svm_musgrave.h

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/*
 * Copyright 2011, Blender Foundation.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

CCL_NAMESPACE_BEGIN

/* Musgrave fBm
 *
 * H: fractal increment parameter
 * lacunarity: gap between successive frequencies
 * octaves: number of frequencies in the fBm
 *
 * from "Texturing and Modelling: A procedural approach"
 */

__device_noinline float noise_musgrave_fBm(float3 p, NodeNoiseBasis basis, float H, float lacunarity, float octaves)
{
    float rmd;
    float value = 0.0f;
    float pwr = 1.0f;
    float pwHL = pow(lacunarity, -H);
    int i;

    for(i = 0; i < (int)octaves; i++) {
        value += snoise(p) * pwr;
        pwr *= pwHL;
        p *= lacunarity;
    }

    rmd = octaves - floor(octaves);
    if(rmd != 0.0f)
        value += rmd * snoise(p) * pwr;

    return value;
}

/* Musgrave Multifractal
 *
 * H: highest fractal dimension
 * lacunarity: gap between successive frequencies
 * octaves: number of frequencies in the fBm
 */

__device_noinline float noise_musgrave_multi_fractal(float3 p, NodeNoiseBasis basis, float H, float lacunarity, float octaves)
{
    float rmd;
    float value = 1.0f;
    float pwr = 1.0f;
    float pwHL = pow(lacunarity, -H);
    int i;

    for(i = 0; i < (int)octaves; i++) {
        value *= (pwr * snoise(p) + 1.0f);
        pwr *= pwHL;
        p *= lacunarity;
    }

    rmd = octaves - floor(octaves);
    if(rmd != 0.0f)
        value *= (rmd * pwr * snoise(p) + 1.0f); /* correct? */

    return value;
}

/* Musgrave Heterogeneous Terrain
 *
 * H: fractal dimension of the roughest area
 * lacunarity: gap between successive frequencies
 * octaves: number of frequencies in the fBm
 * offset: raises the terrain from `sea level'
 */

__device_noinline float noise_musgrave_hetero_terrain(float3 p, NodeNoiseBasis basis, float H, float lacunarity, float octaves, float offset)
{
    float value, increment, rmd;
    float pwHL = pow(lacunarity, -H);
    float pwr = pwHL;
    int i;

    /* first unscaled octave of function; later octaves are scaled */
    value = offset + snoise(p);
    p *= lacunarity;

    for(i = 1; i < (int)octaves; i++) {
        increment = (snoise(p) + offset) * pwr * value;
        value += increment;
        pwr *= pwHL;
        p *= lacunarity;
    }

    rmd = octaves - floor(octaves);
    if(rmd != 0.0f) {
        increment = (snoise(p) + offset) * pwr * value;
        value += rmd * increment;
    }

    return value;
}

/* Hybrid Additive/Multiplicative Multifractal Terrain
 *
 * H: fractal dimension of the roughest area
 * lacunarity: gap between successive frequencies
 * octaves: number of frequencies in the fBm
 * offset: raises the terrain from `sea level'
 */

__device_noinline float noise_musgrave_hybrid_multi_fractal(float3 p, NodeNoiseBasis basis, float H, float lacunarity, float octaves, float offset, float gain)
{
    float result, signal, weight, rmd;
    float pwHL = pow(lacunarity, -H);
    float pwr = pwHL;
    int i;

    result = snoise(p) + offset;
    weight = gain * result;
    p *= lacunarity;

    for(i = 1; (weight > 0.001f) && (i < (int)octaves); i++) {
        if(weight > 1.0f)
            weight = 1.0f;

        signal = (snoise(p) + offset) * pwr;
        pwr *= pwHL;
        result += weight * signal;
        weight *= gain * signal;
        p *= lacunarity;
    }

    rmd = octaves - floor(octaves);
    if(rmd != 0.0f)
        result += rmd * ((snoise(p) + offset) * pwr);

    return result;
}

/* Ridged Multifractal Terrain
 *
 * H: fractal dimension of the roughest area
 * lacunarity: gap between successive frequencies
 * octaves: number of frequencies in the fBm
 * offset: raises the terrain from `sea level'
 */

