Changes between Version 17 and Version 18 of tutorial


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Timestamp:
Jun 28, 2013, 11:18:52 AM (6 years ago)
Author:
leon
Comment:

teapot

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  • tutorial

    v17 v18  
    325325  What happens if we don't enable temperature vertex array? Confer [attachment:temperature.c] attached if having troubles.
    326326 3. Add additional custom vertex array for the pressure. Change the temperature array to have values in Celsius for water boiling range [0-100]°C. Pressure should be in the range of [0-1] MPa. Scaling to color range [0-1] should be done in shaders. Toggle between them with the keyboard event by using the keys `'p'` and `'t`' that {{{glEnableVertexAttribArray()}}} and {{{glDisableVertexAttribArray()}}} corresponding vertex attribute arrays.
     327
     328
     329== Interactivity ==
     330[[Image(teapot.png,right)]]
     331
     332Assemble the following Utah teapot model and attached virtual [attachment:trackball.h] and [attachment:trackball.c] sources from SGI. We use
     333{{{
     334#!c
     335#include <stdio.h>
     336#include <stdlib.h>
     337#include <string.h>
     338
     339#include <GL/glew.h>
     340#include <GL/glut.h>
     341#include "trackball.h"
     342
     343GLuint p; // program needs to be global!
     344float lpos[4] = {1, 0.5, 1, 0};
     345GLfloat m[4][4]; // modelview rotation matrix
     346float last[4], cur[4]; // rotation tracking quaternions
     347int width, height, beginx, beginy;
     348float p1x, p1y, p2x, p2y;
     349
     350void display(void) {
     351  GLuint location = glGetUniformLocation(p, "RotationMatrix");
     352  build_rotmatrix(m, cur); 
     353  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
     354  glLightfv(GL_LIGHT0, GL_POSITION, lpos);
     355  if( location >= 0 )
     356    glUniformMatrix4fv(location, 1, GL_FALSE, &m[0][0]);
     357  glutSolidTeapot(0.6);
     358  glutSwapBuffers();
     359}
     360
     361
     362void processNormalKeys(unsigned char key, int x, int y) {
     363        if (key == 27)
     364                exit(0);
     365}
     366
     367void mouse(int button,int state, int x, int y)   
     368{
     369  beginx = x;
     370  beginy = y;
     371}
     372
     373void motion(int x,int y)   
     374{
     375  p1x = (2.0*beginx - width)/width;
     376  p1y = (height - 2.0*beginy)/height;
     377  p2x = (2.0 * x - width) / width;
     378  p2y = (height - 2.0 * y) / height;
     379  trackball(last, p1x, p1y, p2x, p2y);   
     380  add_quats(last, cur, cur);   
     381  beginx = x;
     382  beginy = y;
     383  glutPostRedisplay();   
     384}
     385
     386void reshape (int w, int h)
     387{
     388  double l = 1;
     389  width=w;  height=h;
     390  glViewport (0, 0, w, h);
     391  glMatrixMode (GL_PROJECTION);
     392  glLoadIdentity();
     393  glOrtho(-l, l, -l, l, -l, l);
     394  glMatrixMode(GL_MODELVIEW);
     395  glLoadIdentity();
     396}
     397
     398static const GLchar * vertex_shader[] ={"\
     399varying vec3 normal, lightDir;\
     400uniform mat4 RotationMatrix;\
     401void main()\
     402{          \
     403  lightDir=normalize(vec3(gl_LightSource[0].position));\
     404  normal=normalize(gl_NormalMatrix*gl_Normal);\
     405  gl_Position = gl_ProjectionMatrix * \
     406  RotationMatrix*gl_ModelViewMatrix*gl_Vertex;\
     407}"};
     408
     409static const GLchar * fragment_shader[] ={"\
     410/* simple toon fragment shader */\
     411/* www.lighthouse3d.com        */\
     412\
     413varying vec3 normal, lightDir;\
     414\
     415void main()\
     416{\
     417        float intensity;\
     418        vec3 n;\
     419        vec4 color;\
     420\
     421        n = normalize(normal);\
     422        intensity = max(dot(lightDir,n),0.0);\
     423        if (intensity > 0.98)\
     424                color = vec4(0.8,0.8,0.8,1.0);\
     425        else if (intensity > 0.5)\
     426                color = vec4(0.4,0.4,0.8,1.0);\
     427        else if (intensity > 0.25)\
     428                color = vec4(0.2,0.2,0.4,1.0);\
     429        else\
     430                color = vec4(0.1,0.1,0.1,1.0);\
     431        gl_FragColor = color;\
     432}"};
     433
     434void setShaders()
     435{
     436  GLuint v, f;
     437
     438  v = glCreateShader(GL_VERTEX_SHADER);
     439  f = glCreateShader(GL_FRAGMENT_SHADER);
     440  glShaderSource(v, 1, vertex_shader, NULL);
     441  glShaderSource(f, 1, fragment_shader, NULL);
     442  glCompileShader(v);
     443  glCompileShader(f);
     444  p = glCreateProgram();
     445  glAttachShader(p,f);
     446  glAttachShader(p,v);
     447  glLinkProgram(p);
     448  glUseProgram(p);
     449}
     450
     451int main(int argc, char **argv)
     452{
     453  glutInit(&argc, argv);
     454  glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
     455  glutInitWindowSize(512, 512);
     456  glutInitWindowPosition((glutGet(GLUT_SCREEN_WIDTH)-512)/2,
     457                         (glutGet(GLUT_SCREEN_HEIGHT)-512)/2);
     458  glutCreateWindow("Use mouse to rotate");
    327459 
     460  trackball(cur, 0.0, 0.0, 0.0, 0.0);
     461
     462  glutDisplayFunc(display);
     463  glutReshapeFunc(reshape);
     464  glutMouseFunc(mouse);
     465  glutMotionFunc(motion);
     466  glutKeyboardFunc(processNormalKeys);
     467
     468  glEnable(GL_DEPTH_TEST);
     469  glClearColor(1.0,1.0,1.0,1.0);
     470  glewInit();
     471  if (!glewIsSupported("GL_VERSION_2_0"))
     472   {
     473     printf("GLSL not supported\n");
     474     exit(EXIT_FAILURE);
     475   }
     476  setShaders();
     477  glutMainLoop();
     478  return 0;
     479}
     480}}}
     481
     482