/* $Id: multiext.c,v 1.1 1998/06/10 02:51:27 brianp Exp $ */ /* * Multitexture demo USING NEW GL_EXT_multitexture EXTENSION * Brian Paul June 1998 This program is in the public domain. */ /* * $Log: multiext.c,v $ * Revision 1.1 1998/06/10 02:51:27 brianp * Initial revision * */ /* * Some information about the multitexture extension: There are two distinct elements to texture mapping: coordinate specification and sampling/application. This distinction must be understood in order to effectively use multitexturing. The multitexture extension supports multiple sets of texture coordinates and multiple texture environments (an environment is a texture image and its sampling and application parameters.) Typically, texture coordinate set 0 is used to sample texture image 0 and texture coordinate set 1 is used to sample texture image 1. But, it's also possible to use coordinate set 0 to sample both images (as seen later). The number of texture coordinate sets available is queried with glGetIntegerv(GL_MAX_TEXTURE_COORD_SETS_EXT, &n). The number of texture environments available is queried with glGetIntegerv(GL_MAX_TEXTURES_EXT, &n). Coordinate specification: The new glMultiTexCoord*EXT() functions take a target parameter which explictly controls which set of texture coordinates are being set. The normal glTexCoord() functions modify the GL_TEXTURE0_EXT (0th) set of texture coordinates, by default. The new glSelectTextureCoordSetEXT() function is used to change the texture coordinate set targeted by the glTexCoord() functions. For example, after calling glSelectTextureCoordSetEXT(GL_TEXTURE1_EXT) the glTexCoord*() functions will modify texture coordinate set 1 instead of 0. Texture sampling/application: The texture environment controls how textures are sampled (nearest, linear, etc) and applied (replace, modulate, blend, etc). glSelectTextureEXT() selects the current texture environment. Subsequent calls to glTexEnv*(), glTexParameter*(), glTexImage*D(), etc will address the texture environment which was specified by glSelectTextureEXT(). Of particular interest is the call glTexEnv*(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COORD_SET_EXT, t). This controls the texture coordinate source for the current texture environment. For example, if you have two texture environments and want both to use texture coordinate set 0 then you would do the following: glSelectTextureEXT(GL_TEXTURE0_EXT); glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COORD_SET_EXT, GL_TEXTURE0_EXT); glSelectTextureEXT(GL_TEXTURE1_EXT); glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COORD_SET_EXT, GL_TEXTURE0_EXT); Another example- if you have two texture environments and wanted to use separate texture coordinates for each environment then you would do the following: glSelectTextureEXT(GL_TEXTURE0_EXT); glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COORD_SET_EXT, GL_TEXTURE0_EXT); glSelectTextureEXT(GL_TEXTURE1_EXT); glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COORD_SET_EXT, GL_TEXTURE1_EXT); Coordinate transformation and automatic generation: Multitexturing also replicates texture coordinate transformation state. That is, there will be multiple texture coordinate matrices and texture matrix stacks. Texture matrix 0 will transform texture coordiante set 0, texture matrix 1 will transform texture coordiante set 1, etc. Similarly, automatic texture coordinate generation can be independantly specified for each texture coordinate set. The new glSelectTextureTransformEXT() function controls which texture matrix or texgen state is the current one. For example, after calling glSelectTextureTransformEXT(GL_TEXTUREn_EXT) and glMatrixMode(GL_TEXTURE) the nth texture matrix will be effected by subsequent glLoadMatrix(), glMultMatrix(), glTranslate(), etc calls. The demonstration program below does exactly this. */ #include #include #include #include #include #include "../util/readtex.c" /* I know, this is a hack. */ #define TEX0 1 #define TEX1 2 #define TEXBOTH 3 #define ANIMATE 10 #define QUIT 100 static GLboolean Animate = GL_TRUE; static GLfloat Drift = 0.0; static GLfloat Xrot = 20.0, Yrot = 30.0, Zrot = 0.0; static GLfloat DXrot = 1.0, DYrot = 2.5; static void Idle( void ) { if (Animate) { Drift += 0.05; /* Transformation of texture coordinate set 0 */ #ifdef GL_EXT_multitexture glSelectTextureTransformEXT(GL_TEXTURE0_EXT); #endif glMatrixMode(GL_TEXTURE); glLoadIdentity(); glTranslatef(Drift, 0.0, 0.0); /* Transformation of texture coordinate set 1 */ #ifdef GL_EXT_multitexture