ref: 6477319da461ad78a120a3c777228eaa8194c9f8
parent: 3857a7ad606f4f050411d27fc94116731fddb1b3
author: rodri <rgl@antares-labs.eu>
date: Mon Jun 29 14:28:02 EDT 2020
bring flat triangle rasterization back, with some goodies for future shading work. add uv coordinates to the vertex.
--- a/camera.c
+++ b/camera.c
@@ -15,7 +15,7 @@
{assert(c->viewport != nil);
if(c->ptype == Ppersp)
- assert(c->fov > 0 && c->fov < 360);
+ assert(c->fov > 0 && c->fov < 360*DEG);
assert(c->clip.n > 0 && c->clip.n < c->clip.f);
}
--- a/graphics.h
+++ b/graphics.h
@@ -8,6 +8,7 @@
typedef struct Framebuffer Framebuffer;
typedef struct Viewport Viewport;
typedef struct Camera Camera;
+typedef struct Triangle Triangle;
struct Color
{@@ -19,6 +20,7 @@
Point3 p; /* position */
Point3 n; /* surface normal */
Color c; /* shading color */
+ Point2 uv; /* texture coordinate */
};
struct Framebuffer
@@ -47,6 +49,11 @@
Projection ptype;
};
+struct Triangle
+{+ Point p0, p1, p2;
+};
+
/* Camera */
void configcamera(Camera*, Image*, double, double, double, Projection);
void placecamera(Camera*, Point3, Point3, Point3);
@@ -64,5 +71,12 @@
Point2 fromviewport(Camera*, Point);
void perspective(Matrix3, double, double, double, double);
void orthographic(Matrix3, double, double, double, double, double, double);
+/* temporary debug helpers */
void line3(Camera*, Point3, Point3, int, int, Image*);
Point string3(Camera*, Point3, Image*, Font*, char*);
+
+/* triangle */
+Triangle Trian(int, int, int, int, int, int);
+Triangle Trianpt(Point, Point, Point);
+void triangle(Image*, Triangle, int, Image*, Point);
+void filltriangle(Image*, Triangle, Image*, Point);
--- a/mkfile
+++ b/mkfile
@@ -4,6 +4,7 @@
OFILES=\
camera.$O\
render.$O\
+ triangle.$O\
HFILES=graphics.h ../libgeometry/geometry.h
--- /dev/null
+++ b/triangle.c
@@ -1,0 +1,72 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include <geometry.h>
+#include <graphics.h>
+
+/*
+ * comparison of a point p with an edge [e0 e1]
+ * p to the right: +
+ * p to the left: -
+ * p on the edge: 0
+ */
+static int
+edgeptcmp(Point e0, Point e1, Point p)
+{+ Point3 e0p, e01, r;
+
+ p = subpt(p, e0);
+ e1 = subpt(e1, e0);
+ e0p = Vec3(p.x,p.y,0);
+ e01 = Vec3(e1.x,e1.y,0);
+ r = crossvec3(e0p, e01);
+
+ /* clamp to avoid overflow */
+ return fclamp(r.z, -1, 1); /* e0.x*e1.y - e0.y*e1.x */
+}
+
+Triangle
+Trian(int x0, int y0, int x1, int y1, int x2, int y2)
+{+ return (Triangle){Pt(x0, y0), Pt(x1, y1), Pt(x2, y2)};+}
+
+Triangle
+Trianpt(Point p0, Point p1, Point p2)
+{+ return (Triangle){p0, p1, p2};+};
+
+void
+triangle(Image *dst, Triangle t, int thick, Image *src, Point sp)
+{+ Point pl[4];
+
+ pl[0] = t.p0;
+ pl[1] = t.p1;
+ pl[2] = t.p2;
+ pl[3] = pl[0];
+
+ poly(dst, pl, nelem(pl), 0, 0, thick, src, sp);
+}
+
+void
+filltriangle(Image *dst, Triangle t, Image *src, Point sp)
+{+ Point pl[3];
+
+ pl[0] = t.p0;
+ pl[1] = t.p1;
+ pl[2] = t.p2;
+
+ fillpoly(dst, pl, nelem(pl), 0, src, sp);
+}
+
+int
+ptintriangle(Point p, Triangle t)
+{+ /* counter-clockwise check */
+ return edgeptcmp(t.p0, t.p2, p) <= 0 &&
+ edgeptcmp(t.p2, t.p1, p) <= 0 &&
+ edgeptcmp(t.p1, t.p0, p) <= 0;
+}