The vector pans the reverb + * reflections toward the given direction, using its magnitude (up to 1) as a + * focal strength. This function results in a B-Format transformation matrix + * that spatially focuses the signal in the desired direction. */ static aluMatrixf GetTransformFromVector(const ALfloat *vec) { const ALfloat sqrt_3 = 1.732050808f; - aluMatrixf zfocus, xrot, yrot; - aluMatrixf tmp1, tmp2; - ALfloat length; - ALfloat sa, a; - - length = sqrtf(vec[0]*vec[0] + vec[1]*vec[1] + vec[2]*vec[2]); - - /* Define a Z-focus (X in Ambisonics) transform, given the panning vector - * length. + aluMatrixf focus; + ALfloat norm[3]; + ALfloat mag; + + /* Normalize the panning vector according to the N3D scale, which has an + * extra sqrt(3) term on the directional components. Converting from OpenAL + * to B-Format also requires negating X (ACN 1) and Z (ACN 3). Note however + * that the reverb panning vectors use right-handed coordinates, unlike the + * rest of OpenAL which use left-handed. This is fixed by negating Z, which + * cancels out with the B-Format Z negation. */ - sa = sinf(minf(length, 1.0f) * (F_PI/2.0f)); - aluMatrixfSet(&zfocus, - 1.0f/(1.0f+sa), 0.0f, 0.0f, sa/(1.0f+sa)/sqrt_3, - 0.0f, sqrtf((1.0f-sa)/(1.0f+sa)), 0.0f, 0.0f, - 0.0f, 0.0f, sqrtf((1.0f-sa)/(1.0f+sa)), 0.0f, - sa/(1.0f+sa)*sqrt_3, 0.0f, 0.0f, 1.0f/(1.0f+sa) - ); - - /* Define rotation around X (Y in Ambisonics) */ - a = atan2f(vec[1], sqrtf(vec[0]*vec[0] + vec[2]*vec[2])); - aluMatrixfSet(&xrot, - 1.0f, 0.0f, 0.0f, 0.0f, - 0.0f, 1.0f, 0.0f, 0.0f, - 0.0f, 0.0f, cosf(a), sinf(a), - 0.0f, 0.0f, -sinf(a), cosf(a) - ); + mag = sqrtf(vec[0]*vec[0] + vec[1]*vec[1] + vec[2]*vec[2]); + if(mag > 1.0f) + { + norm[0] = vec[0] / mag * -sqrt_3; + norm[1] = vec[1] / mag * sqrt_3; + norm[2] = vec[2] / mag * sqrt_3; + mag = 1.0f; + } + else + { + /* If the magnitude is less than or equal to 1, just apply the sqrt(3) + * term. There's no need to renormalize the magnitude since it would + * just be reapplied in the matrix. + */ + norm[0] = vec[0] * -sqrt_3; + norm[1] = vec[1] * sqrt_3; + norm[2] = vec[2] * sqrt_3; + } - /* Define rotation around Y (Z in Ambisonics). NOTE: EFX's reverb vectors - * use a right-handled coordinate system, compared to the rest of OpenAL - * which uses left-handed. This is fixed by negating Z, however it would - * need to also be negated to get a proper Ambisonics angle, thus - * cancelling it out. - */ - a = atan2f(-vec[0], vec[2]); - aluMatrixfSet(&yrot, - 1.0f, 0.0f, 0.0f, 0.0f, - 0.0f, cosf(a), 0.0f, sinf(a), - 0.0f, 0.0f, 1.0f, 0.0f, - 0.0f, -sinf(a), 0.0f, cosf(a) + aluMatrixfSet(&focus, + 1.0f, 0.0f, 0.0f, 0.0f, + norm[0], 1.0f-mag, 0.0f, 0.0f, + norm[1], 0.0f, 1.0f-mag, 0.0f, + norm[2], 0.0f, 0.0f, 1.0f-mag ); - /* First, define a matrix that applies the inverse of the Y- then X- - * rotation matrices, so that the desired direction lands on Z. - */ -#define MATRIX_INVMULT(_res, _m1, _m2) do { \ - int row, col; \ - for(col = 0;col < 4;col++) \ - { \ - for(row = 0;row < 4;row++) \ - _res.m[row][col] = _m1.m[0][row]*_m2.m[col][0] + \ - _m1.m[1][row]*_m2.m[col][1] + \ - _m1.m[2][row]*_m2.m[col][2] + \ - _m1.m[3][row]*_m2.m[col][3]; \ - } \ -} while(0) - MATRIX_INVMULT(tmp1, xrot, yrot); -#undef MATRIX_INVMULT - -#define MATRIX_MULT(_res, _m1, _m2) do { \ - int row, col; \ - for(col = 0;col < 4;col++) \ - { \ - for(row = 0;row < 4;row++) \ - _res.m[row][col] = _m1.m[row][0]*_m2.m[0][col] + \ - _m1.m[row][1]*_m2.m[1][col] + \ - _m1.m[row][2]*_m2.m[2][col] + \ - _m1.m[row][3]*_m2.m[3][col]; \ - } \ -} while(0) - /* Now apply matrices to focus on Z, then rotate back around X then Y, to - * result in a focus in the direction of the vector. - */ - MATRIX_MULT(tmp2, zfocus, tmp1); - MATRIX_MULT(tmp1, xrot, tmp2); - MATRIX_MULT(tmp2, yrot, tmp1); -#undef MATRIX_MULT - - return tmp2; + return focus; } /* Update the early and late 3D panning gains. */ |