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/* Starshatter: The Open Source Project
Copyright (c) 2021-2022, Starshatter: The Open Source Project Contributors
Copyright (c) 2011-2012, Starshatter OpenSource Distribution Contributors
Copyright (c) 1997-2006, Destroyer Studios LLC.
AUTHOR: John DiCamillo
OVERVIEW
========
Dynamic Stencil Shadow Volumes
*/
#include "Shadow.h"
#include "Light.h"
#include "Solid.h"
#include "Scene.h"
#include "Video.h"
static bool visible_shadow_volumes = false;
// +--------------------------------------------------------------------+
Shadow::Shadow(Solid* s)
: verts(0), nverts(0), max_verts(0), edges(0), num_edges(0), enabled(true)
{
solid = s;
if (solid && solid->GetModel()) {
Model* model = solid->GetModel();
int npolys = model->NumPolys();
max_verts = model->NumVerts() * 4;
verts = new Vec3[max_verts];
edges = new WORD[npolys * 6];
}
}
// +--------------------------------------------------------------------+
Shadow::~Shadow()
{
if (verts) delete [] verts;
if (edges) delete [] edges;
}
// +--------------------------------------------------------------------+
void
Shadow::Reset()
{
num_edges = 0;
nverts = 0;
}
// +--------------------------------------------------------------------+
void
Shadow::Render(Video* video)
{
if (enabled)
video->DrawShadow(solid, nverts, verts, visible_shadow_volumes);
}
// +--------------------------------------------------------------------+
void
Shadow::Update(Light* light)
{
Reset();
if (!light || !solid || !solid->GetModel() || !edges) return;
Vec3 lpos = light->Location();
bool directional = light->Type() == Light::LIGHT_DIRECTIONAL;
Model* model = solid->GetModel();
ListIter<Surface> iter = model->GetSurfaces();
while (++iter) {
Surface* s = iter.value();
// transform light location into surface object space
Matrix xform(solid->Orientation()); // XXX should be: (s->GetOrientation());
Vec3 tmp = light->Location();
if (!directional)
tmp -= (solid->Location() + s->GetOffset());
lpos.x = tmp * Vec3(xform(0,0), xform(0,1), xform(0,2));
lpos.y = tmp * Vec3(xform(1,0), xform(1,1), xform(1,2));
lpos.z = tmp * Vec3(xform(2,0), xform(2,1), xform(2,2));
// compute the silohuette for the mesh with respect to the light:
for (int i = 0; i < s->NumPolys(); i++) {
Poly* p = s->GetPolys() + i;
// skip polys with non-shadowing materials:
if (p->material && !p->material->shadow)
continue;
// if this poly faces the light:
if (p->plane.normal * lpos > 0) {
for (int n = 0; n < p->nverts; n++) {
if (n < p->nverts-1)
AddEdge(p->vlocs[n], p->vlocs[n+1]);
else
AddEdge(p->vlocs[n], p->vlocs[0]);
}
}
}
// extrude the silohuette away from the light source
// to create the shadow volume:
Vec3 extent = lpos * -1;
extent.Normalize();
extent *= 50.0e3f; //solid->Radius() * 2.1f;
for (int i = 0; i < (int) num_edges; i++) {
if (nverts+6 <= max_verts) {
Vec3 v1 = s->GetVLoc()[edges[2*i+0]];
Vec3 v2 = s->GetVLoc()[edges[2*i+1]];
Vec3 v3 = v1 + extent;
Vec3 v4 = v2 + extent;
verts[nverts++] = v1;
verts[nverts++] = v2;
verts[nverts++] = v3;
verts[nverts++] = v2;
verts[nverts++] = v4;
verts[nverts++] = v3;
}
}
}
}
void
Shadow::AddEdge(WORD v1, WORD v2)
{
// Remove interior edges (which appear in the list twice)
for (DWORD i = 0; i < num_edges; i++) {
if ((edges[2*i+0] == v1 && edges[2*i+1] == v2) ||
(edges[2*i+0] == v2 && edges[2*i+1] == v1))
{
if (num_edges > 1) {
edges[2*i+0] = edges[2*(num_edges-1)+0];
edges[2*i+1] = edges[2*(num_edges-1)+1];
}
num_edges--;
return;
}
}
edges[2*num_edges+0] = v1;
edges[2*num_edges+1] = v2;
num_edges++;
}
bool
Shadow::GetVisibleShadowVolumes()
{
return visible_shadow_volumes;
}
void
Shadow::SetVisibleShadowVolumes(bool vis)
{
visible_shadow_volumes = vis;
}
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