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Diffstat (limited to 'progs/xdemos/offset.c')
| -rw-r--r-- | progs/xdemos/offset.c | 323 |
1 files changed, 323 insertions, 0 deletions
diff --git a/progs/xdemos/offset.c b/progs/xdemos/offset.c new file mode 100644 index 0000000000..158e52a97c --- /dev/null +++ b/progs/xdemos/offset.c @@ -0,0 +1,323 @@ +/**************************************************************************** +Copyright 1995 by Silicon Graphics Incorporated, Mountain View, California. + + All Rights Reserved + +Permission to use, copy, modify, and distribute this software and its +documentation for any purpose and without fee is hereby granted, +provided that the above copyright notice appear in all copies and that +both that copyright notice and this permission notice appear in +supporting documentation, and that the name of Silicon Graphics not be +used in advertising or publicity pertaining to distribution of the +software without specific, written prior permission. + +SILICON GRAPHICS DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, +INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO +EVENT SHALL SILICON GRAPHICS BE LIABLE FOR ANY SPECIAL, INDIRECT OR +CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF +USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR +OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR +PERFORMANCE OF THIS SOFTWARE. + +****************************************************************************/ + +/* + * Derived from code written by Kurt Akeley, November 1992 + * + * Uses PolygonOffset to draw hidden-line images. PolygonOffset + * shifts the z values of polygons an amount that is + * proportional to their slope in screen z. This keeps + * the lines, which are drawn without displacement, from + * interacting with their respective polygons, and + * thus eliminates line dropouts. + * + * The left image shows an ordinary antialiased wireframe image. + * The center image shows an antialiased hidden-line image without + * PolygonOffset. + * The right image shows an antialiased hidden-line image using + * PolygonOffset to reduce artifacts. + * + * Drag with a mouse button pressed to rotate the models. + * Press the escape key to exit. + */ + +/* + * Modified for OpenGL 1.1 glPolygonOffset() conventions + */ + + +#include <GL/glx.h> +#include <GL/glu.h> +#include <X11/keysym.h> +#include <stdlib.h> +#include <stdio.h> +#include <string.h> + +/*#undef GL_EXT_polygon_offset uncomment to use new version*/ + + +#ifndef EXIT_FAILURE +# define EXIT_FAILURE 1 +#endif +#ifndef EXIT_SUCCESS +# define EXIT_SUCCESS 0 +#endif + +#define MAXQUAD 6 + +typedef float Vertex[3]; + +typedef Vertex Quad[4]; + +/* data to define the six faces of a unit cube */ +Quad quads[MAXQUAD] = { + { {0,0,0}, {1,0,0}, {1,1,0}, {0,1,0} }, + { {0,0,1}, {1,0,1}, {1,1,1}, {0,1,1} }, + { {0,0,0}, {1,0,0}, {1,0,1}, {0,0,1} }, + { {0,1,0}, {1,1,0}, {1,1,1}, {0,1,1} }, + { {0,0,0}, {0,0,1}, {0,1,1}, {0,1,0} }, + { {1,0,0}, {1,0,1}, {1,1,1}, {1,1,0} } +}; + +#define WIREFRAME 0 +#define HIDDEN_LINE 1 + +static void error(const char* prog, const char* msg); +static void cubes(int mx, int my, int mode); +static void fill(Quad quad); +static void outline(Quad quad); +static void draw_hidden(Quad quad, int mode); +static void process_input(Display *dpy, Window win); +static int query_extension(char* extName); + +static int attributeList[] = { GLX_RGBA, GLX_RED_SIZE, 1, GLX_GREEN_SIZE, 1, + GLX_BLUE_SIZE, 1, GLX_DOUBLEBUFFER, GLX_DEPTH_SIZE, 1, None }; + +static int dimension = 3; + +int main(int argc, char** argv) { + Display *dpy; + XVisualInfo *vi; + XSetWindowAttributes swa; + Window win; + GLXContext cx; + + dpy = XOpenDisplay(0); + if (!dpy) error(argv[0], "can't open display"); + + vi = glXChooseVisual(dpy, DefaultScreen(dpy), attributeList); + if (!vi) error(argv[0], "no suitable visual"); + + cx = glXCreateContext(dpy, vi, 0, GL_TRUE); + + swa.colormap = XCreateColormap(dpy, RootWindow(dpy, vi->screen), + vi->visual, AllocNone); + + swa.border_pixel = 0; + swa.event_mask = ExposureMask | StructureNotifyMask | KeyPressMask | + ButtonPressMask | ButtonMotionMask; + win = XCreateWindow(dpy, RootWindow(dpy, vi->screen), 0, 0, 900, 300, + 