/* ====================================================================== mount.c Ernie Wright 02 Jun 05 This version has been modified to fit your TV. ====================================================================== */ /* * mount.c - creates a fractal mountain, using Carpenter's method with a * different extension to square grids. A pyramid of 4 glass spheres * is added in front of the mountain. One light source. * * NOTE: the hashing function used to generate the database originally is * faulty. The function causes repetition to occur within the fractal * mountain (obviously not very fractal behavior!). A new hashing * function is included immediately after the old one: merely define * NEW_HASH if you want to use a better hashing function. To perform ray * tracing comparison tests you should still use the old, faulty database * (it may have repetition, but it's still a good test image). * * Author: Eric Haines * * size_factor determines the number of objects output. * Total triangular polygons = 2 * (4**size_factor) * * size_factor # triangles # spheres * 1 8 4 * 2 32 4 * 3 128 4 * * 6 8192 4 */ #include #include #include "lwmod.h" #include "def.h" #include "lib.h" static int size_factor = 6; static int output_format = 0; static char *spdName = "Mountain"; /* to use a much better hashing function, uncomment this next line */ #define JENKINS_HASH /* fractal dimension - affects variance of z. Between 2 and 3 */ #define FRACTAL_DIMENSION 2.2 /* change MOUNTAIN_NO to get a different mountain */ #define MOUNTAIN_NO 21 /* lower left corner and width of mountain definitions */ #define X_CORNER -1.0 #define Y_CORNER -1.0 #define WIDTH 2.0 #ifndef JENKINS_HASH /* Hashing function to get a seed for the random number generator. */ /* This is the old, buggy hashing function - use it if you wish to * obtain the same image as in the November 1987 IEEE CG&A article. */ #define hash_rand(A,B,C) ( ( (((unsigned long)(A))<<(23-(C))) + \ (((unsigned long)(B))<<(15-(C))) \ + (((unsigned long)(A))<<(7-(C))) ) & 0xffff) #else /* * Bob Jenkins invented this great, reasonably fast, very nice * has function. Check out his web page: * http://ourworld.compuserve.com/homepages/bob_jenkins/blockcip.htm */ #define mix(a,b,c) \ { \ a -= b; a -= c; a ^= (c>>13); \ b -= c; b -= a; b ^= (a<<8); \ c -= a; c -= b; c ^= (b>>13); \ a -= b; a -= c; a ^= (c>>12); \ b -= c; b -= a; b ^= (a<<16); \ c -= a; c -= b; c ^= (b>>5); \ a -= b; a -= c; a ^= (c>>3); \ b -= c; b -= a; b ^= (a<<10); \ c -= a; c -= b; c ^= (b>>15); \ } int hash_rand(int A, int B, int C) { mix(A,B,C) ; return C & 0xffff ; } #endif static double Roughness ; /* create a pyramid of crystal spheres */ static void create_spheres(center) COORD4 center; { int i; double angle; COORD3 axis, pt, new_pt; COORD4 sphere; MATRIX mx; SET_COORD3(axis, 1.0, 1.0, 0.0); (void)lib_normalize_vector(axis); angle = acos((double)(-1.0/3.0)); /* set center of pyramid */ SET_COORD3(pt, 0.0, 0.0, center[W] * sqrt((double)(3.0/2.0))); COPY_COORD4(sphere, center); ADD2_COORD3(sphere, pt); lib_output_sphere(sphere, output_format); lib_create_axis_rotate_matrix(mx, axis, angle); lib_transform_vector(new_pt, pt, mx); for (i = 0; i < 3; i++) { lib_create_rotate_matrix(mx, Z_AXIS, (double)i * 2.0 * PI / 3.0); lib_transform_vector(sphere, new_pt, mx); ADD2_COORD3(sphere, center); lib_output_sphere(sphere, output_format); } } /* * Build mountain section. If at width > 1, split quadrilateral into four * parts. Else if at width == 1, output quadrilateral as two triangles. */ static void grow_mountain(fnum_pts, width, ll_x, ll_y, ll_fz, lr_fz, ur_fz, ul_fz) double fnum_pts; int width; int ll_x; int ll_y ; double ll_fz; double lr_fz; double ur_fz; double ul_fz; { long iz; int half_width, num_tri, num_tri_vert, num_vert; double l_fx, r_fx, l_fy, u_fy; double lower_fz, right_fz, upper_fz, left_fz, middle_fz; double rise_height, hside_length; COORD3 tri_vert[3]; if ( width == 1 ) { /* calculate x and y coordinates of corners */ l_fx = X_CORNER + (double)ll_x * WIDTH / fnum_pts; r_fx = X_CORNER + (double)(ll_x+1) * WIDTH / fnum_pts; l_fy = Y_CORNER + (double)ll_y * WIDTH / fnum_pts; u_fy = Y_CORNER + (double)(ll_y+1) * WIDTH / fnum_pts; /* output two triangles for section */ for (num_tri = 0; num_tri < 2; num_tri++) { for (num_vert = 0; num_vert < 3; num_vert++) { num_tri_vert = (num_vert + num_tri * 2) % 4; switch (num_tri_vert) { case 0: SET_COORD3(tri_vert[num_vert], l_fx, l_fy, ll_fz); break; case 1: SET_COORD3(tri_vert[num_vert], r_fx, l_fy, lr_fz); break; case 2: SET_COORD3(tri_vert[num_vert], r_fx, u_fy, ur_fz); break; case 3: SET_COORD3(tri_vert[num_vert], l_fx, u_fy, ul_fz); break; } } lib_output_polygon(3, tri_vert); } } else { /* subdivide edges and move in z direction */ half_width = width>>1; hside_length = (double)half_width * WIDTH / fnum_pts; rise_height = hside_length * Roughness; /* for each midpoint, find z */ iz = MOUNTAIN_NO + hash_rand(ll_x + half_width, ll_y, size_factor); lower_fz = (ll_fz + lr_fz) / 2.0 + rise_height * lib_gauss_rand(iz); iz = MOUNTAIN_NO + hash_rand(ll_x + width, ll_y + half_width, size_factor); right_fz = ( lr_fz + ur_fz ) / 2.0 + rise_height * lib_gauss_rand(iz); iz = MOUNTAIN_NO + hash_rand(ll_x + half_width, ll_y + width, size_factor); upper_fz = ( ur_fz + ul_fz ) / 2.0 + rise_height * lib_gauss_rand(iz); iz = MOUNTAIN_NO + hash_rand( ll_x, ll_y + half_width, size_factor); left_fz = ( ul_fz + ll_fz ) / 2.0 + rise_height * lib_gauss_rand(iz); iz = MOUNTAIN_NO + hash_rand(ll_x + half_width, ll_y + half_width, size_factor); middle_fz = ( ll_fz + lr_fz + ur_fz + ul_fz ) / 4.0 + 1.4142136 * rise_height * lib_gauss_rand(iz); /* check subsections for subdivision or output */ grow_mountain(fnum_pts, half_width, ll_x, ll_y, ll_fz, lower_fz, middle_fz, left_fz); if (width == 1<