src/demos/shadowtex.c

   1 /*
   2  * Shadow demo using the GL_ARB_depth_texture, GL_ARB_shadow and
   3  * GL_ARB_shadow_ambient extensions.
   4  *
   5  * Brian Paul
   6  * 19 Feb 2001
   7  *
   8  * Added GL_EXT_shadow_funcs support on 23 March 2002
   9  * Added GL_EXT_packed_depth_stencil support on 15 March 2006.
  10  * Added GL_EXT_framebuffer_object support on 27 March 2006.
  11  * Removed old SGIX extension support on 5 April 2006.
  12  * Added vertex / fragment program support on 7 June 2007 (Ian Romanick).
  13  *
  14  * Copyright (C) 1999-2006  Brian Paul   All Rights Reserved.
  15  *
  16  * Permission is hereby granted, free of charge, to any person obtaining a
  17  * copy of this software and associated documentation files (the "Software"),
  18  * to deal in the Software without restriction, including without limitation
  19  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  20  * and/or sell copies of the Software, and to permit persons to whom the
  21  * Software is furnished to do so, subject to the following conditions:
  22  *
  23  * The above copyright notice and this permission notice shall be included
  24  * in all copies or substantial portions of the Software.
  25  *
  26  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  27  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  28  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  29  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  30  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  31  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  32  */
  33
  34 #include <assert.h>
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38 #include <math.h>
  39 #include <GL/glew.h>
  40 #include "glut_wrap.h"
  41
  42 #define DEG_TO_RAD (3.14159 / 180.0)
  43
  44 static GLint WindowWidth = 450, WindowHeight = 300;
  45 static GLfloat Xrot = 15, Yrot = 0, Zrot = 0;
  46
  47 static GLfloat Red[4] = {1, 0, 0, 1};
  48 static GLfloat Green[4] = {0, 1, 0, 1};
  49 static GLfloat Blue[4] = {0, 0, 1, 1};
  50 static GLfloat Yellow[4] = {1, 1, 0, 1};
  51
  52 static GLfloat LightDist = 10;
  53 static GLfloat LightLatitude = 45.0;
  54 static GLfloat LightLongitude = 45.0;
  55 static GLfloat LightPos[4];
  56 static GLfloat SpotDir[3];
  57 static GLfloat SpotAngle = 40.0 * DEG_TO_RAD;
  58 static GLfloat ShadowNear = 4.0, ShadowFar = 24.0;
  59 static GLint ShadowTexWidth = 256, ShadowTexHeight = 256;
  60
  61 static GLboolean LinearFilter = GL_FALSE;
  62
  63 static GLfloat Bias = -0.06;
  64
  65 static GLboolean Anim = GL_TRUE;
  66
  67 static GLboolean NeedNewShadowMap = GL_FALSE;
  68 static GLuint ShadowTexture, GrayTexture;
  69 static GLuint ShadowFBO;
  70
  71 static GLfloat lightModelview[16];
  72 static GLfloat lightProjection[16];
  73
  74 static GLuint vert_prog;
  75 static GLuint frag_progs[3];
  76 static GLuint curr_frag = 0;
  77 static GLuint max_frag = 1;
  78
  79 #define NUM_FRAG_MODES 3
  80 static const char *FragProgNames[] = {
  81    "fixed-function",
  82    "program without \"OPTION ARB_fragment_program_shadow\"",
  83    "program with \"OPTION ARB_fragment_program_shadow\"",
  84 };
  85
  86 static GLboolean HaveShadow = GL_FALSE;
  87 static GLboolean HaveFBO = GL_FALSE;
  88 static GLboolean UseFBO = GL_FALSE;
  89 static GLboolean HaveVP = GL_FALSE;
  90 static GLboolean HaveFP = GL_FALSE;
  91 static GLboolean HaveFP_Shadow = GL_FALSE;
  92 static GLboolean UseVP = GL_FALSE;
  93 static GLboolean HavePackedDepthStencil = GL_FALSE;
  94 static GLboolean UsePackedDepthStencil = GL_FALSE;
  95 static GLboolean HaveEXTshadowFuncs = GL_FALSE;
  96 static GLboolean HaveShadowAmbient = GL_FALSE;
  97
  98 static GLint Operator = 0;
  99 static const GLenum OperatorFunc[8] = {
 100    GL_LEQUAL, GL_LESS, GL_GEQUAL, GL_GREATER,
 101    GL_EQUAL, GL_NOTEQUAL, GL_ALWAYS, GL_NEVER };
 102 static const char *OperatorName[8] = {
 103    "GL_LEQUAL", "GL_LESS", "GL_GEQUAL", "GL_GREATER",
 104    "GL_EQUAL", "GL_NOTEQUAL", "GL_ALWAYS", "GL_NEVER" };
 105
 106
 107 static GLuint DisplayMode;
 108 #define SHOW_SHADOWS        0
 109 #define SHOW_DEPTH_IMAGE    1
 110 #define SHOW_DEPTH_MAPPING  2
 111 #define SHOW_DISTANCE       3
 112
 113
 114
 115 #define MAT4_MUL(dest_vec, src_mat, src_vec) \
 116     "DP4        " dest_vec ".x, " src_mat "[0], " src_vec ";\n" \
 117     "DP4        " dest_vec ".y, " src_mat "[1], " src_vec ";\n" \
 118     "DP4        " dest_vec ".z, " src_mat "[2], " src_vec ";\n" \
 119     "DP4        " dest_vec ".w, " src_mat "[3], " src_vec ";\n"
 120
 121 #define MAT3_MUL(dest_vec, src_mat, src_vec) \
 122     "DP3        " dest_vec ".x, " src_mat "[0], " src_vec ";\n" \
 123     "DP3        " dest_vec ".y, " src_mat "[1], " src_vec ";\n" \
 124     "DP3        " dest_vec ".z, " src_mat "[2], " src_vec ";\n"
 125
 126 #define NORMALIZE(dest, src) \
 127     "DP3        " dest ".w, " src ", " src ";\n" \
 128     "RSQ        " dest ".w, " dest ".w;\n" \
 129     "MUL        " dest ", " src ", " dest ".w;\n"
 130
 131 /**
 132  * Vertex program for shadow mapping.