0, vi->depth, InputOutput, vi->visual, + CWBorderPixel|CWColormap|CWEventMask, &swa); + XStoreName(dpy, win, "hiddenline"); + XMapWindow(dpy, win); + + glXMakeCurrent(dpy, win, cx); + + /* check for the polygon offset extension */ +#ifndef GL_VERSION_1_1 + if (!query_extension("GL_EXT_polygon_offset")) + error(argv[0], "polygon_offset extension is not available"); +#else + (void) query_extension; +#endif + + /* set up viewing parameters */ + glMatrixMode(GL_PROJECTION); + gluPerspective(20, 1, 0.1, 20); + glMatrixMode(GL_MODELVIEW); + glTranslatef(0, 0, -15); + + /* set other relevant state information */ + glEnable(GL_DEPTH_TEST); + +#ifdef GL_EXT_polygon_offset + printf("using 1.0 offset extension\n"); + glPolygonOffsetEXT( 1.0, 0.00001 ); +#else + printf("using 1.1 offset\n"); + glPolygonOffset( 1.0, 0.5 ); +#endif + + glShadeModel( GL_FLAT ); + glDisable( GL_DITHER ); + + /* process events until the user presses ESC */ + while (1) process_input(dpy, win); + + return 0; +} + +static void +draw_scene(int mx, int my) { + glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); + + glPushMatrix(); + glTranslatef(-1.7, 0.0, 0.0); + cubes(mx, my, WIREFRAME); + glPopMatrix(); + + glPushMatrix(); + cubes(mx, my, HIDDEN_LINE); + glPopMatrix(); + + glPushMatrix(); + glTranslatef(1.7, 0.0, 0.0); +#ifdef GL_EXT_polygon_offset + glEnable(GL_POLYGON_OFFSET_EXT); +#else + glEnable(GL_POLYGON_OFFSET_FILL); +#endif + cubes(mx, my, HIDDEN_LINE); +#ifdef GL_EXT_polygon_offset + glDisable(GL_POLYGON_OFFSET_EXT); +#else + glDisable(GL_POLYGON_OFFSET_FILL); +#endif + glPopMatrix(); +} + + +static void +cubes(int mx, int my, int mode) { + int x, y, z, i; + + /* track the mouse */ + glRotatef(mx / 2.0, 0, 1, 0); + glRotatef(my / 2.0, 1, 0, 0); + + /* draw the lines as hidden polygons */ + glTranslatef(-0.5, -0.5, -0.5); + glScalef(1.0/dimension, 1.0/dimension, 1.0/dimension); + for (z = 0; z < dimension; z++) { + for (y = 0; y < dimension; y++) { + for (x = 0; x < dimension; x++) { + glPushMatrix(); + glTranslatef(x, y, z); + glScalef(0.8, 0.8, 0.8); + for (i = 0; i < MAXQUAD; i++) + draw_hidden(quads[i], mode); + glPopMatrix(); + } + } + } +} + +static void +fill(Quad quad) { + /* draw a filled polygon */ + glBegin(GL_QUADS); + glVertex3fv(quad[0]); + glVertex3fv(quad[1]); + glVertex3fv(quad[2]); + glVertex3fv(quad[3]); + glEnd(); +} + +static void +outline(Quad quad) { + /* draw an outlined polygon */ + glBegin(GL_LINE_LOOP); + glVertex3fv(quad[0]); + glVertex3fv(quad[1]); + glVertex3fv(quad[2]); + glVertex3fv(quad[3]); + glEnd(); +} + +static void +draw_hidden(Quad quad, int mode) { + if (mode == HIDDEN_LINE) { + glColor3f(0, 0, 0); + fill(quad); + } + + /* draw the outline using white, optionally fill the interior with black */ + glColor3f(1, 1, 1); + outline(quad); +} + +static void +process_input(Display *dpy, Window win) { + XEvent event; + static int prevx, prevy; + static int deltax = 90, deltay = 40; + + do { + char buf[31]; + KeySym keysym; + + XNextEvent(dpy, &event); + switch(event.type) { + case Expose: + break; + case ConfigureNotify: { + /* this approach preserves a 1:1 viewport aspect ratio */ + int vX, vY, vW, vH; + int eW = event.xconfigure.width, eH = event.xconfigure.height; + if (eW >= eH) { + vX = 0; + vY = (eH - eW) >> 1; + vW = vH = eW; + } else { + vX = (eW - eH) >> 1; + vY = 0; + vW = vH = eH; + } + glViewport(vX, vY, vW, vH); + } + break; + case KeyPress: + (void) XLookupString(&event.xkey, buf, sizeof(buf), &keysym, NULL); + switch (keysym) { + case XK_Escape: + exit(EXIT_SUCCESS); + default: + break; + } + case ButtonPress: + prevx = event.xbutton.x; + prevy = event.xbutton.y; + break; + case MotionNotify: + deltax += (event.xbutton.x - prevx); prevx = event.xbutton.x; + deltay += (event.xbutton.y - prevy); prevy = event.xbutton.y; + break; + default: + break; + } + } while (XPending(dpy)); + + draw_scene(deltax, deltay); + glXSwapBuffers(dpy, win); +} + +static void +error(const char *prog, const char *msg) { + fprintf(stderr, "%s: %s\n", prog, msg); + exit(EXIT_FAILURE); +} + +static int +query_extension(char* extName) { + char *p = (char *) glGetString(GL_EXTENSIONS); + char *end = p + strlen(p); + while (p < end) { + int n = strcspn(p, " "); + if ((strlen(extName) == n) && (strncmp(extName, p, n) == 0)) + return GL_TRUE; + p += (n + 1); + } + return GL_FALSE; +} + |