diff options
Diffstat (limited to 'source/blender/draw/engines/eevee/shaders/ltc_lib.glsl')
| -rw-r--r-- | source/blender/draw/engines/eevee/shaders/ltc_lib.glsl | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/source/blender/draw/engines/eevee/shaders/ltc_lib.glsl b/source/blender/draw/engines/eevee/shaders/ltc_lib.glsl new file mode 100644 index 00000000000..131b0c2de78 --- /dev/null +++ b/source/blender/draw/engines/eevee/shaders/ltc_lib.glsl @@ -0,0 +1,243 @@ +/* Mainly From https://eheitzresearch.wordpress.com/415-2/ */ + +#define USE_LTC +#define LTC_LUT_SIZE 64 + +uniform sampler2D ltcMat; +uniform sampler2D ltcMag; + +/* from Real-Time Area Lighting: a Journey from Research to Production + * Stephen Hill and Eric Heitz */ +float edge_integral(vec3 p1, vec3 p2) +{ +#if 0 + /* more accurate replacement of acos */ + float x = dot(p1, p2); + float y = abs(x); + + float a = 5.42031 + (3.12829 + 0.0902326 * y) * y; + float b = 3.45068 + (4.18814 + y) * y; + float theta_sintheta = a / b; + + if (x < 0.0) { + theta_sintheta = (M_PI / sqrt(1.0 - x * x)) - theta_sintheta; + } + vec3 u = cross(p1, p2); + return theta_sintheta * dot(u, N); +#endif + float cos_theta = dot(p1, p2); + cos_theta = clamp(cos_theta, -0.9999, 0.9999); + + float theta = acos(cos_theta); + vec3 u = normalize(cross(p1, p2)); + return theta * cross(p1, p2).z / sin(theta); +} + +int clip_quad_to_horizon(inout vec3 L[5]) +{ + /* detect clipping config */ + int config = 0; + if (L[0].z > 0.0) config += 1; + if (L[1].z > 0.0) config += 2; + if (L[2].z > 0.0) config += 4; + if (L[3].z > 0.0) config += 8; + + /* clip */ + int n = 0; + + if (config == 0) + { + /* clip all */ + } + else if (config == 1) /* V1 clip V2 V3 V4 */ + { + n = 3; + L[1] = -L[1].z * L[0] + L[0].z * L[1]; + L[2] = -L[3].z * L[0] + L[0].z * L[3]; + } + else if (config == 2) /* V2 clip V1 V3 V4 */ + { + n = 3; + L[0] = -L[0].z * L[1] + L[1].z * L[0]; + L[2] = -L[2].z * L[1] + L[1].z * L[2]; + } + else if (config == 3) /* V1 V2 clip V3 V4 */ + { + n = 4; + L[2] = -L[2].z * L[1] + L[1].z * L[2]; + L[3] = -L[3].z * L[0] + L[0].z * L[3]; + } + else if (config == 4) /* V3 clip V1 V2 V4 */ + { + n = 3; + L[0] = -L[3].z * L[2] + L[2].z * L[3]; + L[1] = -L[1].z * L[2] + L[2].z * L[1]; + } + else if (config == 5) /* V1 V3 clip V2 V4) impossible */ + { + n = 0; + } + else if (config == 6) /* V2 V3 clip V1 V4 */ + { + n = 4; + L[0] = -L[0].z * L[1] + L[1].z * L[0]; + L[3] = -L[3].z * L[2] + L[2].z * L[3]; + } + else if (config == 7) /* V1 V2 V3 clip V4 */ + { + n = 5; + L[4] = -L[3].z * L[0] + L[0].z * L[3]; + L[3] = -L[3].z * L[2] + L[2].z * L[3]; + } + else if (config == 8) /* V4 clip V1 V2 V3 */ + { + n = 3; + L[0] = -L[0].z * L[3] + L[3].z * L[0]; + L[1] = -L[2].z * L[3] + L[3].z * L[2]; + L[2] = L[3]; + } + else if (config == 9) /* V1 V4 clip V2 V3 */ + { + n = 4; + L[1] = -L[1].z * L[0] + L[0].z * L[1]; + L[2] = -L[2].z * L[3] + L[3].z * L[2]; + } + else if (config == 10) /* V2 V4 clip V1 V3) impossible */ + { + n = 0; + } + else if (config == 11) /* V1 V2 V4 clip V3 */ + { + n = 5; + L[4] = L[3]; + L[3] = -L[2].z * L[3] + L[3].z * L[2]; + L[2] = -L[2].z * L[1] + L[1].z * L[2]; + } + else if (config == 12) /* V3 V4 clip V1 V2 */ + { + n = 4; + L[1] = -L[1].z * L[2] + L[2].z * L[1]; + L[0] = -L[0].z * L[3] + L[3].z * L[0]; + } + else if (config == 13) /* V1 V3 V4 clip V2 */ + { + n = 5; + L[4] = L[3]; + L[3] = L[2]; + L[2] = -L[1].z * L[2] + L[2].z * L[1]; + L[1] = -L[1].z * L[0] + L[0].z * L[1]; + } + else if (config == 14) /* V2 V3 V4 clip V1 */ + { + n = 5; + L[4] = -L[0].z * L[3] + L[3].z * L[0]; + L[0] = -L[0].z * L[1] + L[1].z * L[0]; + } + else if (config == 15) /* V1 V2 V3 V4 */ + { + n = 4; + } + + if (n == 3) + L[3] = L[0]; + if (n == 4) + L[4] = L[0]; + + return n; +} + +vec2 ltc_coords(float cosTheta, float roughness) +{ + float theta = acos(cosTheta); + vec2 coords = vec2(roughness, theta/(0.5*3.14159)); + + /* scale and bias coordinates, for correct filtered lookup */ + return coords * (LTC_LUT_SIZE - 1.0) / LTC_LUT_SIZE + 0.5 / LTC_LUT_SIZE; +} + +mat3 ltc_matrix(vec2 coord) +{ + /* load inverse matrix */ + vec4 t = texture(ltcMat, coord); + mat3 Minv = mat3( + vec3( 1, 0, t.y), + vec3( 0, t.z, 0), + vec3(t.w, 0, t.x) + ); + + return Minv; +} + +float ltc_evaluate(vec3 N, vec3 V, mat3 Minv, vec3 corners[4]) +{ + /* construct orthonormal basis around N */ + vec3 T1, T2; + T1 = normalize(V - N*dot(V, N)); + T2 = cross(N, T1); + + /* rotate area light in (T1, T2, R) basis */ + Minv = Minv * transpose(mat3(T1, T2, N)); + + /* polygon (allocate 5 vertices for clipping) */ + vec3 L[5]; + L[0] = Minv * corners[0]; + L[1] = Minv * corners[1]; + L[2] = Minv * corners[2]; + L[3] = Minv * corners[3]; + + int n = clip_quad_to_horizon(L); + + if (n == 0) + return 0.0; + + /* project onto sphere */ + L[0] = normalize(L[0]); + L[1] = normalize(L[1]); + L[2] = normalize(L[2]); + L[3] = normalize(L[3]); + L[4] = normalize(L[4]); + + /* integrate */ + float sum = 0.0; + + sum += edge_integral(L[0], L[1]); + sum += edge_integral(L[1], L[2]); + sum += edge_integral(L[2], L[3]); + if (n >= 4) + sum += edge_integral(L[3], L[4]); + if (n == 5) + sum += edge_integral(L[4], L[0]); + + return abs(sum); +} + +/* Aproximate circle with an octogone */ +#define LTC_CIRCLE_RES 8 +float ltc_evaluate_circle(vec3 N, vec3 V, mat3 Minv, vec3 p[LTC_CIRCLE_RES]) +{ + /* construct orthonormal basis around N */ + vec3 T1, T2; + T1 = normalize(V - N*dot(V, N)); + T2 = cross(N, T1); + + /* rotate area light in (T1, T2, R) basis */ + Minv = Minv * transpose(mat3(T1, T2, N)); + + for (int i = 0; i < LTC_CIRCLE_RES; ++i) { + p[i] = Minv * p[i]; + /* clip to horizon */ + p[i].z = max(0.0, p[i].z); + /* project onto sphere */ + p[i] = normalize(p[i]); + } + + /* integrate */ + float sum = 0.0; + for (int i = 0; i < LTC_CIRCLE_RES - 1; ++i) { + sum += edge_integral(p[i], p[i + 1]); + } + sum += edge_integral(p[LTC_CIRCLE_RES - 1], p[0]); + + return max(0.0, sum); +} + |