 133  */
 134 static const char vert_code[] =
 135     "!!ARBvp1.0\n"
 136     "ATTRIB iPos        = vertex.position;\n"
 137     "ATTRIB iNorm       = vertex.normal;\n"
 138
 139     "PARAM  mvinv[4]    = { state.matrix.modelview.invtrans };\n"
 140     "PARAM  mvp[4]      = { state.matrix.mvp };\n"
 141     "PARAM  mv[4]       = { state.matrix.modelview };\n"
 142     "PARAM  texmat[4]   = { state.matrix.texture[0] };\n"
 143     "PARAM  lightPos    = state.light[0].position;\n"
 144     "PARAM  ambientCol  = state.lightprod[0].ambient;\n"
 145     "PARAM  diffuseCol  = state.lightprod[0].diffuse;\n"
 146
 147     "TEMP   n, lightVec;\n"
 148     "ALIAS  V = lightVec;\n"
 149     "ALIAS  NdotL = n;\n"
 150
 151     "OUTPUT oPos = result.position;\n"
 152     "OUTPUT oColor = result.color;\n"
 153     "OUTPUT oTex = result.texcoord[0];\n"
 154
 155     /* Transform the vertex to clip coordinates. */
 156     MAT4_MUL("oPos", "mvp",    "iPos")
 157
 158     /* Transform the vertex to eye coordinates. */
 159     MAT4_MUL("V",    "mv",     "iPos")
 160
 161     /* Transform the vertex to projected light coordinates. */
 162     MAT4_MUL("oTex", "texmat", "iPos")
 163
 164     /* Transform the normal to eye coordinates. */
 165     MAT3_MUL("n",    "mvinv",  "iNorm")
 166
 167     /* Calculate the vector from the vertex to the light in eye
 168      * coordinates.
 169      */
 170     "SUB        lightVec, lightPos, V;\n"
 171     NORMALIZE("lightVec", "lightVec")
 172
 173     /* Compute diffuse lighting coefficient.
 174      */
 175     "DP3        NdotL.x, n, lightVec;\n"
 176     "MAX        NdotL.x, NdotL.x, {0.0};\n"
 177     "MIN        NdotL.x, NdotL.x, {1.0};\n"
 178
 179     /* Accumulate color contributions.
 180      */
 181     "MOV        oColor, diffuseCol;\n"
 182     "MAD        oColor.xyz, NdotL.x, diffuseCol, ambientCol;\n"
 183     "END\n"
 184     ;
 185
 186 static const char frag_code[] =
 187     "!!ARBfp1.0\n"
 188
 189     "TEMP   shadow, temp;\n"
 190
 191     "TXP        shadow, fragment.texcoord[0], texture[0], 2D;\n"
 192     "RCP        temp.x, fragment.texcoord[0].w;\n"
 193     "MUL        temp.x, temp.x, fragment.texcoord[0].z;\n"
 194     "SGE        shadow, shadow.x, temp.x;\n"
 195     "MUL        result.color.rgb, fragment.color, shadow.x;\n"
 196     "MOV        result.color.a, fragment.color;\n"
 197     "END\n"
 198     ;
 199
 200 static const char frag_shadow_code[] =
 201     "!!ARBfp1.0\n"
 202     "OPTION ARB_fragment_program_shadow;\n"
 203
 204     "TEMP   shadow;\n"
 205
 206     "TXP        shadow, fragment.texcoord[0], texture[0], SHADOW2D;\n"
 207     "MUL        result.color.rgb, fragment.color, shadow.x;\n"
 208     "MOV        result.color.a, fragment.color.a;\n"
 209     "END\n"
 210     ;
 211
 212 static void
 213 DrawScene(void)
 214 {
 215    GLfloat k = 6;
 216
 217    /* sphere */
 218    glPushMatrix();
 219    glTranslatef(1.6, 2.2, 2.7);
 220    glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, Green);
 221    glColor4fv(Green);
 222    glutSolidSphere(1.5, 15, 15);
 223    glPopMatrix();
 224    /* dodecahedron */
 225    glPushMatrix();
 226    glTranslatef(-2.0, 1.2, 2.1);
 227    glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, Red);
 228    glColor4fv(Red);
 229    glutSolidDodecahedron();
 230    glPopMatrix();
 231    /* icosahedron */
 232    glPushMatrix();
 233    glTranslatef(-0.6, 1.3, -0.5);
 234    glScalef(1.5, 1.5, 1.5);
 235    glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, Yellow);
 236    glColor4fv(Red);
 237    glutSolidIcosahedron();
 238    glPopMatrix();
 239    /* a plane */
 240    glPushMatrix();
 241    glTranslatef(0, -1.1, 0);
 242    glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, Blue);
 243    glColor4fv(Blue);
 244    glNormal3f(0, 1, 0);
 245    glBegin(GL_POLYGON);
 246    glVertex3f(-k, 0, -k);
 247    glVertex3f( k, 0, -k);
 248    glVertex3f( k, 0,  k);
 249    glVertex3f(-k, 0,  k);
 250    glEnd();
 251    glPopMatrix();
 252 }
 253
 254
 255 /**
 256  * Calculate modelview and project matrices for the light
 257  *
 258  * Stores the results in \c lightProjection (projection matrix) and
 259  * \c lightModelview (modelview matrix).
