- Added graphics assignment 9.

graphics/ass9/source/Makefile

+CC=gcc
+
+WARNING_FLAGS=-Wall -Wextra -Werror-implicit-function-declaration -Wshadow -Wstrict-prototypes -pedantic-errors
+CFLAGS=-g -O2 -std=c99 $(WARNING_FLAGS)
+LDFLAGS=-g -lGL -lglut -lGLU
+
+.c.o:
+	$(CC) -c $(CFLAGS) $<
+
+all: main
+main: main.o marching_tetrahedra.o volume.o
+	$(CC) $(LDFLAGS) -o main main.o marching_tetrahedra.o volume.o
+
+clean:
+	rm -f *.o
+	rm -f main
+
+volume.o              : v3math.h volume.h
+volume.o              : volume.h volume.c
+v3math.o              : v3math.h
+marching_tetrahedra.o : marching_tetrahedra.h marching_tetrahedra.c
+marching_tetrahedra.o : v3math.h volume.h marching_tetrahedra.h
+main.o                : marching_tetrahedra.h v3math.h volume.h main.c

graphics/ass9/source/marching_tetrahedra.c

+/* Computer Graphics, Assignment, Volume rendering with cubes/points/isosurface
+ *
+ * Student name ....
+ * Student email ...
+ * Collegekaart ....
+ * Date ............
+ * Comments ........
+ *
+ * (always fill in these fields before submitting!!)
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <assert.h>
+#include "marching_tetrahedra.h"
+
+/* Compute a linearly interpolated position where an isosurface cuts
+   an edge between two vertices (p1 and p2), each with their own
+   scalar value (v1 and v2) */
+
+static vec3
+interpolate_points(unsigned char isovalue, vec3 p1, vec3 p2,
+	unsigned char v1, unsigned char v2)
+{
+    /* Initially, simply return the midpoint between p1 and p2.
+       So no real interpolation is done yet */
+
+    return v3_add(v3_multiply(p1, 0.5), v3_multiply(p2, 0.5));
+}
+
+/* Using the given iso-value generate triangles for the tetrahedron
+   defined by corner vertices v0, v1, v2, v3 of cell c.
+
+   Store the resulting triangles in the "triangles" array.
+
+   Return the number of triangles created (either 0, 1, or 2).
+
+   Note: the output array "triangles" should have space for at least
+         2 triangles.
+*/
+
+static int
+generate_tetrahedron_triangles(triangle *triangles, unsigned char isovalue,
+	cell c, int v0, int v1, int v2, int v3)
+{
+    unsigned char *v = c.value;
+	vec3 *p = triangles[0].p;
+	int bitsystem = 0;
+	
+	if(c.value[v0] > isovalue) bitsystem += 1;
+    if(c.value[v1] > isovalue) bitsystem += 2;
+    if(c.value[v2] > isovalue) bitsystem += 4;
+    if(c.value[v3] > isovalue) bitsystem += 8;
+	
+	switch( bitsystem )
+	{
+	case 1: case 14: // 0001
+		p[0] = interpolate_points(isovalue, c.p[v0], c.p[v1], v[v0], v[v1]);
+		p[1] = interpolate_points(isovalue, c.p[v0], c.p[v2], v[v0], v[v2]);
+		p[2] = interpolate_points(isovalue, c.p[v0], c.p[v3], v[v0], v[v3]);
+		return 1;
+	case 2: case 13: // 0010
+		p[0] = interpolate_points(isovalue, c.p[v1], c.p[v0], v[v1], v[v0]);
+		p[1] = interpolate_points(isovalue, c.p[v1], c.p[v3], v[v1], v[v3]);
+		p[2] = interpolate_points(isovalue, c.p[v1], c.p[v2], v[v1], v[v2]);
+		return 1;
+	case 4: case 11: // 0100
