140 lines
2.8 KiB
C
140 lines
2.8 KiB
C
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/* Exercise 1D textures
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*/
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#include <assert.h>
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "GL/glut.h"
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static GLuint Window = 0;
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static GLuint TexObj[2];
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static GLfloat Angle = 0.0f;
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static void draw( void )
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{
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glClear( GL_COLOR_BUFFER_BIT );
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glColor3f( 1.0, 1.0, 1.0 );
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/* draw first polygon */
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glPushMatrix();
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glTranslatef( -1.0, 0.0, 0.0 );
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glRotatef( Angle, 0.0, 0.0, 1.0 );
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glBindTexture( GL_TEXTURE_1D, TexObj[0] );
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glBegin( GL_POLYGON );
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glTexCoord1f( 0.0 ); glVertex2f( -1.0, -1.0 );
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glTexCoord1f( 1.0 ); glVertex2f( 1.0, -1.0 );
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glTexCoord1f( 1.0 ); glVertex2f( 1.0, 1.0 );
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glTexCoord1f( 0.0 ); glVertex2f( -1.0, 1.0 );
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glEnd();
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glPopMatrix();
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glutSwapBuffers();
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}
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static void idle( void )
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{
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Angle += 2.0;
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glutPostRedisplay();
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}
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/* change view Angle, exit upon ESC */
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static void key(unsigned char k, int x, int y)
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{
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(void) x;
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(void) y;
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switch (k) {
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case 27:
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exit(0);
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}
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}
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/* new window size or exposure */
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static void reshape( int width, int height )
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{
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glViewport(0, 0, (GLint)width, (GLint)height);
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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/* glOrtho( -3.0, 3.0, -3.0, 3.0, -10.0, 10.0 );*/
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glFrustum( -2.0, 2.0, -2.0, 2.0, 6.0, 20.0 );
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glMatrixMode(GL_MODELVIEW);
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glLoadIdentity();
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glTranslatef( 0.0, 0.0, -8.0 );
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}
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static void init( void )
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{
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GLubyte tex[256][3];
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GLint i;
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glDisable( GL_DITHER );
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/* Setup texturing */
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glEnable( GL_TEXTURE_1D );
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glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL );
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/* generate texture object IDs */
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glGenTextures( 2, TexObj );
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/* setup first texture object */
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glBindTexture( GL_TEXTURE_1D, TexObj[0] );
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for (i = 0; i < 256; i++) {
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GLfloat f;
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/* map 0..255 to -PI .. PI */
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f = ((i / 255.0) - .5) * (3.141592 * 2);
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f = sin(f);
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/* map -1..1 to 0..255 */
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tex[i][0] = (f+1.0)/2.0 * 255.0;
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tex[i][1] = 0;
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tex[i][2] = 0;
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}
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glTexImage1D( GL_TEXTURE_1D, 0, 3, 256, 0, GL_RGB, GL_UNSIGNED_BYTE, tex );
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glTexParameteri( GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
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glTexParameteri( GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
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glTexParameteri( GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_REPEAT );
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glTexParameteri( GL_TEXTURE_1D, GL_TEXTURE_WRAP_T, GL_REPEAT );
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}
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int main( int argc, char *argv[] )
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{
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glutInit(&argc, argv);
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glutInitWindowPosition(0, 0);
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glutInitWindowSize(300, 300);
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glutInitDisplayMode( GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE );
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Window = glutCreateWindow("Texture Objects");
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if (!Window) {
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exit(1);
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}
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init();
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glutReshapeFunc( reshape );
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glutKeyboardFunc( key );
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/* glutIdleFunc( idle ); */
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glutDisplayFunc( draw );
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glutMainLoop();
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return 0;
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}
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