 260  */
 261 static void
 262 MakeShadowMatrix(const GLfloat lightPos[4], const GLfloat spotDir[3],
 263                  GLfloat spotAngle, GLfloat shadowNear, GLfloat shadowFar)
 264 {
 265    /* compute frustum to enclose spot light cone */
 266    const GLfloat d = shadowNear * tan(spotAngle);
 267
 268    glMatrixMode(GL_PROJECTION);
 269    glPushMatrix();
 270    glLoadIdentity();
 271    glFrustum(-d, d, -d, d, shadowNear, shadowFar);
 272    glGetFloatv(GL_PROJECTION_MATRIX, lightProjection);
 273    glPopMatrix();
 274
 275    glMatrixMode(GL_MODELVIEW);
 276    glPushMatrix();
 277    glLoadIdentity();
 278    gluLookAt(lightPos[0], lightPos[1], lightPos[2],
 279              lightPos[0] + spotDir[0],
 280              lightPos[1] + spotDir[1],
 281              lightPos[2] + spotDir[2],
 282              0.0, 1.0, 0.0);
 283    glGetFloatv(GL_MODELVIEW_MATRIX, lightModelview);
 284    glPopMatrix();
 285 }
 286
 287
 288 /**
 289  * Load \c GL_TEXTURE matrix with light's MVP matrix.
 290  */
 291 static void SetShadowTextureMatrix(void)
 292 {
 293    static const GLfloat biasMatrix[16] = {
 294       0.5, 0.0, 0.0, 0.0,
 295       0.0, 0.5, 0.0, 0.0,
 296       0.0, 0.0, 0.5, 0.0,
 297       0.5, 0.5, 0.5, 1.0,
 298    };
 299
 300    glMatrixMode(GL_TEXTURE);
 301    glLoadMatrixf(biasMatrix);
 302    glTranslatef(0.0, 0.0, Bias);
 303    glMultMatrixf(lightProjection);
 304    glMultMatrixf(lightModelview);
 305    glMatrixMode(GL_MODELVIEW);
 306 }
 307
 308
 309 static void
 310 EnableIdentityTexgen(void)
 311 {
 312    /* texgen so that texcoord = vertex coord */
 313    static GLfloat sPlane[4] = { 1, 0, 0, 0 };
 314    static GLfloat tPlane[4] = { 0, 1, 0, 0 };
 315    static GLfloat rPlane[4] = { 0, 0, 1, 0 };
 316    static GLfloat qPlane[4] = { 0, 0, 0, 1 };
 317
 318    glTexGenfv(GL_S, GL_EYE_PLANE, sPlane);
 319    glTexGenfv(GL_T, GL_EYE_PLANE, tPlane);
 320    glTexGenfv(GL_R, GL_EYE_PLANE, rPlane);
 321    glTexGenfv(GL_Q, GL_EYE_PLANE, qPlane);
 322    glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
 323    glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
 324    glTexGeni(GL_R, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
 325    glTexGeni(GL_Q, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
 326
 327    glEnable(GL_TEXTURE_GEN_S);
 328    glEnable(GL_TEXTURE_GEN_T);
 329    glEnable(GL_TEXTURE_GEN_R);
 330    glEnable(GL_TEXTURE_GEN_Q);
 331 }
 332
 333
 334 /*
 335  * Setup 1-D texgen so that the distance from the light source, between
 336  * the near and far planes maps to s=0 and s=1.  When we draw the scene,
 337  * the grayness will indicate the fragment's distance from the light
 338  * source.
