fog_coord demo

1 files changed, 414 insertions, 0 deletions

diff --git a/progs/demos/fogcoord.c b/progs/demos/fogcoord.c
new file mode 100644
index 0000000000..e44d1178c0
--- /dev/null
+++ b/progs/demos/fogcoord.c
@@ -0,0 +1,414 @@
+/*
+ * EXT_fog_coord.
+ *
+ * Based on glutskel.c by Brian Paul
+ * and NeHe's Volumetric fog tutorial!
+ *
+ * Daniel Borca
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <GL/glut.h>
+
+#include "readtex.c" /* the compulsory hack  */
+
+#define TEXTURE_FILE "../images/bw.rgb"
+
+#define ARRAYS 0     /* use glDrawElements   */
+
+#define VERBOSE 1    /* tell me what happens */
+
+#define DEPTH 15.0f
+#define EPS   1e-6f
+
+typedef void (GLAPIENTRYP GLFOGCOORDFEXTPROC) (GLfloat f);
+typedef void (GLAPIENTRYP GLFOGCOORDPOINTEREXTPROC) (GLenum, GLsizei, const GLvoid *);
+
+static GLFOGCOORDFEXTPROC glFogCoordf_ext;
+static GLFOGCOORDPOINTEREXTPROC glFogCoordPointer_ext;
+static GLboolean have_fog_coord;
+
+static GLfloat camz;
+static GLuint texture[1];
+
+static GLint fogMode;
+static GLboolean fogCoord;
+static GLfloat fogDensity = 0.75;
+static GLfloat fogStart = 0.0, fogEnd = 1.0;
+static GLfloat fogColor[4] = {0.6f, 0.3f, 0.0f, 1.0f};
+
+
+void APIENTRY glFogCoordf_nop (GLfloat f)
+{
+ (void)f;
+}
+
+
+static int BuildTexture (const char *filename, GLuint texid[])
+{
+ GLubyte *tex_data;
+ GLenum tex_format;
+ GLint tex_width, tex_height;
+
+ tex_data = LoadRGBImage(filename, &tex_width, &tex_height, &tex_format);
+ if (tex_data == NULL) {
+    return -1;
+ }
+
+ {
+  GLint tex_max;
+  glGetIntegerv(GL_MAX_TEXTURE_SIZE, &tex_max);
+  if ((tex_width > tex_max) || (tex_height > tex_max)) {
+     return -1;
+  }
+ }
+
+ glGenTextures(1, texid);
+
+ glBindTexture(GL_TEXTURE_2D, texid[0]);
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+ glTexImage2D(GL_TEXTURE_2D, 0, tex_format, tex_width, tex_height, 0, tex_format, GL_UNSIGNED_BYTE, tex_data);
+
+ return 0;
+}
+
+
+static int SetFogMode (GLint fogMode)
+{
+ fogMode &= 3;
+ switch (fogMode) {
+        case 0:
+             glDisable(GL_FOG);
+#if VERBOSE
+             printf("fog(disable)\n");
+#endif
+             break;
+        case 1:
+             glEnable(GL_FOG);
+             glFogi(GL_FOG_MODE, GL_LINEAR);
+             glFogf(GL_FOG_START, fogStart);
+             glFogf(GL_FOG_END, fogEnd);
+#if VERBOSE
+             printf("fog(GL_LINEAR, %.2f, %.2f)\n", fogStart, fogEnd);
+#endif
+             break;
+        case 2:
+             glEnable(GL_FOG);
+             glFogi(GL_FOG_MODE, GL_EXP);
+             glFogf(GL_FOG_DENSITY, fogDensity);
+#if VERBOSE
+             printf("fog(GL_EXP, %.2f)\n", fogDensity);
+#endif
+             break;
+        case 3:
+             glEnable(GL_FOG);
+             glFogi(GL_FOG_MODE, GL_EXP2);
+             glFogf(GL_FOG_DENSITY, fogDensity);
+#if VERBOSE
+             printf("fog(GL_EXP2, %.2f)\n", fogDensity);
+#endif
+             break;
+ }
+ return fogMode;
+}
+
+
+static GLboolean SetFogCoord (GLboolean fogCoord)
+{
+ glFogCoordf_ext = glFogCoordf_nop;
+
+ if (!have_fog_coord) {
+#if VERBOSE
+    printf("fog(GL_FRAGMENT_DEPTH_EXT)%s\n", fogCoord ? " EXT_fog_coord not available!" : "");
+#endif
+    return GL_FALSE;
+ }
+
+ if (fogCoord) {
+    glFogCoordf_ext = (GLFOGCOORDFEXTPROC)glutGetProcAddress("glFogCoordfEXT");
+    glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FOG_COORDINATE_EXT);
+#if VERBOSE
+    printf("fog(GL_FOG_COORDINATE_EXT)\n");
+#endif
+ } else {
+    glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FRAGMENT_DEPTH_EXT);
+#if VERBOSE
+    printf("fog(GL_FRAGMENT_DEPTH_EXT)\n");
+#endif
+ }
+ return fogCoord;
