X-Git-Url: https://harrygodden.com/git/?a=blobdiff_plain;f=vg_m.h;h=68e2304a339c13013eae62c3dd3644a62ae6118e;hb=7a1b2ba3172f9f296df110997e5b8cca5f10ab68;hp=6d86177894e97f75273c7f67e9c6b4be0bd0e2e2;hpb=87adbb9de6b8c68b912179ae00cbd49181c2945a;p=vg.git diff --git a/vg_m.h b/vg_m.h index 6d86177..68e2304 100644 --- a/vg_m.h +++ b/vg_m.h @@ -132,6 +132,16 @@ static f32 vg_dequantf( u32 q, u32 bits, f32 min, f32 max ){ return min + (f32)q * ((max-min) / (f32)mask); } +/* https://iquilezles.org/articles/functions/ + * + * Use k to control the stretching of the function. Its maximum, which is 1, + * happens at exactly x = 1/k. + */ +static f32 vg_exp_impulse( f32 x, f32 k ){ + f32 h = k*x; + return h*expf(1.0f-h); +} + /* * ----------------------------------------------------------------------------- * Section 2.a 2D Vectors @@ -540,6 +550,34 @@ static void v3_tangent_basis( v3f n, v3f tx, v3f ty ){ v3_cross( n, tx, ty ); } +/* + * Compute yaw and pitch based of a normalized vector representing forward + * forward: -z + * result -> (YAW,PITCH,0.0) + */ +static void v3_angles( v3f v, v3f out_angles ){ + float yaw = atan2f( v[0], -v[2] ), + pitch = atan2f( + -v[1], + sqrtf( + v[0]*v[0] + v[2]*v[2] + ) + ); + + out_angles[0] = yaw; + out_angles[1] = pitch; + out_angles[2] = 0.0f; +} + +/* + * Compute the forward vector from (YAW,PITCH,ROLL) + * forward: -z + */ +static void v3_angles_vector( v3f angles, v3f out_v ){ + out_v[0] = sinf( angles[0] ) * cosf( angles[1] ); + out_v[1] = -sinf( angles[1] ); + out_v[2] = -cosf( angles[0] ) * cosf( angles[1] ); +} /* * ----------------------------------------------------------------------------- @@ -2239,59 +2277,55 @@ static float vg_sphere_volume( float radius ){ /* changes to STATE_VECTOR_LENGTH also require changes to this */ #define MT_STATE_VECTOR_M 397 -struct { +typedef struct vg_rand vg_rand; +struct vg_rand { u32 mt[MT_STATE_VECTOR_LENGTH]; i32 index; -} -static vg_rand; +}; -static void vg_rand_seed( unsigned long seed ) -{ +static void vg_rand_seed( vg_rand *rand, unsigned long seed ) { /* set initial seeds to mt[STATE_VECTOR_LENGTH] using the generator * from Line 25 of Table 1 in: Donald Knuth, "The Art of Computer * Programming," Vol. 2 (2nd Ed.) pp.102. */ - vg_rand.mt[0] = seed & 0xffffffff; - for( vg_rand.index=1; vg_rand.indexmt[0] = seed & 0xffffffff; + for( rand->index=1; rand->indexindex++){ + rand->mt[rand->index] = (6069 * rand->mt[rand->index-1]) & 0xffffffff; } } /* * Generates a pseudo-randomly generated long. */ -static u32 vg_randu32(void) -{ +static u32 vg_randu32( vg_rand *rand ) { u32 y; /* mag[x] = x * 0x9908b0df for x = 0,1 */ static u32 mag[2] = {0x0, 0x9908b0df}; - if( vg_rand.index >= MT_STATE_VECTOR_LENGTH || vg_rand.index < 0 ){ + if( rand->index >= MT_STATE_VECTOR_LENGTH || rand->index < 0 ){ /* generate STATE_VECTOR_LENGTH words at a time */ int kk; - if( vg_rand.index >= MT_STATE_VECTOR_LENGTH+1 || vg_rand.index < 0 ){ - vg_rand_seed( 4357 ); + if( rand->index >= MT_STATE_VECTOR_LENGTH+1 || rand->index < 0 ){ + vg_rand_seed( rand, 4357 ); } for( kk=0; kk> 1) ^ mag[y & 0x1]; + y = (rand->mt[kk] & MT_UPPER_MASK) | + (rand->mt[kk+1] & MT_LOWER_MASK); + rand->mt[kk] = rand->mt[kk+MT_STATE_VECTOR_M] ^ (y>>1) ^ mag[y & 0x1]; } for( ; kkmt[kk] & MT_UPPER_MASK) | + (rand->mt[kk+1] & MT_LOWER_MASK); + rand->mt[kk] = + rand->mt[ kk+(MT_STATE_VECTOR_M-MT_STATE_VECTOR_LENGTH)] ^ (y >> 1) ^ mag[y & 0x1]; } - y = (vg_rand.mt[MT_STATE_VECTOR_LENGTH-1] & MT_UPPER_MASK) | - (vg_rand.mt[0] & MT_LOWER_MASK); - vg_rand.mt[MT_STATE_VECTOR_LENGTH-1] = - vg_rand.mt[MT_STATE_VECTOR_M-1] ^ (y >> 1) ^ mag[y & 0x1]; - vg_rand.index = 0; + y = (rand->mt[MT_STATE_VECTOR_LENGTH-1] & MT_UPPER_MASK) | + (rand->mt[0] & MT_LOWER_MASK); + rand->mt[MT_STATE_VECTOR_LENGTH-1] = + rand->mt[MT_STATE_VECTOR_M-1] ^ (y >> 1) ^ mag[y & 0x1]; + rand->index = 0; } - y = vg_rand.mt[vg_rand.index++]; + y = rand->mt[rand->index++]; y ^= (y >> 11); y ^= (y << 7) & MT_TEMPERING_MASK_B; y ^= (y << 15) & MT_TEMPERING_MASK_C; @@ -2302,21 +2336,21 @@ static u32 vg_randu32(void) /* * Generates a pseudo-randomly generated f64 in the range [0..1]. */ -static inline f64 vg_randf64(void) -{ - return (f64)vg_randu32()/(f64)0xffffffff; +static inline f64 vg_randf64( vg_rand *rand ){ + return (f64)vg_randu32(rand)/(f64)0xffffffff; } -static inline f64 vg_randf64_range( f64 min, f64 max ) -{ - return vg_lerp( min, max, (f64)vg_randf64() ); +static inline f64 vg_randf64_range( vg_rand *rand, f64 min, f64 max ){ + return vg_lerp( min, max, (f64)vg_randf64(rand) ); } -static inline void vg_rand_dir( v3f dir ) -{ - dir[0] = vg_randf64(); - dir[1] = vg_randf64(); - dir[2] = vg_randf64(); +static inline void vg_rand_dir( vg_rand *rand, v3f dir ){ + dir[0] = vg_randf64(rand); + dir[1] = vg_randf64(rand); + dir[2] = vg_randf64(rand); + + /* warning: *could* be 0 length. + * very unlikely.. 1 in (2^32)^3. but its mathematically wrong. */ v3_muls( dir, 2.0f, dir ); v3_sub( dir, (v3f){1.0f,1.0f,1.0f}, dir ); @@ -2324,10 +2358,25 @@ static inline void vg_rand_dir( v3f dir ) v3_normalize( dir ); } -static inline void vg_rand_sphere( v3f co ) -{ - vg_rand_dir(co); - v3_muls( co, cbrtf( vg_randf64() ), co ); +static inline void vg_rand_sphere( vg_rand *rand, v3f co ){ + vg_rand_dir(rand,co); + v3_muls( co, cbrtf( vg_randf64(rand) ), co ); +} + +static void vg_rand_disc( vg_rand *rand, v2f co ){ + f32 a = vg_randf64(rand) * VG_TAUf; + co[0] = sinf(a); + co[1] = cosf(a); + v2_muls( co, sqrtf( vg_randf64(rand) ), co ); +} + +static void vg_rand_cone( vg_rand *rand, v3f out_dir, f32 angle ){ + f32 r = sqrtf(vg_randf64(rand)) * angle * 0.5f, + a = vg_randf64(rand) * VG_TAUf; + + out_dir[0] = sinf(a) * sinf(r); + out_dir[1] = cosf(a) * sinf(r); + out_dir[2] = cosf(r); } #endif /* VG_M_H */