 339  */
 340 static void
 341 EnableDistanceTexgen(const GLfloat lightPos[4], const GLfloat lightDir[3],
 342                      GLfloat lightNear, GLfloat lightFar)
 343 {
 344    GLfloat m, d;
 345    GLfloat sPlane[4];
 346    GLfloat nearPoint[3];
 347
 348    m = sqrt(lightDir[0] * lightDir[0] +
 349             lightDir[1] * lightDir[1] +
 350             lightDir[2] * lightDir[2]);
 351
 352    d = lightFar - lightNear;
 353
 354    /* nearPoint = point on light direction vector which intersects the
 355     * near plane of the light frustum.
 356     */
 357    nearPoint[0] = lightPos[0] + lightDir[0] / m * lightNear;
 358    nearPoint[1] = lightPos[1] + lightDir[1] / m * lightNear;
 359    nearPoint[2] = lightPos[2] + lightDir[2] / m * lightNear;
 360
 361    sPlane[0] = lightDir[0] / d / m;
 362    sPlane[1] = lightDir[1] / d / m;
 363    sPlane[2] = lightDir[2] / d / m;
 364    sPlane[3] = -(sPlane[0] * nearPoint[0]
 365                + sPlane[1] * nearPoint[1]
 366                + sPlane[2] * nearPoint[2]);
 367
 368    glTexGenfv(GL_S, GL_EYE_PLANE, sPlane);
 369    glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
 370    glEnable(GL_TEXTURE_GEN_S);
 371 }
 372
 373
 374 static void
 375 DisableTexgen(void)
 376 {
 377    glDisable(GL_TEXTURE_GEN_S);
 378    glDisable(GL_TEXTURE_GEN_T);
 379    glDisable(GL_TEXTURE_GEN_R);
 380    glDisable(GL_TEXTURE_GEN_Q);
 381 }
 382
 383
 384 static void
 385 ComputeLightPos(GLfloat dist, GLfloat latitude, GLfloat longitude,
 386                 GLfloat pos[4], GLfloat dir[3])
 387 {
 388
 389    pos[0] = dist * sin(longitude * DEG_TO_RAD);
 390    pos[1] = dist * sin(latitude * DEG_TO_RAD);
 391    pos[2] = dist * cos(latitude * DEG_TO_RAD) * cos(longitude * DEG_TO_RAD);
 392    pos[3] = 1;
 393    dir[0] = -pos[0];
 394    dir[1] = -pos[1];
 395    dir[2] = -pos[2];
 396 }
 397
 398
 399 /**
 400  * Render the shadow map / depth texture.
 401  * The result will be in the texture object named ShadowTexture.
 402  */
 403 static void
 404 RenderShadowMap(void)
 405 {
 406    GLenum depthFormat; /* GL_DEPTH_COMPONENT or GL_DEPTH_STENCIL_EXT */
 407    GLenum depthType; /* GL_UNSIGNED_INT_24_8_EXT or GL_UNSIGNED_INT */
 408
 409    if (WindowWidth >= 1024 && WindowHeight >= 1024) {
 410       ShadowTexWidth = ShadowTexHeight = 1024;
 411    }
 412    else if (WindowWidth >= 512 && WindowHeight >= 512) {
 413       ShadowTexWidth = ShadowTexHeight = 512;
 414    }
 415    else if (WindowWidth >= 256 && WindowHeight >= 256) {
 416       ShadowTexWidth = ShadowTexHeight = 256;
 417    }
 418    else {
 419       ShadowTexWidth = ShadowTexHeight = 128;
 420    }
 421    printf("Rendering %d x %d depth texture\n", ShadowTexWidth, ShadowTexHeight);
 422
 423    if (UsePackedDepthStencil) {
 424       depthFormat = GL_DEPTH_STENCIL_EXT;
 425       depthType = GL_UNSIGNED_INT_24_8_EXT;
 426    }
 427    else {
 428       depthFormat = GL_DEPTH_COMPONENT;
 429       depthType = GL_UNSIGNED_INT;
 430    }
 431
 432    glMatrixMode(GL_PROJECTION);
 433    glLoadMatrixf(lightProjection);
 434
 435    glMatrixMode(GL_MODELVIEW);
 436    glLoadMatrixf(lightModelview);
 437
 438    if (UseFBO) {
 439       GLenum fbo_status;
 440
 441       glTexImage2D(GL_TEXTURE_2D, 0, depthFormat,
 442                    ShadowTexWidth, ShadowTexHeight, 0,
 443                    depthFormat, depthType, NULL);
 444
 445       /* Set the filter mode so that the texture is texture-complete.
 446        * Otherwise it will cause the framebuffer to fail the framebuffer
 447        * completeness test.
