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uniform sampler1D strand_data;
uniform int strand_map_start;
uniform int strand_vertex_start;
uniform int fiber_start;
uniform float ribbon_width;
uniform mat4 ModelViewMatrix;
uniform mat4 ProjectionMatrix;
uniform mat4 ModelViewProjectionMatrix;
uniform mat3 NormalMatrix;
uniform vec2 viewport_size;
in int fiber_index;
in float curve_param;
/* ---- Per instance Attribs ---- */
in mat4 InstanceModelMatrix;
out vec3 fPosition;
out vec3 fTangent;
out vec3 fColor;
#ifdef WITH_DEBUG
out ivec4 dbgParentIndex;
out vec4 dbgParentWeight;
out vec3 dbgRootPosition;
#endif
#define M_PI 3.1415926535897932384626433832795
#define INDEX_INVALID -1
mat3 mat3_from_vectors(vec3 nor, vec3 tang)
{
tang = normalize(tang);
vec3 xnor = normalize(cross(nor, tang));
return mat3(tang, xnor, cross(tang, xnor));
}
void get_strand_data(int index, out int start, out int count)
{
int offset = strand_map_start + index;
vec4 a = texelFetch(strand_data, offset, 0);
start = floatBitsToInt(a.r);
count = floatBitsToInt(a.g);
}
void get_strand_vertex(int index, out vec3 co, out vec3 nor, out vec3 tang)
{
int offset = strand_vertex_start + index * 5;
vec4 a = texelFetch(strand_data, offset, 0);
vec4 b = texelFetch(strand_data, offset + 1, 0);
vec4 c = texelFetch(strand_data, offset + 2, 0);
vec4 d = texelFetch(strand_data, offset + 3, 0);
vec4 e = texelFetch(strand_data, offset + 4, 0);
co = vec3(a.rg, b.r);
nor = vec3(b.g, c.rg);
tang = vec3(d.rg, e.r);
}
void get_strand_root(int index, out vec3 co)
{
int offset = strand_vertex_start + index * 5;
vec4 a = texelFetch(strand_data, offset, 0);
vec4 b = texelFetch(strand_data, offset + 1, 0);
co = vec3(a.rg, b.r);
}
void get_fiber_data(out ivec4 parent_index, out vec4 parent_weight, out vec3 pos)
{
int offset = fiber_start + fiber_index * 6;
vec4 a = texelFetch(strand_data, offset, 0);
vec4 b = texelFetch(strand_data, offset + 1, 0);
vec4 c = texelFetch(strand_data, offset + 2, 0);
vec4 d = texelFetch(strand_data, offset + 3, 0);
vec4 e = texelFetch(strand_data, offset + 4, 0);
vec4 f = texelFetch(strand_data, offset + 5, 0);
parent_index = ivec4(floatBitsToInt(a.rg), floatBitsToInt(b.rg));
parent_weight = vec4(c.rg, d.rg);
pos = vec3(e.rg, f.r);
#ifdef WITH_DEBUG
dbgParentIndex = parent_index;
dbgParentWeight = parent_weight;
dbgRootPosition = pos;
#endif
}
void interpolate_parent_curve(int index, out vec3 co, out vec3 nor, out vec3 tang)
{
int start, count;
get_strand_data(index, start, count);
vec3 rootco;
get_strand_root(start, rootco);
#if 0 // Don't have to worry about out-of-bounds segment here, as long as lerpfac becomes 0.0 when curve_param==1.0
float maxlen = float(count - 1);
float arclength = curve_param * maxlen;
int segment = min(int(arclength), count - 2);
float lerpfac = arclength - min(floor(arclength), maxlen - 1.0);
#else
float maxlen = float(count - 1);
float arclength = curve_param * maxlen;
int segment = int(arclength);
float lerpfac = arclength - floor(arclength);
#endif
vec3 co0, nor0, tang0;
vec3 co1, nor1, tang1;
get_strand_vertex(start + segment, co0, nor0, tang0);
get_strand_vertex(start + segment + 1, co1, nor1, tang1);
co = mix(co0, co1, lerpfac) - rootco;
nor = mix(nor0, nor1, lerpfac);
tang = mix(tang0, tang1, lerpfac);
}
void interpolate_vertex(out vec3 co, out vec3 tang,
out vec3 target_co, out mat3 target_matrix)
{
ivec4 parent_index;
vec4 parent_weight;
vec3 rootpos;
get_fiber_data(parent_index, parent_weight, rootpos);
co = vec3(0.0);
tang = vec3(0.0);
target_co = vec3(0.0);
target_matrix = mat3(1.0);
vec3 pco, pnor, ptang;
if (parent_index.x != INDEX_INVALID) {
interpolate_parent_curve(parent_index.x, pco, pnor, ptang);
co += parent_weight.x * pco;
tang += parent_weight.x * normalize(ptang);
target_co = co;
target_matrix = mat3_from_vectors(pnor, ptang);
}
if (parent_index.y != INDEX_INVALID) {
interpolate_parent_curve(parent_index.y, pco, pnor, ptang);
co += parent_weight.y * pco;
tang += parent_weight.y * normalize(ptang);
}
if (parent_index.z != INDEX_INVALID) {
interpolate_parent_curve(parent_index.z, pco, pnor, ptang);
co += parent_weight.z * pco;
tang += parent_weight.z * normalize(ptang);
}
if (parent_index.w != INDEX_INVALID) {
interpolate_parent_curve(parent_index.w, pco, pnor, ptang);
co += parent_weight.w * pco;
tang += parent_weight.w * normalize(ptang);
}
co += rootpos;
tang = normalize(tang);
}
void displace_vertex(inout vec3 loc, inout vec3 tang, in float t, in float tscale, in vec3 target_loc, in mat3 target_frame)
{
// TODO
}
void main()
{
vec3 loc, tang, target_loc;
mat3 target_frame;
interpolate_vertex(loc, tang, target_loc, target_frame);
// TODO define proper curve scale, independent of subdivision!
displace_vertex(loc, tang, curve_param, 1.0, target_loc, target_frame);
mat4 InstanceViewMatrix = ModelViewMatrix * InstanceModelMatrix;
vec4 co = InstanceViewMatrix * vec4(loc, 1.0);
fPosition = vec3(co);
fTangent = vec3(ProjectionMatrix * InstanceViewMatrix * vec4(tang, 0.0));
fColor = vec3(1,1,0);
gl_Position = ProjectionMatrix * co;
#ifdef FIBER_RIBBON
float ribbon_side = (float(gl_VertexID % 2) - 0.5) * ribbon_width;
vec2 view_offset = normalize(vec2(fTangent.y, -fTangent.x)) / viewport_size * ribbon_side;
gl_Position = vec4(gl_Position.xyz + vec3(view_offset, 0.0) * gl_Position.w, gl_Position.w);
#endif
}
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