glSelectTextureTransformEXT(GL_TEXTURE1_EXT); #endif glMatrixMode(GL_TEXTURE); glLoadIdentity(); glTranslatef(0.0, Drift, 0.0); glMatrixMode(GL_MODELVIEW); glutPostRedisplay(); } } static void DrawObject(void) { glBegin(GL_QUADS); #ifdef GL_EXT_multitexture glMultiTexCoord2fEXT(GL_TEXTURE0_EXT, 0.0, 0.0); glMultiTexCoord2fEXT(GL_TEXTURE1_EXT, 0.0, 0.0); glVertex2f(-1.0, -1.0); glMultiTexCoord2fEXT(GL_TEXTURE0_EXT, 2.0, 0.0); glMultiTexCoord2fEXT(GL_TEXTURE1_EXT, 1.0, 0.0); glVertex2f(1.0, -1.0); glMultiTexCoord2fEXT(GL_TEXTURE0_EXT, 2.0, 2.0); glMultiTexCoord2fEXT(GL_TEXTURE1_EXT, 1.0, 1.0); glVertex2f(1.0, 1.0); glMultiTexCoord2fEXT(GL_TEXTURE0_EXT, 0.0, 2.0); glMultiTexCoord2fEXT(GL_TEXTURE1_EXT, 0.0, 1.0); glVertex2f(-1.0, 1.0); #else glTexCoord2f(0.0, 0.0); glVertex2f(-1.0, -1.0); glTexCoord2f(1.0, 0.0); glVertex2f(1.0, -1.0); glTexCoord2f(1.0, 1.0); glVertex2f(1.0, 1.0); glTexCoord2f(0.0, 1.0); glVertex2f(-1.0, 1.0); #endif glEnd(); } static void Display( void ) { glClear( GL_COLOR_BUFFER_BIT ); glPushMatrix(); glRotatef(Xrot, 1.0, 0.0, 0.0); glRotatef(Yrot, 0.0, 1.0, 0.0); glRotatef(Zrot, 0.0, 0.0, 1.0); glScalef(5.0, 5.0, 5.0); DrawObject(); glPopMatrix(); glutSwapBuffers(); } static void Reshape( int width, int height ) { glViewport( 0, 0, width, height ); glMatrixMode( GL_PROJECTION ); glLoadIdentity(); glFrustum( -1.0, 1.0, -1.0, 1.0, 10.0, 100.0 ); /*glOrtho( -6.0, 6.0, -6.0, 6.0, 10.0, 100.0 );*/ glMatrixMode( GL_MODELVIEW ); glLoadIdentity(); glTranslatef( 0.0, 0.0, -70.0 ); } static void ModeMenu(int entry) { GLboolean enable0 = GL_FALSE, enable1 = GL_FALSE; if (entry==TEX0) { enable0 = GL_TRUE; } else if (entry==TEX1) { enable1 = GL_TRUE; } else if (entry==TEXBOTH) { enable0 = GL_TRUE; enable1 = GL_TRUE; } else if (entry==ANIMATE) { Animate = !Animate; } else if (entry==QUIT) { exit(0); } if (entry != ANIMATE) { #ifdef GL_EXT_multitexture glSelectTextureEXT(GL_TEXTURE0_EXT); #endif if (enable0) { glEnable(GL_TEXTURE_2D); } else glDisable(GL_TEXTURE_2D); #ifdef GL_EXT_multitexture glSelectTextureEXT(GL_TEXTURE1_EXT); #endif if (enable1) { glEnable(GL_TEXTURE_2D); } else glDisable(GL_TEXTURE_2D); } glutPostRedisplay(); } static void Key( unsigned char key, int x, int y ) { switch (key) { case 27: exit(0); break; } glutPostRedisplay(); } static void SpecialKey( int key, int x, int y ) { float step = 3.0; switch (key) { case GLUT_KEY_UP: Xrot += step; break; case GLUT_KEY_DOWN: Xrot -= step; break; case GLUT_KEY_LEFT: Yrot += step; break; case GLUT_KEY_RIGHT: Yrot -= step; break; } glutPostRedisplay(); } static void Init( void ) { const char *exten = (const char *) glGetString(GL_EXTENSIONS); if (!strstr(exten, "GL_EXT_multitexture")) { printf("Sorry, GL_EXT_multitexture not supported by this renderer.\n"); exit(1); } /* setup textur env 0 */ #ifdef GL_EXT_multitexture glSelectTextureEXT(GL_TEXTURE0_EXT); glSelectTextureCoordSetEXT(GL_TEXTURE0_EXT); #endif #ifdef LINEAR_FILTER /* linear filtering looks much nicer but is much slower for Mesa */ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); #else glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); #endif glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); glPixelStorei(GL_UNPACK_ALIGNMENT, 1); if (!LoadRGBMipmaps("girl.rgb", GL_RGB)) { printf("Error: couldn't load texture image\n"); exit(1); } /* setup textur env 1 */ #ifdef GL_EXT_multitexture glSelectTextureEXT(GL_TEXTURE1_EXT); glSelectTextureCoordSetEXT(GL_TEXTURE1_EXT); #endif #ifdef LINEAR_FILTER /* linear filtering looks much nicer but is much slower for Mesa */ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); #else glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); #endif glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); if (!LoadRGBMipmaps("reflect.rgb", GL_RGB)) { printf("Error: couldn't load texture image\n"); exit(1); } glShadeModel(GL_FLAT); glClearColor(0.3, 0.3, 0.4, 1.0); ModeMenu(TEXBOTH); } int main( int argc, char *argv[] ) { glutInit( &argc, argv ); glutInitWindowSize( 300, 300 ); glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE ); glutCreateWindow(argv[0] ); Init(); glutReshapeFunc( Reshape ); glutKeyboardFunc( Key ); glutSpecialFunc( SpecialKey ); glutDisplayFunc( Display ); glutIdleFunc( Idle ); glutCreateMenu(ModeMenu); glutAddMenuEntry("Texture 0", TEX0); glutAddMenuEntry("Texture 1", TEX1); glutAddMenuEntry("Multi-texture", TEXBOTH); glutAddMenuEntry("Toggle Animation", ANIMATE); glutAddMenuEntry("Quit", QUIT); glutAttachMenu(GLUT_RIGHT_BUTTON); glutMainLoop(); return 0; }