+}
+
+
+#if ARRAYS
+/* could reuse vertices */
+static GLuint vertex_index[] = {
+   /* Back */
+   0, 1, 2, 3,
+
+   /* Floor */
+   4, 5, 6, 7,
+
+   /* Roof */
+   8, 9, 10, 11,
+
+   /* Right */
+   12, 13, 14, 15,
+
+   /* Left */
+   16, 17, 18, 19
+};
+
+static GLfloat vertex_pointer[][3] = {
+   /* Back */
+   {-2.5f,-2.5f,-DEPTH}, { 2.5f,-2.5f,-DEPTH}, { 2.5f, 2.5f,-DEPTH}, {-2.5f, 2.5f,-DEPTH},
+
+   /* Floor */
+   {-2.5f,-2.5f,-DEPTH}, { 2.5f,-2.5f,-DEPTH}, { 2.5f,-2.5f, DEPTH}, {-2.5f,-2.5f, DEPTH},
+
+   /* Roof */
+   {-2.5f, 2.5f,-DEPTH}, { 2.5f, 2.5f,-DEPTH}, { 2.5f, 2.5f, DEPTH}, {-2.5f, 2.5f, DEPTH},
+
+   /* Right */
+   { 2.5f,-2.5f, DEPTH}, { 2.5f, 2.5f, DEPTH}, { 2.5f, 2.5f,-DEPTH}, { 2.5f,-2.5f,-DEPTH},
+
+   /* Left */
+   {-2.5f,-2.5f, DEPTH}, {-2.5f, 2.5f, DEPTH}, {-2.5f, 2.5f,-DEPTH}, {-2.5f,-2.5f,-DEPTH}
+};
+
+static GLfloat texcoord_pointer[][2] = {
+   /* Back */
+   {0.0f, 0.0f}, {1.0f, 0.0f}, {1.0f, 1.0f}, {0.0f, 1.0f},
+
+   /* Floor */
+   {0.0f, 0.0f}, {1.0f, 0.0f}, {1.0f, 1.0f}, {0.0f, 1.0f},
+
+   /* Roof */
+   {0.0f, 0.0f}, {1.0f, 0.0f}, {1.0f, 1.0f}, {0.0f, 1.0f},
+
+   /* Right */
+   {0.0f, 0.0f}, {0.0f, 1.0f}, {1.0f, 1.0f}, {1.0f, 0.0f},
+
+   /* Left */
+   {0.0f, 0.0f}, {0.0f, 1.0f}, {1.0f, 1.0f}, {1.0f, 0.0f}
+};
+
+static GLfloat fogcoord_pointer[][1] = {
+   /* Back */
+   {1.0f}, {1.0f}, {1.0f}, {1.0f},
+
+   /* Floor */
+   {1.0f}, {1.0f}, {0.0f}, {0.0f},
+
+   /* Roof */
+   {1.0f}, {1.0f}, {0.0f}, {0.0f},
+
+   /* Right */
+   {0.0f}, {0.0f}, {1.0f}, {1.0f},
+
+   /* Left */
+   {0.0f}, {0.0f}, {1.0f}, {1.0f}
+};
+#endif
+
+
+static void Display( void )
+{
+   glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+   glLoadIdentity ();
+   
+   glTranslatef(0.0f, 0.0f, camz);
+
+#if ARRAYS
+   glDrawElements(GL_QUADS, sizeof(vertex_index) / sizeof(vertex_index[0]), GL_UNSIGNED_INT, vertex_index);
+#else
+   /* Back */
+   glBegin(GL_QUADS);
+   glFogCoordf_ext(1.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(-2.5f,-2.5f,-DEPTH);
+   glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 2.5f,-2.5f,-DEPTH);
+   glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 2.5f, 2.5f,-DEPTH);
+   glFogCoordf_ext(1.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-2.5f, 2.5f,-DEPTH);
+   glEnd();
+
+   /* Floor */
+   glBegin(GL_QUADS);
+   glFogCoordf_ext(1.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(-2.5f,-2.5f,-DEPTH);
+   glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 2.5f,-2.5f,-DEPTH);
+   glFogCoordf_ext(0.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 2.5f,-2.5f, DEPTH);
+   glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-2.5f,-2.5f, DEPTH);
+   glEnd();
+
+   /* Roof */
+   glBegin(GL_QUADS);
+   glFogCoordf_ext(1.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(-2.5f, 2.5f,-DEPTH);
+   glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 2.5f, 2.5f,-DEPTH);
+   glFogCoordf_ext(0.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 2.5f, 2.5f, DEPTH);
+   glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-2.5f, 2.5f, DEPTH);
+   glEnd();
+
+   /* Right */
+   glBegin(GL_QUADS);
+   glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f( 2.5f,-2.5f, DEPTH);
+   glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f( 2.5f, 2.5f, DEPTH);
+   glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 2.5f, 2.5f,-DEPTH);
+   glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 2.5f,-2.5f,-DEPTH);
+   glEnd();
+
+   /* Left */
+   glBegin(GL_QUADS);
+   glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(-2.5f,-2.5f, DEPTH);
+   glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-2.5f, 2.5f, DEPTH);