 448        */
 449       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 450
 451       glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, ShadowFBO);
 452       glDrawBuffer(GL_NONE);
 453       glReadBuffer(GL_NONE);
 454
 455       fbo_status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
 456       if (fbo_status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 457          fprintf(stderr, "FBO not complete!  status = 0x%04x\n", fbo_status);
 458          assert(fbo_status == GL_FRAMEBUFFER_COMPLETE_EXT);
 459       }
 460    }
 461
 462    assert(!glIsEnabled(GL_TEXTURE_1D));
 463    assert(!glIsEnabled(GL_TEXTURE_2D));
 464
 465    glViewport(0, 0, ShadowTexWidth, ShadowTexHeight);
 466    glClear(GL_DEPTH_BUFFER_BIT);
 467    glEnable(GL_DEPTH_TEST);
 468    DrawScene();
 469
 470    if (UseFBO) {
 471       /* all done! */
 472       glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
 473    }
 474    else {
 475       /*
 476        * copy depth buffer into the texture map
 477        */
 478       if (DisplayMode == SHOW_DEPTH_MAPPING) {
 479          /* load depth image as gray-scale luminance texture */
 480          GLuint *depth = (GLuint *)
 481             malloc(ShadowTexWidth * ShadowTexHeight * sizeof(GLuint));
 482          assert(depth);
 483          glReadPixels(0, 0, ShadowTexWidth, ShadowTexHeight,
 484                       depthFormat, depthType, depth);
 485          glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE,
 486                       ShadowTexWidth, ShadowTexHeight, 0,
 487                       GL_LUMINANCE, GL_UNSIGNED_INT, depth);
 488          free(depth);
 489       }
 490       else {
 491          /* The normal shadow case - a real depth texture */
 492          glCopyTexImage2D(GL_TEXTURE_2D, 0, depthFormat,
 493                           0, 0, ShadowTexWidth, ShadowTexHeight, 0);
 494          if (UsePackedDepthStencil) {
 495             /* debug check */
 496             GLint intFormat;
 497             glGetTexLevelParameteriv(GL_TEXTURE_2D, 0,
 498                                      GL_TEXTURE_INTERNAL_FORMAT, &intFormat);
 499             assert(intFormat == GL_DEPTH_STENCIL_EXT);
 500          }
 501       }
 502    }
 503 }
 504
 505
 506 /**
 507  * Show the shadow map as a grayscale image.
 508  */
 509 static void
 510 ShowShadowMap(void)
 511 {
 512    glClear(GL_COLOR_BUFFER_BIT);
 513
 514    glMatrixMode(GL_TEXTURE);
 515    glLoadIdentity();
 516
 517    glMatrixMode(GL_PROJECTION);
 518    glLoadIdentity();
 519    glOrtho(0, WindowWidth, 0, WindowHeight, -1, 1);
 520
 521    glMatrixMode(GL_MODELVIEW);
 522    glLoadIdentity();
 523
 524    glDisable(GL_DEPTH_TEST);
 525    glDisable(GL_LIGHTING);
 526
 527    glEnable(GL_TEXTURE_2D);
 528
 529    DisableTexgen();
 530
 531    /* interpret texture's depth values as luminance values */
 532    if (HaveShadow) {
 533       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE_ARB, GL_NONE);
 534    }
 535
 536    glTexParameteri(GL_TEXTURE_2D, GL_DEPTH_TEXTURE_MODE_ARB, GL_LUMINANCE);
 537    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
 538
 539    glBegin(GL_POLYGON);
 540    glTexCoord2f(0, 0);  glVertex2f(0, 0);
 541    glTexCoord2f(1, 0);  glVertex2f(ShadowTexWidth, 0);
 542    glTexCoord2f(1, 1);  glVertex2f(ShadowTexWidth, ShadowTexHeight);
 543    glTexCoord2f(0, 1);  glVertex2f(0, ShadowTexHeight);
 544    glEnd();
 545
 546    glDisable(GL_TEXTURE_2D);
 547    glEnable(GL_DEPTH_TEST);
 548    glEnable(GL_LIGHTING);
 549 }
 550
 551
 552 /**
 553  * Redraw window image
 554  */
 555 static void
 556 Display(void)
 557 {
 558    GLenum error;
 559
 560    ComputeLightPos(LightDist, LightLatitude, LightLongitude,
 561                    LightPos, SpotDir);
 562
 563    if (NeedNewShadowMap) {
 564       MakeShadowMatrix(LightPos, SpotDir, SpotAngle, ShadowNear, ShadowFar);
 565       RenderShadowMap();
 566       NeedNewShadowMap = GL_FALSE;
 567    }
 568
 569    glViewport(0, 0, WindowWidth, WindowHeight);
 570    if (DisplayMode == SHOW_DEPTH_IMAGE) {
 571       ShowShadowMap();
 572    }
 573    else {
 574       /* prepare to draw scene from camera's view */
 575       const GLfloat ar = (GLfloat) WindowWidth / (GLfloat) WindowHeight;
 576
 577       glMatrixMode(GL_PROJECTION);
 578       glLoadIdentity();
 579       glFrustum(-ar, ar, -1.0, 1.0, 4.0, 50.0);
 580
 581       glMatrixMode(GL_MODELVIEW);
 582       glLoadIdentity();
 583       glTranslatef(0.0, 0.0, -22.0);
 584       glRotatef(Xrot, 1, 0, 0);
 585       glRotatef(Yrot, 0, 1, 0);
 586       glRotatef(Zrot, 0, 0, 1);
 587
 588       glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 589
 590       glLightfv(GL_LIGHT0, GL_POSITION, LightPos);
 591
 592       if (LinearFilter) {
 593          glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 594          glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 595       }
 596       else {
 597          glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 598          glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 599       }
 600
 601       if (DisplayMode == SHOW_DEPTH_MAPPING) {
