Graphics assignment 11

Finished the complete assignment.

graphics/ass11/bsp.c

@@ -5,14 +5,10 @@
  * Date ............ 23.11.2009
  * Created by ...... Paul Melis
  *
- * Student name ....
- * Student email ...
- * Collegekaart ....
- * Date ............
- * Comments ........
- *
- *
- * (always fill in these fields before submitting!!)
+ * Student name .... Sander van Veen & Taddeus Kroes
+ * Student email ... sandervv@gmail.com & taddeuskroes@hotmail.com
+ * Collegekaart .... 6169676 & 6054129
+ * Date ............ 01.12.2010
  */
 
 #include <stdlib.h>
@@ -20,6 +16,8 @@
 #include <assert.h>
 #include "bsp.h"
 
+#define DOTPROD_TRESHOLD 1e-3
+
 /* Given a list of polygons builds a BSP tree by recursively choosing
  * one polygon that defines a split plane and dividing the other polygons
  * arbitrarily into left and right subsets. This does NOT result in a
@@ -135,6 +133,37 @@ void
 split_triangle_one_edge_intersection(polys *left_polygons, polys *right_polygons,
     vec3 plane_p, vec3 plane_n, poly p, int *side, int in_plane)
 {
+	// Indices to the other vertices, vl is the one left of
+	// the split plane and vr is the one on the right
+	int vl = (in_plane + 1) % 3, vr = (in_plane + 2) % 3, temp;
+	float t;
+	poly p2 = p;
+	
+	// Swap vl and vr if vl is on the right of the split plane
+	if( side[vl] == 1 )
+	{
+		temp = vl;
+		vl = vr;
+		vr = temp;
+	}
+	
+	// Find the intersection
+	if( !check_for_intersection(&t, plane_p, plane_n, p.pts[vl], p.pts[vr]) )
+	{
+		puts("Plane does not go through the vertices");
+		exit(1);
+	}
+	
+	// Change one vertex of each triangle to the intersection on the plane,
+	// do the same for the texture coordinates of these vertices
+	p2.pts[vl] = p.pts[vr] =
+		v3_add(v3_multiply(p.pts[vl], 1-t), v3_multiply(p.pts[vr], t));
+	p2.tcoord[vl] = p.tcoord[vr] =
+		v3_add(v3_multiply(p.tcoord[vl], 1-t), v3_multiply(p.tcoord[vr], t));
+	
+	// The triangle with vl should be on the left of the plane
+	AddPolyToPolylist(left_polygons, p);
+	AddPolyToPolylist(right_polygons, p2);
 }
 
 /* Triangle 'p' is known to intersect the plane defined
@@ -156,6 +185,45 @@ void
 split_triangle_two_edge_intersections(polys *left_polygons, polys *right_polygons,
     vec3 plane_p, vec3 plane_n, poly p, int *side, int single)
 {
+	// Indices to the other vertices
+	int v1 = (single + 1) % 3, v2 = (single + 2) % 3;
+	float t1, t2;
+	poly p2 = p, p3 = p;
+
+	// Find intersection points
+	if( !check_for_intersection(&t1, plane_p, plane_n, p.pts[single], p.pts[v1])
+	    || !check_for_intersection(&t2, plane_p, plane_n, p.pts[single], p.pts[v2]) )
+	{
+		puts("Plane does not go through both edges");
+		exit(1);
+	}
+	
+	// Change the vertices of the triangles so that there's no overlap and
+	// p is on the opposite side of the plane as p2 and p3. Do the same for
+	// the texture coordinates
+	p.pts[v1] = p3.pts[v1] = p2.pts[single] =
+		v3_add(v3_multiply(p.pts[single], 1-t1), v3_multiply(p.pts[v1], t1));
+	p.pts[v2] = p3.pts[single] =
+		v3_add(v3_multiply(p.pts[single], 1-t2), v3_multiply(p.pts[v2], t2));
+
+	p.tcoord[v1] = p3.tcoord[v1] = p2.tcoord[single] =
+		v3_add(v3_multiply(p.tcoord[single], 1-t1), v3_multiply(p.tcoord[v1], t1));
+	p.tcoord[v2] = p3.tcoord[single] =
+		v3_add(v3_multiply(p.tcoord[single], 1-t2), v3_multiply(p.tcoord[v2], t2));
+	
+	// As said, p is on the opposite side as p2 and p3
+	if( side[single] == -1 )
+	{
+		AddPolyToPolylist(left_polygons, p);
+		AddPolyToPolylist(right_polygons, p2);
+		AddPolyToPolylist(right_polygons, p3);
+	}
+	else
+	{
+		AddPolyToPolylist(right_polygons, p);
+		AddPolyToPolylist(left_polygons, p2);
+		AddPolyToPolylist(left_polygons, p3);
+	}
 }
 