__device_noinline float noise_musgrave_ridged_multi_fractal(float3 p, NodeNoiseBasis basis, float H, float lacunarity, float octaves, float offset, float gain)
{
    float result, signal, weight;
    float pwHL = pow(lacunarity, -H);
    float pwr = pwHL;
    int i;

    signal = offset - fabsf(snoise(p));
    signal *= signal;
    result = signal;
    weight = 1.0f;

    for(i = 1; i < (int)octaves; i++) {
        p *= lacunarity;
        weight = clamp(signal * gain, 0.0f, 1.0f);
        signal = offset - fabsf(snoise(p));
        signal *= signal;
        signal *= weight;
        result += signal * pwr;
        pwr *= pwHL;
    }

    return result;
}

/* Shader */

__device float svm_musgrave(NodeMusgraveType type, float dimension, float lacunarity, float octaves, float offset, float intensity, float gain, float scale, float3 p)
{
    NodeNoiseBasis basis = NODE_NOISE_PERLIN;
    p *= scale;

    if(type == NODE_MUSGRAVE_MULTIFRACTAL)
        return intensity*noise_musgrave_multi_fractal(p, basis, dimension, lacunarity, octaves);
    else if(type == NODE_MUSGRAVE_FBM)
        return intensity*noise_musgrave_fBm(p, basis, dimension, lacunarity, octaves);
    else if(type == NODE_MUSGRAVE_HYBRID_MULTIFRACTAL)
        return intensity*noise_musgrave_hybrid_multi_fractal(p, basis, dimension, lacunarity, octaves, offset, gain);
    else if(type == NODE_MUSGRAVE_RIDGED_MULTIFRACTAL)
        return intensity*noise_musgrave_ridged_multi_fractal(p, basis, dimension, lacunarity, octaves, offset, gain);
    else if(type == NODE_MUSGRAVE_HETERO_TERRAIN)
        return intensity*noise_musgrave_hetero_terrain(p, basis, dimension, lacunarity, octaves, offset);
    
    return 0.0f;
}

__device void svm_node_tex_musgrave(KernelGlobals *kg, ShaderData *sd, float *stack, uint4 node, int *offset)
{
    uint4 node2 = read_node(kg, offset);
    uint4 node3 = read_node(kg, offset);

    uint type, co_offset, color_offset, fac_offset;
    uint dimension_offset, lacunarity_offset, detail_offset, offset_offset;
    uint gain_offset, scale_offset;

    decode_node_uchar4(node.y, &type, &co_offset, &color_offset, &fac_offset);
    decode_node_uchar4(node.z, &dimension_offset, &lacunarity_offset, &detail_offset, &offset_offset);
    decode_node_uchar4(node.w, &gain_offset, &scale_offset, NULL, NULL);

    float3 co = stack_load_float3(stack, co_offset);
    float dimension = stack_load_float_default(stack, dimension_offset, node2.x);
    float lacunarity = stack_load_float_default(stack, lacunarity_offset, node2.y);
    float detail = stack_load_float_default(stack, detail_offset, node2.z);
    float foffset = stack_load_float_default(stack, offset_offset, node2.w);
    float gain = stack_load_float_default(stack, gain_offset, node3.x);
    float scale = stack_load_float_default(stack, scale_offset, node3.y);

    dimension = fmaxf(dimension, 1e-5f);
    detail = clamp(detail, 0.0f, 16.0f);
    lacunarity = fmaxf(lacunarity, 1e-5f);

    float f = svm_musgrave((NodeMusgraveType)type,
        dimension, lacunarity, detail, foffset, 1.0f, gain, scale, co);

    if(stack_valid(fac_offset))
        stack_store_float(stack, fac_offset, f);
    if(stack_valid(color_offset))
        stack_store_float3(stack, color_offset, make_float3(f, f, f));
}

CCL_NAMESPACE_END