 602          if (HaveShadow) {
 603             glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE_ARB, GL_NONE);
 604          }
 605          glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
 606          glEnable(GL_TEXTURE_2D);
 607
 608          SetShadowTextureMatrix();
 609          EnableIdentityTexgen();
 610       }
 611       else if (DisplayMode == SHOW_DISTANCE) {
 612          glMatrixMode(GL_TEXTURE);
 613          glLoadIdentity();
 614          glMatrixMode(GL_MODELVIEW);
 615          EnableDistanceTexgen(LightPos, SpotDir, ShadowNear+Bias, ShadowFar);
 616          glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
 617          glEnable(GL_TEXTURE_1D);
 618          assert(!glIsEnabled(GL_TEXTURE_2D));
 619       }
 620       else {
 621          assert(DisplayMode == SHOW_SHADOWS);
 622          if (HaveShadow) {
 623             glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE_ARB,
 624                             GL_COMPARE_R_TO_TEXTURE_ARB);
 625          }
 626
 627          if (curr_frag > 0) {
 628             glEnable(GL_FRAGMENT_PROGRAM_ARB);
 629          }
 630          else {
 631             glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
 632          }
 633          glEnable(GL_TEXTURE_2D);
 634
 635          SetShadowTextureMatrix();
 636
 637          if (UseVP) {
 638             glEnable(GL_VERTEX_PROGRAM_ARB);
 639          }
 640          else {
 641             glEnable(GL_LIGHTING);
 642             EnableIdentityTexgen();
 643          }
 644       }
 645
 646       DrawScene();
 647
 648       if (UseVP) {
 649          glDisable(GL_VERTEX_PROGRAM_ARB);
 650       }
 651       else {
 652          DisableTexgen();
 653          glDisable(GL_LIGHTING);
 654       }
 655
 656       if (curr_frag > 0) {
 657          glDisable(GL_FRAGMENT_PROGRAM_ARB);
 658       }
 659
 660       glDisable(GL_TEXTURE_1D);
 661       glDisable(GL_TEXTURE_2D);
 662    }
 663
 664    glutSwapBuffers();
 665
 666    error = glGetError();
 667    if (error) {
 668       printf("GL Error: %s\n", (char *) gluErrorString(error));
 669    }
 670 }
 671
 672
 673 static void
 674 Reshape(int width, int height)
 675 {
 676    WindowWidth = width;
 677    WindowHeight = height;
 678    NeedNewShadowMap = GL_TRUE;
 679 }
 680
 681
 682 static void
 683 Idle(void)
 684 {
 685    static double t0 = -1.;
 686    double dt, t = glutGet(GLUT_ELAPSED_TIME) / 1000.0;
 687    if (t0 < 0.0)
 688       t0 = t;
 689    dt = t - t0;
 690    t0 = t;
 691    Yrot += 75.0 * dt;
 692    /*LightLongitude -= 5.0;*/
 693    glutPostRedisplay();
 694 }
 695
 696
 697 static void
 698 Key(unsigned char key, int x, int y)
 699 {
 700    const GLfloat step = 3.0;
 701    (void) x;
 702    (void) y;
 703    switch (key) {
 704       case 'a':
 705          Anim = !Anim;
 706          if (Anim)
 707             glutIdleFunc(Idle);
 708          else
 709             glutIdleFunc(NULL);
 710          break;
 711       case 'b':
 712          Bias -= 0.01;
 713          printf("Bias %g\n", Bias);
 714          break;
 715       case 'B':
 716          Bias += 0.01;
 717          printf("Bias %g\n", Bias);
 718          break;
 719       case 'd':
 720          DisplayMode = SHOW_DISTANCE;
 721          break;
 722       case 'f':
 723          LinearFilter = !LinearFilter;
 724          printf("%s filtering\n", LinearFilter ? "Bilinear" : "Nearest");
 725          break;
 726       case 'i':
 727          DisplayMode = SHOW_DEPTH_IMAGE;
 728          break;
 729       case 'm':
 730          DisplayMode = SHOW_DEPTH_MAPPING;
 731          break;
 732       case 'M':
 733          curr_frag = (1 + curr_frag) % max_frag;
 734          if (!HaveShadow && (curr_frag == 0)) {
 735             curr_frag = 1;
 736          }
 737
 738          printf("Using fragment %s\n", FragProgNames[curr_frag]);
 739
 740          if (HaveFP) {
 741             glBindProgramARB(GL_FRAGMENT_PROGRAM_ARB, frag_progs[curr_frag]);
 742          }
 743          break;
 744       case 'n':
 745       case 's':
 746       case ' ':
 747          DisplayMode = SHOW_SHADOWS;
 748          break;
 749       case 'o':
 750          if (HaveEXTshadowFuncs) {
 751             Operator++;
 752             if (Operator >= 8)
 753                Operator = 0;
 754             printf("Operator: %s\n", OperatorName[Operator]);
 755             if (HaveShadow) {
 756                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_FUNC_ARB,
 757                                OperatorFunc[Operator]);
 758             }
 759          }
 760          break;
 761       case 'p':
 762          UsePackedDepthStencil = !UsePackedDepthStencil;
 763          if (UsePackedDepthStencil && !HavePackedDepthStencil) {
 764             printf("Sorry, GL_EXT_packed_depth_stencil not supported\n");
 765             UsePackedDepthStencil = GL_FALSE;
 766          }
 767          else {
 768             printf("Use GL_DEPTH_STENCIL_EXT: %d\n", UsePackedDepthStencil);
 769             /* Don't really need to regenerate shadow map texture, but do so
 770              * to exercise more code more often.