 /* Polygon 'p' (a triangle) is known to straddle the plane defined by
@@ -173,6 +241,20 @@ void
 split_triangle(polys *left_polygons, polys *right_polygons,
     vec3 plane_p, vec3 plane_n, poly p, int *side)
 {
+	for( int i = 0; i < 3; i++ )
+	{
+		if( !side[i] )
+		{
+			// Vertex found on plane, there's one intersection
+			split_triangle_one_edge_intersection(left_polygons, right_polygons,
+				plane_p, plane_n, p, side, i);
+			return;
+		}
+	}
+
+	// No vertex found on plane, there are two intersections
+	split_triangle_two_edge_intersections(left_polygons, right_polygons, plane_p,
+		plane_n, p, side, side[0] == side[1] ? 2 : (side[1] == side[2] ? 0 : 1));
 }
 
 /*
@@ -183,5 +265,74 @@ split_triangle(polys *left_polygons, polys *right_polygons,
 BSPNode*
 BuildBSPTree(polys *polygons)
 {
-}
+    polys *left_polygons, *right_polygons;
+    BSPNode *left_tree, *right_tree;
+    BSPNode *root;
+    poly split_poly, p;
+	float dot;
+	vec3 plane_p, plane_n;
+	int side[MAX_VERTICES], i, j, left, right;
+
+    // Arbitrary initial capacity for the lists, they will grow as
+    // needed automatically
+    left_polygons = CreatePolylist(4);
+    right_polygons = CreatePolylist(4);
+
+    // Pick a polygon which defines the split plane
+    split_poly = polygons->items[0];
+	plane_p = split_poly.pts[0];
+	plane_n = split_poly.normal[0];
+
+    // Sort the remaining polygons in seperate trees, one left and one right of
+	// the split plane. We'll assume that all polygons are triangles
+	for( i = 1; i < polygons->length; i++ )
+    {
+		p = polygons->items[i];
+		left = right = 0;
+
+		// Classify vertices
+		for( j = 0; j < p.points; j++ )
+		{
+			dot = v3_dotprod(v3_subtract(p.pts[j], plane_p), plane_n);
+			
+			if( dot > DOTPROD_TRESHOLD )
+			{
+				side[j] = -1; // Left
+				left++;
+			}
+			else if( dot < -DOTPROD_TRESHOLD )
+			{
+				side[j] = 1; // Right
+				right++;
+			}
+			else
+				side[j] = 0; // On
+		}
+
+		// Classify triangle
+		if( !right )
+			AddPolyToPolylist(left_polygons, p); // Left
+		else if( !left )
+			AddPolyToPolylist(right_polygons, p); // Right
+		else
+			split_triangle(left_polygons, right_polygons, plane_p, plane_n, p, side); // Straddling
+    }
 
