progs/trivial/flat-clip.c

   1 /**
   2  * Test flat shading and clipping.
   3  *
   4  * Brian Paul
   5  * 30 August 2007
   6  */
   7
   8
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <math.h>
  12 #include <GL/glut.h>
  13
  14 static int Win;
  15 static GLfloat Scale = 2.0, Zrot = 50;
  16 static GLenum Mode = GL_LINE_LOOP;
  17 static GLboolean Smooth = 0;
  18 static GLenum PolygonMode = GL_FILL;
  19
  20
  21 static void
  22 Draw(void)
  23 {
  24    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  25
  26    if (Smooth)
  27       glShadeModel(GL_SMOOTH);
  28    else
  29       glShadeModel(GL_FLAT);
  30
  31    glPushMatrix();
  32    glScalef(Scale, Scale, 1);
  33    glRotatef(Zrot, 0, 0, 1);
  34
  35    glPolygonMode(GL_FRONT_AND_BACK, PolygonMode);
  36
  37    glBegin(Mode);
  38    glColor3f(1, 0, 0);
  39    glVertex2f(-1, -1);
  40    glColor3f(0, 1, 0);
  41    glVertex2f( 2, -1);
  42    glColor3f(0, 0, 1);
  43    glVertex2f( 0, 1);
  44    glEnd();
  45
  46    glPushMatrix();
  47    glScalef(0.9, 0.9, 1);
  48    glBegin(Mode);
  49    glColor3f(1, 0, 0);
  50    glVertex2f( 0, 1);
  51
  52    glColor3f(0, 0, 1);
  53    glVertex2f( 2, -1);
  54
  55    glColor3f(0, 1, 0);
  56    glVertex2f(-1, -1);
  57
  58    glEnd();
  59    glPopMatrix();
  60
  61    glPopMatrix();
  62
  63    glutSwapBuffers();
  64 }
  65
  66
  67 static void
  68 Reshape(int width, int height)
  69 {
  70    glViewport(0, 0, width, height);
  71    glMatrixMode(GL_PROJECTION);
  72    glLoadIdentity();
  73    glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
  74    glMatrixMode(GL_MODELVIEW);
  75    glLoadIdentity();
  76    glTranslatef(0.0, 0.0, -15.0);
  77 }
  78
  79
  80 static void
  81 Key(unsigned char key, int x, int y)
  82 {
  83    (void) x;
  84    (void) y;
  85    switch (key) {
  86       case 'p':
  87          if (Mode == GL_TRIANGLES)
  88             Mode = GL_LINE_LOOP;
  89          else
  90             Mode = GL_TRIANGLES;
  91          break;
  92       case 'f':
  93          if (PolygonMode == GL_POINT)
  94             PolygonMode = GL_LINE;
  95          else if (PolygonMode == GL_LINE)
  96             PolygonMode = GL_FILL;
  97          else
  98             PolygonMode = GL_POINT;
  99          printf("PolygonMode = 0x%x\n", PolygonMode);
 100          break;
 101       case 'r':
 102          Zrot -= 5.0;
 103          break;
 104       case 'R':
 105          Zrot += 5.0;
 106          break;
 107       case 'z':
 108          Scale *= 1.1;
 109          break;
 110       case 'Z':
 111          Scale /= 1.1;
 112          break;
 113       case 's':
 114          Smooth = !Smooth;
 115          break;
 116       case 27:
 117          glutDestroyWindow(Win);
 118          exit(0);
 119          break;
 120    }
 121    glutPostRedisplay();
 122 }
 123
 124
 125 static void
 126 Init(void)
 127 {
 128    printf("Usage:\n");
 129    printf("  z/Z:  change triangle size\n");
 130    printf("  r/R:  rotate\n");
 131    printf("  p:    toggle line/fill mode\n");
 132    printf("  s:    toggle smooth/flat shading\n");
 133    printf("  f:    switch polygon fill mode\n");
 134 }
 135
 136
 137 int
 138 main(int argc, char *argv[])
 139 {
 140    glutInit(&argc, argv);
 141    glutInitWindowPosition(0, 0);
 142    glutInitWindowSize(400, 400);
 143    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 144    Win = glutCreateWindow(argv[0]);
 145    glutReshapeFunc(Reshape);
 146    glutKeyboardFunc(Key);
 147    glutDisplayFunc(Draw);
 148    Init();
 149    glutMainLoop();
 150    return 0;
 151 }