From d3516b11559657935d70829c672f29393e857b8e Mon Sep 17 00:00:00 2001
From: rodri <rgl@antares-labs.eu>
Date: Mon, 20 May 2024 20:20:48 +0000
Subject: fix the perspective projection and add inverse xform functions.

---
 render.c | 112 ---------------------------------------------------------------
 1 file changed, 112 deletions(-)

(limited to 'render.c')

diff --git a/render.c b/render.c
index 88e74c2..f0fffd7 100644
--- a/render.c
+++ b/render.c
@@ -52,118 +52,6 @@ isfacingback(Primitive p)
 	return sa <= 0;
 }
 
-/*
- * transforms p from e's reference frame into
- * the world.
- */
-Point3
-model2world(Entity *e, Point3 p)
-{
-	return invrframexform3(p, *e);
-}
-
-/*
- * transforms p from the world reference frame
- * to c's one (aka Viewing Coordinate System).
- */
-Point3
-world2vcs(Camera *c, Point3 p)
-{
-	return rframexform3(p, *c);
-}
-
-/*
- * projects p from the VCS to clip space, placing
- * p.[xyz] ∈ (-∞,-w)∪[-w,w]∪(w,∞) where [-w,w]
- * represents the visibility volume.
- *
- * the clipping planes are:
- *
- * 	|   -w   |   w   |
- *	+----------------+
- * 	| left   | right |
- * 	| bottom | top   |
- * 	| far    | near  |
- */
-Point3
-vcs2clip(Camera *c, Point3 p)
-{
-	return xform3(p, c->proj);
-}
-
-Point3
-world2clip(Camera *c, Point3 p)
-{
-	return vcs2clip(c, world2vcs(c, p));
-}
-
-/*
- * performs the perspective division, placing
- * p.[xyz] ∈ [-1,1] and p.w = 1/z
- * (aka Normalized Device Coordinates).
- *
- * p.w is kept as z⁻¹ so we can later do
- * perspective-correct attribute interpolation.
- */
-static Point3
-clip2ndc(Point3 p)
-{
-	p.w = p.w == 0? 1: 1.0/p.w;
-	p.x *= p.w;
-	p.y *= p.w;
-	p.z *= p.w;
-	return p;
-}
-
-/*
- * scales p to fit the destination viewport,
- * placing p.x ∈ [0,width], p.y ∈ [0,height],
- * p.z ∈ [0,1] and leaving p.w intact.
- */
-static Point3
-ndc2viewport(Framebuf *fb, Point3 p)
-{
-	Matrix3 view = {
-		Dx(fb->r)/2.0,             0,       0,       Dx(fb->r)/2.0,
-		0,            -Dy(fb->r)/2.0,       0,       Dy(fb->r)/2.0,
-		0,                         0, 1.0/2.0,             1.0/2.0,
-		0,                         0,       0,                   1,
-	};
-	double w;
-
-	w = p.w;
-	p.w = 1;
-	p = xform3(p, view);
-	p.w = w;
-	return p;
-}
-
-void
-perspective(Matrix3 m, double fov, double a, double n, double f)
-{
-	double cotan;
-
-	cotan = 1/tan(fov/2);
-	identity3(m);
-	m[0][0] =  cotan/a;
-	m[1][1] =  cotan;
-	m[2][2] =  (f+n)/(f-n);
-	m[2][3] = -2*f*n/(f-n);
-	m[3][2] = -1;
-}
-
-void
-orthographic(Matrix3 m, double l, double r, double b, double t, double n, double f)
-{
-	identity3(m);
-	m[0][0] =  2/(r - l);
-	m[1][1] =  2/(t - b);
-	m[2][2] = -2/(f - n);
-	m[0][3] = -(r + l)/(r - l);
-	m[1][3] = -(t + b)/(t - b);
-	m[2][3] = -(f + n)/(f - n);
-}
-
 static void
 rasterize(Rastertask *task)
 {
-- 
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