From 04d50b8bbe324fdb7a8a1e724fbc59c4050862f0 Mon Sep 17 00:00:00 2001
From: rodri <rgl@antares-labs.eu>
Date: Sat, 13 Jul 2024 10:23:52 +0000
Subject: fix the geometry glitches when moving things around.

it's possible for interactive programs to keep updating
the geometry of the scene during rendering, which caused
primitives to look deformed or shattered in the final
image.

to avoid this we take a snapshot of the current state of
things (scene and camera), and render based on that copy.
---
 camera.c | 67 +++++++++++++++++++++++++++++++++++++---------------------------
 1 file changed, 39 insertions(+), 28 deletions(-)

(limited to 'camera.c')

diff --git a/camera.c b/camera.c
index 60f3c4a..ed220a3 100644
--- a/camera.c
+++ b/camera.c
@@ -106,6 +106,36 @@ verifycfg(Camera *c)
 	assert(c->clip.n > 0 && c->clip.n < c->clip.f);
 }
 
+/* TODO the current camera abstraction is quite dirty, not pleasant to work with. make it better. */
+//Camera *
+//Cam(Camcfg cfg)
+//{
+//	
+//}
+
+void
+reloadcamera(Camera *c)
+{
+	double a;
+	double l, r, b, t;
+
+	verifycfg(c);
+	switch(c->projtype){
+	case ORTHOGRAPHIC:
+		r = Dx(c->vp->fbctl->fb[0]->r)/2;
+		t = Dy(c->vp->fbctl->fb[0]->r)/2;
+		l = -r;
+		b = -t;
+		orthographic(c->proj, l, r, b, t, c->clip.n, c->clip.f);
+		break;
+	case PERSPECTIVE:
+		a = (double)Dx(c->vp->fbctl->fb[0]->r)/Dy(c->vp->fbctl->fb[0]->r);
+		perspective(c->proj, c->fov, a, c->clip.n, c->clip.f);
+		break;
+	default: sysfatal("unknown projection type");
+	}
+}
+
 void
 configcamera(Camera *c, Viewport *v, double fov, double n, double f, Projection p)
 {
@@ -132,29 +162,6 @@ aimcamera(Camera *c, Point3 focus)
 	placecamera(c, c->p, focus, c->by);
 }
 
-void
-reloadcamera(Camera *c)
-{
-	double a;
-	double l, r, b, t;
-
-	verifycfg(c);
-	switch(c->projtype){
-	case ORTHOGRAPHIC:
-		r = Dx(c->vp->fbctl->fb[0]->r)/2;
-		t = Dy(c->vp->fbctl->fb[0]->r)/2;
-		l = -r;
-		b = -t;
-		orthographic(c->proj, l, r, b, t, c->clip.n, c->clip.f);
-		break;
-	case PERSPECTIVE:
-		a = (double)Dx(c->vp->fbctl->fb[0]->r)/Dy(c->vp->fbctl->fb[0]->r);
-		perspective(c->proj, c->fov, a, c->clip.n, c->clip.f);
-		break;
-	default: sysfatal("unknown projection type");
-	}
-}
-
 void
 shootcamera(Camera *c, Shadertab *s)
 {
@@ -167,8 +174,9 @@ shootcamera(Camera *c, Shadertab *s)
 	job = emalloc(sizeof *job);
 	memset(job, 0, sizeof *job);
 	job->fb = c->vp->fbctl->getbb(c->vp->fbctl);
-	job->camera = c;
-	job->scene = c->scene;
+	job->camera = emalloc(sizeof *c);
+	*job->camera = *c;
+	job->scene = dupscene(c->scene);	/* take a snapshot */
 	job->shaders = s;
 	job->donec = chancreate(sizeof(void*), 0);
 
@@ -176,21 +184,23 @@ shootcamera(Camera *c, Shadertab *s)
 	t0 = nanosec();
 	sendp(c->rctl->c, job);
 	recvp(job->donec);
+	delscene(job->scene);			/* destroy the snapshot */
 	/*
 	 * if the scene has a skybox, do another render pass,
-	 * filling in the fragments left untouched by the z-buffer.
+	 * filling in the pixels left untouched.
 	 */
 	if(c->scene->skybox != nil){
 		if(skyboxscene == nil){
 			skyboxscene = newscene("skybox");
 			mdl = mkskyboxmodel();
-			skyboxscene->addent(skyboxscene, newentity(mdl));
+			skyboxscene->addent(skyboxscene, newentity("skybox", mdl));
 		}
 		skyboxscene->skybox = c->scene->skybox;
-		job->scene = skyboxscene;
+		job->scene = dupscene(skyboxscene);
 		job->shaders = &skyboxshader;
 		sendp(c->rctl->c, job);
 		recvp(job->donec);
+		delscene(job->scene);
 	}
 	t1 = nanosec();
 	c->vp->fbctl->swap(c->vp->fbctl);
@@ -199,5 +209,6 @@ shootcamera(Camera *c, Shadertab *s)
 	updatetimes(c, job);
 
 	chanfree(job->donec);
+	free(job->camera);
 	free(job);
 }
-- 
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