+		p[0] = interpolate_points(isovalue, c.p[v2], c.p[v0], v[v2], v[v0]);
+		p[1] = interpolate_points(isovalue, c.p[v2], c.p[v1], v[v2], v[v1]);
+		p[2] = interpolate_points(isovalue, c.p[v2], c.p[v3], v[v2], v[v3]);
+		return 1;
+	case 8: case 7: // 1000
+		p[0] = interpolate_points(isovalue, c.p[v3], c.p[v0], v[v3], v[v0]);
+		p[1] = interpolate_points(isovalue, c.p[v3], c.p[v2], v[v3], v[v2]);
+		p[2] = interpolate_points(isovalue, c.p[v3], c.p[v1], v[v3], v[v1]);
+		return 1;
+	case 5: case 10: // 0101
+		p[0] = interpolate_points(isovalue, c.p[v0], c.p[v1], v[v0], v[v1]);
+		p[1] = interpolate_points(isovalue, c.p[v2], c.p[v3], v[v2], v[v3]);
+		p[2] = interpolate_points(isovalue, c.p[v0], c.p[v3], v[v0], v[v3]);
+		p = triangles[1].p;
+		p[0] = interpolate_points(isovalue, c.p[v0], c.p[v1], v[v0], v[v1]);
+		p[1] = interpolate_points(isovalue, c.p[v1], c.p[v2], v[v1], v[v2]);
+		p[2] = interpolate_points(isovalue, c.p[v2], c.p[v3], v[v2], v[v3]);
+		return 2;
+	case 3: case 12: // 0011
+		p[0] = interpolate_points(isovalue, c.p[v0], c.p[v3], v[v0], v[v3]);
+		p[1] = interpolate_points(isovalue, c.p[v0], c.p[v2], v[v0], v[v2]);
+		p[2] = interpolate_points(isovalue, c.p[v1], c.p[v3], v[v1], v[v3]);
+		p = triangles[1].p;
+		p[0] = interpolate_points(isovalue, c.p[v1], c.p[v3], v[v1], v[v3]);
+		p[2] = interpolate_points(isovalue, c.p[v1], c.p[v2], v[v1], v[v2]);
+		p[1] = interpolate_points(isovalue, c.p[v0], c.p[v2], v[v0], v[v2]);
+		return 2;
+	case 6: case 9: // 0110
+		p[0] = interpolate_points(isovalue, c.p[v0], c.p[v1], v[v0], v[v1]);
+		p[2] = interpolate_points(isovalue, c.p[v1], c.p[v3], v[v1], v[v3]);
+		p[1] = interpolate_points(isovalue, c.p[v2], c.p[v3], v[v2], v[v3]);
+		p = triangles[1].p;
+		p[0] = interpolate_points(isovalue, c.p[v0], c.p[v1], v[v0], v[v1]);
+		p[1] = interpolate_points(isovalue, c.p[v0], c.p[v2], v[v0], v[v2]);
+		p[2] = interpolate_points(isovalue, c.p[v2], c.p[v3], v[v2], v[v3]);
+		return 2;
+	default: // 0000
+		return 0;
+	}
+}
+
+/* Generate triangles for a single cell for the given iso-value. This function
+   should produce at most 6 * 2 triangles (for which the "triangles" array
+   should have enough space).
+
+   Use calls to generate_tetrahedron_triangles().
+
+   Return the number of triangles produced
+*/
+
+int
+generate_cell_triangles(triangle *triangles, cell c, unsigned char isovalue)
+{
+    const int points[24] = {0,1,3,7,0,2,6,7,0,1,5,7,0,2,3,7,0,4,5,7,0,4,6,7};
+	int i, tri_count = 0;
+
+	for( i = 0; i < 21; i += 4 )
+	{
+		tri_count += generate_tetrahedron_triangles(triangles + tri_count,
+			isovalue, c, points[i], points[i+1], points[i+2], points[i+3]);
+	}
+
+    return tri_count;
+}

graphics/ass9/source/marching_tetrahedra.h

+#ifndef MARCHING_TETRAHEDRA_H
+#define MARCHING_TETRAHEDRA_H
+
+#include "v3math.h"
+#include "volume.h"
+
+typedef struct
+{
+    vec3    p[3];
+    vec3    n[3];
+}
+triangle;
+
+int generate_cell_triangles(triangle *triangles, cell c, unsigned char isovalue);
+
+#endif