+    // Recursively subdivide the left and right lists
+	left_tree = left_polygons->length ? BuildBSPTree(left_polygons) : NULL;
+	right_tree = right_polygons->length ? BuildBSPTree(right_polygons) : NULL;
+
+    // We can free the child polygon lists, as each child polygon
+    // will now have been stored in a BSP node
+    DestroyPolylist(left_polygons);
+    DestroyPolylist(right_polygons);
+
+    // Create tree node and return it
+    root = (BSPNode*) malloc(sizeof(BSPNode));
+
+    root->polygon = split_poly;
+    root->left_child = left_tree;
+    root->right_child = right_tree;
+
+    return root;
+}

graphics/ass11/main.c

@@ -3,14 +3,10 @@
  * Date ............ 23.11.2009
  * Created by ...... Paul Melis
  *
- * Student name ....
- * Student email ...
- * Collegekaart ....
- * Date ............
- * Comments ........
- *
- *
- * (always fill in these fields before submitting!!)
+ * Student name .... Sander van Veen & Taddeus Kroes
+ * Student email ... sandervv@gmail.com & taddeuskroes@hotmail.com
+ * Collegekaart .... 6169676 & 6054129
+ * Date ............ 01.12.2010
  */
 
 #if defined(__GNUC__)
@@ -137,15 +133,12 @@ InitializePolygonlists(void)
         1.0, 0.0, 0.0, 0.0);
     AppendPolylist(scene_polygons, model_polygons);
 
-#if 0
     // Tree
     ClearPolylist(model_polygons);
     loadPolygonalObject(model_polygons, "tree.obj", texture_names, num_textures,
         0.6, 5.0, 16.0, 0.0);
     AppendPolylist(scene_polygons, model_polygons);
-#endif
 
-#if 0
     // Fish bowl
     ClearPolylist(model_polygons);
     loadPolygonalObject(model_polygons, "fishbowl.obj", texture_names, num_textures,
@@ -157,23 +150,18 @@ InitializePolygonlists(void)
     loadPolygonalObject(model_polygons, "goldfish.obj", texture_names, num_textures,
         1.0, 0.0, 0.0, 0.0);
     AppendPolylist(scene_polygons, model_polygons);
-#endif
 
-#if 0
     // Fence
     ClearPolylist(model_polygons);
     loadPolygonalObject(model_polygons, "hek.obj", texture_names, num_textures,
         1.0, 0.0, 0.0, 0.0);
     AppendPolylist(scene_polygons, model_polygons);
-#endif
 
-#if 0
     // A transparent cow (moooh!)
     ClearPolylist(model_polygons);
     loadPolygonalObject(model_polygons, "cow.obj", texture_names, num_textures,
         10.0, -3.0, -15.0, 0.0);
     AppendPolylist(scene_polygons, model_polygons);
-#endif
 
     // The skydome
     polylistSkydome = CreatePolylist(1000);
@@ -240,8 +228,7 @@ InitializePolygonlists(void)
     printf("%d transparent polygons\n", scene_transparent_polygons->length);
 
     // Build BSP tree
-
-    bsp_root = BuildBSPTreeIncorrect(scene_transparent_polygons);
+    bsp_root = BuildBSPTree(scene_transparent_polygons);
 }
 
 void
@@ -418,9 +405,32 @@ DrawPolylist(polys * list)
 void
 DrawBSPTree(BSPNode *node, vec3 eye_position)
 {
+	// Check if the tree is empty
+	if( !node )
+		return;
+	
+	BSPNode *first, *last;
+	poly p = node->polygon;
+
+	// Check if the eye position is on the left or right side of the polygon
+	if( v3_dotprod(v3_subtract(eye_position, p.pts[0]), p.normal[0]) > 0 )
+	{
+		first = node->right_child;
+		last = node->left_child;
+	}
+	else
+	{
+		first = node->left_child;
+		last = node->right_child;
+	}
+
+	// Draw the tree on the other side of the polygon from the eye point, then
+	// the polygon itself and finally the tree on the same side of the polygon
+	DrawBSPTree(first, eye_position);
+	DrawPolygon(p);
+	DrawBSPTree(last, eye_position);
 }
 
-
 void
 SetupCamera(void)
 {