| /* |
| * GL_SGIS_pixel_texture demo |
| * |
| * Brian Paul |
| * 6 Apr 2000 |
| * |
| * Copyright (C) 2000 Brian Paul All Rights Reserved. |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a |
| * copy of this software and associated documentation files (the "Software"), |
| * to deal in the Software without restriction, including without limitation |
| * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
| * and/or sell copies of the Software, and to permit persons to whom the |
| * Software is furnished to do so, subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be included |
| * in all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS |
| * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
| * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN |
| * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
| * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
| */ |
| |
| |
| /* |
| * How this works: |
| * 1. We load the image into a 2D texture. |
| * 2. We generate a sequence of RGB images in which the R component |
| * is really the S texture coordinate and the G component is really |
| * the T texture coordinate. |
| * By warping the mapping from R to S and G to T we can get non-linear |
| * distortions. |
| * 3. Draw the warped image (a 2-D warping function) with pixel texgen |
| * enabled. |
| * 4. Loop over the warped images to animate. |
| * |
| * The pixel texgen extension can also be used to do color-space |
| * conversions. For example, we could convert YCR to RGB with a |
| * 3D texture map which takes YCR as the S,T,R texture coordinate and |
| * returns RGB texel values. |
| * |
| * You can use this extension in (at least) two ways: |
| * 1. glDrawPixels w/ color space conversion/warping |
| * 2. glDrawPixels to spatially warp another image in texture memory |
| * |
| * We're basically using glDrawPixels to draw a texture coordinate image. |
| */ |
| |
| |
| #include <math.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <GL/glut.h> |
| #include <GL/glext.h> |
| #include "../util/readtex.c" /* I know, this is a hack. */ |
| |
| #define TEXTURE_FILE "../images/girl.rgb" |
| |
| static int ImgWidth = 300, ImgHeight = 300; |
| #define FRAMES 20 |
| static GLubyte *ImgData[FRAMES]; |
| static GLint Frame = 0; |
| |
| static GLboolean TextureFlag = GL_TRUE; |
| |
| |
| static void Display( void ) |
| { |
| glClear( GL_COLOR_BUFFER_BIT ); |
| |
| if (TextureFlag) { |
| glEnable(GL_PIXEL_TEXTURE_SGIS); |
| glEnable(GL_TEXTURE_2D); |
| } |
| else { |
| glDisable(GL_PIXEL_TEXTURE_SGIS); |
| glDisable(GL_TEXTURE_2D); |
| } |
| |
| glColor3f(1, 1, 1); |
| glRasterPos2f(10, 10); |
| glDrawPixels(ImgWidth, ImgHeight, GL_RGB, GL_UNSIGNED_BYTE, ImgData[Frame]); |
| |
| glutSwapBuffers(); |
| } |
| |
| |
| static void Reshape( int width, int height ) |
| { |
| glViewport( 0, 0, width, height ); |
| glMatrixMode( GL_PROJECTION ); |
| glLoadIdentity(); |
| glOrtho(0, width, 0, height, -1, 1); |
| glMatrixMode( GL_MODELVIEW ); |
| glLoadIdentity(); |
| } |
| |
| |
| static void Key( unsigned char key, int x, int y ) |
| { |
| (void) x; |
| (void) y; |
| switch (key) { |
| case ' ': |
| TextureFlag = !TextureFlag; |
| break; |
| case 27: |
| exit(0); |
| break; |
| } |
| glutPostRedisplay(); |
| } |
| |
| |
| static void Idle(void) |
| { |
| Frame++; |
| if (Frame >= FRAMES) |
| Frame = 0; |
| glutPostRedisplay(); |
| } |
| |
| |
| static GLubyte warp(GLfloat s, int frame) |
| { |
| static const GLfloat PI = 3.14159265; |
| static int halfFrame = FRAMES / 2; |
| GLfloat y, weight, v; |
| if (frame >= halfFrame) |
| frame = halfFrame - (frame - halfFrame); |
| y = sin(s * PI); |
| weight = (float) frame / (FRAMES-1); |
| v = y * (0.8 * weight + 0.2); |
| return (GLint) (v * 255.0F); |
| } |
| |
| |
| static void InitImage(void) |
| { |
| int i, j, frame; |
| for (frame = 0; frame < FRAMES; frame++) { |
| ImgData[frame] = (GLubyte *) malloc(ImgWidth * ImgHeight * 3); |
| for (i = 0; i < ImgHeight; i++) { |
| for (j = 0; j < ImgWidth; j++) { |
| GLubyte *pixel = ImgData[frame] + (i * ImgWidth + j) * 3; |
| pixel[0] = warp((float) j / (ImgWidth - 0), frame); |
| pixel[1] = warp((float) i / (ImgHeight - 0), frame); |
| pixel[2] = 0.0; |
| } |
| } |
| } |
| } |
| |
| |
| static void Init( int argc, char *argv[] ) |
| { |
| const char *exten = (const char *) glGetString(GL_EXTENSIONS); |
| if (!strstr(exten, "GL_SGIS_pixel_texture")) { |
| printf("Sorry, GL_SGIS_pixel_texture not supported by this renderer.\n"); |
| exit(1); |
| } |
| |
| /* linear filtering looks nicer, but it's slower, since it's in software */ |
| #if 1 |
| 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_REPLACE); |
| |
| glPixelStorei(GL_UNPACK_ALIGNMENT, 1); |
| |
| if (!LoadRGBMipmaps(TEXTURE_FILE, GL_RGB)) { |
| printf("Error: couldn't load texture image\n"); |
| exit(1); |
| } |
| |
| glClearColor(0.3, 0.3, 0.4, 1.0); |
| |
| InitImage(); |
| |
| printf("Hit SPACE to toggle pixel texgen\n"); |
| } |
| |
| |
| int main( int argc, char *argv[] ) |
| { |
| glutInit( &argc, argv ); |
| glutInitWindowSize( 330, 330 ); |
| glutInitWindowPosition( 0, 0 ); |
| glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE ); |
| glutCreateWindow(argv[0] ); |
| |
| Init( argc, argv ); |
| |
| glutKeyboardFunc( Key ); |
| glutReshapeFunc( Reshape ); |
| glutDisplayFunc( Display ); |
| glutIdleFunc( Idle ); |
| |
| glutMainLoop(); |
| return 0; |
| } |