progs/glsl/brick.c

   1 /**
   2  * "Brick" shader demo.  Uses the example shaders from chapter 6 of
   3  * the OpenGL Shading Language "orange" book.
   4  * 10 Jan 2007
   5  */
   6
   7 #include <assert.h>
   8 #include <string.h>
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <math.h>
  12 #include <GL/gl.h>
  13 #include <GL/glut.h>
  14 #include <GL/glext.h>
  15 #include "extfuncs.h"
  16 #include "shaderutil.h"
  17
  18
  19 static char *FragProgFile = "CH06-brick.frag.txt";
  20 static char *VertProgFile = "CH06-brick.vert.txt";
  21
  22 /* program/shader objects */
  23 static GLuint fragShader;
  24 static GLuint vertShader;
  25 static GLuint program;
  26
  27 static struct uniform_info Uniforms[] = {
  28    /* vert */
  29    { "LightPosition",     3, GL_FLOAT, { 0.1, 0.1, 9.0, 0}, -1 },
  30    /* frag */
  31    { "BrickColor",        3, GL_FLOAT, { 0.8, 0.2, 0.2, 0 }, -1 },
  32    { "MortarColor",       3, GL_FLOAT, { 0.6, 0.6, 0.6, 0 }, -1 },
  33    { "BrickSize",         2, GL_FLOAT, { 1.0, 0.3, 0, 0 }, -1 },
  34    { "BrickPct",          2, GL_FLOAT, { 0.9, 0.8, 0, 0 }, -1 },
  35    END_OF_UNIFORMS
  36 };
  37
  38 static GLint win = 0;
  39
  40
  41 static GLfloat xRot = 0.0f, yRot = 0.0f, zRot = 0.0f;
  42
  43
  44
  45
  46 static void
  47 Redisplay(void)
  48 {
  49    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  50
  51    glPushMatrix();
  52    glRotatef(xRot, 1.0f, 0.0f, 0.0f);
  53    glRotatef(yRot, 0.0f, 1.0f, 0.0f);
  54    glRotatef(zRot, 0.0f, 0.0f, 1.0f);
  55
  56    glBegin(GL_POLYGON);
  57    glTexCoord2f(0, 0);   glVertex2f(-2, -2);
  58    glTexCoord2f(1, 0);   glVertex2f( 2, -2);
  59    glTexCoord2f(1, 1);   glVertex2f( 2,  2);
  60    glTexCoord2f(0, 1);   glVertex2f(-2,  2);
  61    glEnd();
  62
  63    glPopMatrix();
  64
  65    glutSwapBuffers();
  66 }
  67
  68
  69 static void
  70 Reshape(int width, int height)
  71 {
  72    glViewport(0, 0, width, height);
  73    glMatrixMode(GL_PROJECTION);
  74    glLoadIdentity();
  75    glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
  76    glMatrixMode(GL_MODELVIEW);
  77    glLoadIdentity();
  78    glTranslatef(0.0f, 0.0f, -15.0f);
  79 }
  80
  81
  82 static void
  83 CleanUp(void)
  84 {
  85    glDeleteShader_func(fragShader);
  86    glDeleteShader_func(vertShader);
  87    glDeleteProgram_func(program);
  88    glutDestroyWindow(win);
  89 }
  90
  91
  92 static void
  93 Key(unsigned char key, int x, int y)
  94 {
  95   (void) x;
  96   (void) y;
  97
  98    switch(key) {
  99    case 'z':
 100       zRot -= 1.0;
 101       break;
 102    case 'Z':
 103       zRot += 1.0;
 104       break;
 105    case 27:
 106       CleanUp();
 107       exit(0);
 108       break;
 109    }
 110    glutPostRedisplay();
 111 }
 112
 113
 114 static void
 115 SpecialKey(int key, int x, int y)
 116 {
 117    const GLfloat step = 3.0f;
 118
 119   (void) x;
 120   (void) y;
 121
 122    switch(key) {
 123    case GLUT_KEY_UP:
 124       xRot -= step;
 125       break;
 126    case GLUT_KEY_DOWN:
 127       xRot += step;
 128       break;
 129    case GLUT_KEY_LEFT:
 130       yRot -= step;
 131       break;
 132    case GLUT_KEY_RIGHT:
 133       yRot += step;
 134       break;
 135    }
 136    glutPostRedisplay();
 137 }
 138
 139
 140
 141 static void
 142 Init(void)
 143 {
 144    if (!ShadersSupported())
 145       exit(1);
 146
 147    GetExtensionFuncs();
 148
 149    vertShader = CompileShaderFile(GL_VERTEX_SHADER, VertProgFile);
 150    fragShader = CompileShaderFile(GL_FRAGMENT_SHADER, FragProgFile);
 151    program = LinkShaders(vertShader, fragShader);
 152
 153    glUseProgram_func(program);
 154
 155    InitUniforms(program, Uniforms);
 156
 157    assert(glGetError() == 0);
 158
 159    glClearColor(0.4f, 0.4f, 0.8f, 0.0f);
 160
 161    printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
 162
 163    assert(glIsProgram_func(program));
 164    assert(glIsShader_func(fragShader));
 165    assert(glIsShader_func(vertShader));
 166
 167    glColor3f(1, 0, 0);
 168 }
 169
 170
 171 static void
 172 ParseOptions(int argc, char *argv[])
 173 {
 174    int i;
 175    for (i = 1; i < argc; i++) {
 176       if (strcmp(argv[i], "-fs") == 0) {
 177          FragProgFile = argv[i+1];
 178       }
 179       else if (strcmp(argv[i], "-vs") == 0) {
 180          VertProgFile = argv[i+1];
 181       }
 182    }
 183 }
 184
 185
 186 int
 187 main(int argc, char *argv[])
 188 {
 189    glutInit(&argc, argv);
 190    glutInitWindowPosition( 0, 0);
 191    glutInitWindowSize(400, 400);
 192    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 193    win = glutCreateWindow(argv[0]);
 194    glutReshapeFunc(Reshape);
 195    glutKeyboardFunc(Key);
 196    glutSpecialFunc(SpecialKey);
 197    glutDisplayFunc(Redisplay);
 198    ParseOptions(argc, argv);
 199    Init();
 200    glutMainLoop();
 201    return 0;
 202 }
 203