+   glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f(-2.5f, 2.5f,-DEPTH);
+   glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f(-2.5f,-2.5f,-DEPTH);
+   glEnd();
+#endif
+
+   glutSwapBuffers();
+}
+
+
+static void Reshape( int width, int height )
+{
+   glViewport(0, 0, width, height);
+   glMatrixMode(GL_PROJECTION);
+   glLoadIdentity();
+   gluPerspective(45.0f, (GLfloat)(width)/(GLfloat)(height), 0.1f, 100.0f);
+   glMatrixMode(GL_MODELVIEW);
+   glLoadIdentity();
+}
+
+
+static void Key( unsigned char key, int x, int y )
+{
+   (void) x;
+   (void) y;
+   switch (key) {
+      case 'f':
+         fogMode = SetFogMode(fogMode + 1);
+         break;
+      case '+':
+         if (fogDensity < 1.0 - EPS) {
+            fogDensity += 0.05;
+         }
+         SetFogMode(fogMode);
+         break;
+      case '-':
+         if (fogDensity > EPS) {
+            fogDensity -= 0.05;
+         }
+         SetFogMode(fogMode);
+         break;
+      case 's':
+         if (fogStart > EPS) {
+            fogStart -= 0.1;
+         }
+         SetFogMode(fogMode);
+         break;
+      case 'S':
+         if (fogStart < fogEnd - EPS) {
+            fogStart += 0.1;
+         }
+         SetFogMode(fogMode);
+         break;
+      case 'e':
+         if (fogEnd > fogStart + EPS) {
+            fogEnd -= 0.1;
+         }
+         SetFogMode(fogMode);
+         break;
+      case 'E':
+         if (fogEnd < 1.0 - EPS) {
+            fogEnd += 0.1;
+         }
+         SetFogMode(fogMode);
+         break;
+      case 'c':
+         fogCoord = SetFogCoord(fogCoord ^ GL_TRUE);
+         break;
+      case 27:
+         exit(0);
+         break;
+   }
+   glutPostRedisplay();
+}
+
+
+static void SpecialKey( int key, int x, int y )
+{
+   (void) x;
+   (void) y;
+   switch (key) {
+      case GLUT_KEY_UP:
+         if (camz < (DEPTH - 1.0)) {
+            camz += 1.0f;
+         }
+         break;
+      case GLUT_KEY_DOWN:
+         if (camz > -19.0) {
+            camz -= 1.0f;
+         }
+         break;
+   }
+   glutPostRedisplay();
+}
+
+
+static void Init( void )
+{
+   have_fog_coord = glutExtensionSupported("GL_EXT_fog_coord");
+
+   if (BuildTexture(TEXTURE_FILE, texture) == -1) {
+      exit(1);
+   }
+
+   glEnable(GL_TEXTURE_2D);
+   glClearColor(0.0f, 0.0f, 0.0f, 0.5f);
+   glClearDepth(1.0f);
+   glDepthFunc(GL_LEQUAL);
+   glEnable(GL_DEPTH_TEST);
+   glShadeModel(GL_SMOOTH);
+   glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
+
+   glFogfv(GL_FOG_COLOR, fogColor);
+   glHint(GL_FOG_HINT, GL_NICEST);
+   fogCoord = SetFogCoord(GL_TRUE); /* try to enable fog_coord */
+   fogMode = SetFogMode(2);         /* GL_EXP */
+
+   camz = -19.0f;
+
+#if ARRAYS
+   glEnableClientState(GL_VERTEX_ARRAY);
+   glVertexPointer(3, GL_FLOAT, 0, vertex_pointer);
+
+   glEnableClientState(GL_TEXTURE_COORD_ARRAY);
+   glTexCoordPointer(2, GL_FLOAT, 0, texcoord_pointer);
+
+   if (have_fog_coord) {
+      glFogCoordPointer_ext = (GLFOGCOORDPOINTEREXTPROC)glutGetProcAddress("glFogCoordPointerEXT");
+      glEnableClientState(GL_FOG_COORDINATE_ARRAY_EXT);
+      glFogCoordPointer_ext(GL_FLOAT, 0, fogcoord_pointer);
+   }
+#endif
+}
+
+
+int main( int argc, char *argv[] )
+{
+   glutInit( &argc, argv );
+   glutInitWindowPosition( 0, 0 );
+   glutInitWindowSize( 640, 480 );
+   glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH );
+   glutCreateWindow(argv[0]);
+   glutReshapeFunc( Reshape );
+   glutKeyboardFunc( Key );
+   glutSpecialFunc( SpecialKey );
+   glutDisplayFunc( Display );
+   Init();
+   glutMainLoop();
+   return 0;
+}