 771              */
 772             NeedNewShadowMap = GL_TRUE;
 773          }
 774          break;
 775       case 'v':
 776          UseVP = !UseVP && HaveVP;
 777          printf("Using vertex %s mode.\n",
 778                 UseVP ? "program" : "fixed-function");
 779          break;
 780       case 'z':
 781          Zrot -= step;
 782          break;
 783       case 'Z':
 784          Zrot += step;
 785          break;
 786       case 27:
 787          exit(0);
 788          break;
 789    }
 790    fflush(stdout);
 791    glutPostRedisplay();
 792 }
 793
 794
 795 static void
 796 SpecialKey(int key, int x, int y)
 797 {
 798    const GLfloat step = 3.0;
 799    const int mod = glutGetModifiers();
 800    (void) x;
 801    (void) y;
 802    switch (key) {
 803       case GLUT_KEY_UP:
 804          if (mod)
 805             LightLatitude += step;
 806          else
 807             Xrot += step;
 808          break;
 809       case GLUT_KEY_DOWN:
 810          if (mod)
 811             LightLatitude -= step;
 812          else
 813             Xrot -= step;
 814          break;
 815       case GLUT_KEY_LEFT:
 816          if (mod)
 817             LightLongitude += step;
 818          else
 819             Yrot += step;
 820          break;
 821       case GLUT_KEY_RIGHT:
 822          if (mod)
 823             LightLongitude -= step;
 824          else
 825             Yrot -= step;
 826          break;
 827    }
 828    if (mod)
 829       NeedNewShadowMap = GL_TRUE;
 830
 831    glutPostRedisplay();
 832 }
 833
 834
 835 /* A helper for finding errors in program strings */
 836 static int FindLine( const char *program, int position )
 837 {
 838    int i, line = 1;
 839    for (i = 0; i < position; i++) {
 840       if (program[i] == '\n')
 841          line++;
 842    }
 843    return line;
 844 }
 845
 846
 847 static GLuint
 848 compile_program(GLenum target, const char *code)
 849 {
 850    GLuint p;
 851    GLint errorPos;
 852
 853
 854    glGenProgramsARB(1, & p);
 855
 856    glBindProgramARB(target, p);
 857    glProgramStringARB(target, GL_PROGRAM_FORMAT_ASCII_ARB,
 858                       strlen(code), code);
 859    glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &errorPos);
 860    if (glGetError() != GL_NO_ERROR || errorPos != -1) {
 861       int l = FindLine(code, errorPos);
 862       printf("Fragment Program Error (pos=%d line=%d): %s\n", errorPos, l,
 863              (char *) glGetString(GL_PROGRAM_ERROR_STRING_ARB));
 864       exit(0);
 865    }
 866
 867    glBindProgramARB(target, 0);
 868    return p;
 869 }
 870
 871 static void
 872 Init(void)
 873 {
 874    static const GLfloat borderColor[4] = {1.0, 0.0, 0.0, 0.0};
 875
 876    if (!glutExtensionSupported("GL_ARB_depth_texture")) {
 877       printf("Sorry, this demo requires the GL_ARB_depth_texture extension\n");
 878       exit(1);
 879    }
 880
 881    HaveShadow = glutExtensionSupported("GL_ARB_shadow");
 882    HaveVP = glutExtensionSupported("GL_ARB_vertex_program");
 883    HaveFP = glutExtensionSupported("GL_ARB_fragment_program");
 884    HaveFP_Shadow = glutExtensionSupported("GL_ARB_fragment_program_shadow");
 885
 886    if (!HaveShadow && !HaveFP) {
 887       printf("Sorry, this demo requires either the GL_ARB_shadow extension "
 888              "or the GL_ARB_fragment_program extension\n");
 889       exit(1);
 890    }
 891
 892    printf("Using GL_ARB_depth_texture\n");
 893    if (HaveShadow) {
 894       printf("and GL_ARB_shadow\n");
 895    }
 896
 897    if (HaveFP) {
 898       printf("and GL_ARB_fragment_program\n");
 899    }
 900
 901    HaveShadowAmbient = glutExtensionSupported("GL_ARB_shadow_ambient");
 902    if (HaveShadowAmbient) {
 903       printf("and GL_ARB_shadow_ambient\n");
 904    }
 905
 906    HaveEXTshadowFuncs = glutExtensionSupported("GL_EXT_shadow_funcs");
 907
 908    HavePackedDepthStencil = glutExtensionSupported("GL_EXT_packed_depth_stencil");
 909    UsePackedDepthStencil = HavePackedDepthStencil;
 910
 911 #if defined(GL_EXT_framebuffer_object)
 912    HaveFBO = glutExtensionSupported("GL_EXT_framebuffer_object");
 913    UseFBO = HaveFBO;
 914    if (UseFBO) {
 915       printf("Using GL_EXT_framebuffer_object\n");
 916    }
 917 #endif
 918
 919    /*
 920     * Set up the 2D shadow map texture
 921     */
 922    glGenTextures(1, &ShadowTexture);
 923    glBindTexture(GL_TEXTURE_2D, ShadowTexture);
 924    glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, borderColor);
 925    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
 926    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
 927
 928    if (HaveShadow) {
 929       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE_ARB,
 930                       GL_COMPARE_R_TO_TEXTURE_ARB);
 931       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_FUNC_ARB, GL_LEQUAL);
 932    }
 933
 934    if (HaveShadowAmbient) {
 935       glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_FAIL_VALUE_ARB, 0.3);
 936    }
 937
 938 #if defined(GL_EXT_framebuffer_object)
 939    if (UseFBO) {
 940       glGenFramebuffersEXT(1, &ShadowFBO);
 941       glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, ShadowFBO);
 942       glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT,
 943                                    GL_COLOR_ATTACHMENT0_EXT,
 944                                    GL_RENDERBUFFER_EXT, 0);
 945       glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,
 946                                 GL_TEXTURE_2D, ShadowTexture, 0);
 947
 948       glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
 949    }
 950 #endif
 951
 952    /*
 953     * Setup 1-D grayscale texture image for SHOW_DISTANCE mode
 954     */
 955    glGenTextures(1, &GrayTexture);
 956    glBindTexture(GL_TEXTURE_1D, GrayTexture);
 957    glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_CLAMP);
 958    glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 959    glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 960    {
 961       GLuint i;
 962       GLubyte image[256];
 963       for (i = 0; i < 256; i++)
 964          image[i] = i;
 965       glTexImage1D(GL_TEXTURE_1D, 0, GL_LUMINANCE,
 966                    256, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, image);
 967    }
 968
 969    if (HaveVP) {
 970       vert_prog = compile_program(GL_VERTEX_PROGRAM_ARB, vert_code);
 971       glBindProgramARB(GL_VERTEX_PROGRAM_ARB, vert_prog);
 972    }
 973
 974    max_frag = 1;
 975    frag_progs[0] = 0;
 976
 977    if (HaveFP) {
 978       frag_progs[1] = compile_program(GL_FRAGMENT_PROGRAM_ARB, frag_code);
 979       max_frag = 2;
 980    }
 981
 982    if (HaveFP && HaveFP_Shadow) {
 983       frag_progs[2] = compile_program(GL_FRAGMENT_PROGRAM_ARB,
 984                                       frag_shadow_code);
 985       max_frag = 3;
 986    }
 987
 988    if (!HaveShadow) {
 989       curr_frag = 1;
 990       glBindProgramARB(GL_FRAGMENT_PROGRAM_ARB, frag_progs[curr_frag]);
 991    }
 992
 993    glEnable(GL_DEPTH_TEST);
 994    glEnable(GL_LIGHTING);
 995    glEnable(GL_LIGHT0);
 996 }
 997
 998
 999 static void
1000 PrintHelp(void)
1001 {
1002    printf("Keys:\n");
1003    printf("  a = toggle animation\n");
1004    printf("  i = show depth texture image\n");
1005    printf("  m = show depth texture mapping\n");
1006    printf("  d = show fragment distance from light source\n");
1007    printf("  n = show normal, shadowed image\n");
1008    printf("  f = toggle nearest/bilinear texture filtering\n");
1009    printf("  b/B = decrease/increase shadow map Z bias\n");
1010    printf("  p = toggle use of packed depth/stencil\n");
1011    printf("  M = cycle through fragment program modes\n");
1012    printf("  v = toggle vertex program modes\n");
1013    printf("  cursor keys = rotate scene\n");
1014    printf("  <shift> + cursor keys = rotate light source\n");
1015    if (HaveEXTshadowFuncs)
1016       printf("  o = cycle through comparison modes\n");
1017    fflush(stdout);
1018 }
1019
1020
1021 int
1022 main(int argc, char *argv[])
1023 {
1024    glutInitWindowSize(WindowWidth, WindowHeight);
1025    glutInit(&argc, argv);
1026    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH | GLUT_STENCIL);
1027    glutCreateWindow(argv[0]);
1028    glewInit();
1029    glutReshapeFunc(Reshape);
1030    glutKeyboardFunc(Key);
1031    glutSpecialFunc(SpecialKey);
1032    glutDisplayFunc(Display);
1033    if (Anim)
1034       glutIdleFunc(Idle);
1035    Init();
1036    PrintHelp();
1037    glutMainLoop();
1038    return 0;
1039 }