Changes between Version 17 and Version 18 of tutorial

Timestamp:

Jun 28, 2013, 11:18:52 AM (11 years ago)

Author:

leon

Comment:

teapot

tutorial

@@ -325 +325 @@
   What happens if we don't enable temperature vertex array? Confer [attachment:temperature.c] attached if having troubles.
  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.
+
+
+== Interactivity ==
+[[Image(teapot.png,right)]]
+
+Assemble the following Utah teapot model and attached virtual [attachment:trackball.h] and [attachment:trackball.c] sources from SGI. We use 
+{{{
+#!c
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <GL/glew.h>
+#include <GL/glut.h>
+#include "trackball.h"
+
+GLuint p; // program needs to be global!
+float lpos[4] = {1, 0.5, 1, 0};
+GLfloat m[4][4]; // modelview rotation matrix
+float last[4], cur[4]; // rotation tracking quaternions 
+int width, height, beginx, beginy;
+float p1x, p1y, p2x, p2y;
+
+void display(void) {
+  GLuint location = glGetUniformLocation(p, "RotationMatrix");
+  build_rotmatrix(m, cur);  
+  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+  glLightfv(GL_LIGHT0, GL_POSITION, lpos);
+  if( location >= 0 )
+    glUniformMatrix4fv(location, 1, GL_FALSE, &m[0][0]);
+  glutSolidTeapot(0.6);
+  glutSwapBuffers();
+}
+
+
+void processNormalKeys(unsigned char key, int x, int y) {
+        if (key == 27) 
+                exit(0);
+}
+
+void mouse(int button,int state, int x, int y)   
+{
+  beginx = x;
+  beginy = y;
+}
+
+void motion(int x,int y)   
+{
+  p1x = (2.0*beginx - width)/width;
+  p1y = (height - 2.0*beginy)/height;
+  p2x = (2.0 * x - width) / width;
+  p2y = (height - 2.0 * y) / height;
+  trackball(last, p1x, p1y, p2x, p2y);   
+  add_quats(last, cur, cur);   
+  beginx = x;
+  beginy = y;
+  glutPostRedisplay();   
+}
+
+void reshape (int w, int h)
+{
+  double l = 1;
+  width=w;  height=h;
+  glViewport (0, 0, w, h);
+  glMatrixMode (GL_PROJECTION);
+  glLoadIdentity();
+  glOrtho(-l, l, -l, l, -l, l);
+  glMatrixMode(GL_MODELVIEW);
+  glLoadIdentity();
+}
+
+static const GLchar * vertex_shader[] ={"\
+varying vec3 normal, lightDir;\
+uniform mat4 RotationMatrix;\
+void main()\
+{          \
+  lightDir=normalize(vec3(gl_LightSource[0].position));\
+  normal=normalize(gl_NormalMatrix*gl_Normal);\
+  gl_Position = gl_ProjectionMatrix * \
+  RotationMatrix*gl_ModelViewMatrix*gl_Vertex;\
+}"};
+
+static const GLchar * fragment_shader[] ={"\
+/* simple toon fragment shader */\
+/* www.lighthouse3d.com        */\
+\
+varying vec3 normal, lightDir;\
+\
+void main()\
+{\
+        float intensity;\
+        vec3 n;\
+        vec4 color;\
+\
+        n = normalize(normal);\
+        intensity = max(dot(lightDir,n),0.0);\
+        if (intensity > 0.98)\
+                color = vec4(0.8,0.8,0.8,1.0);\
+        else if (intensity > 0.5)\
+                color = vec4(0.4,0.4,0.8,1.0);\
+        else if (intensity > 0.25)\
+                color = vec4(0.2,0.2,0.4,1.0);\
+        else\
+                color = vec4(0.1,0.1,0.1,1.0);\
+        gl_FragColor = color;\
+}"};
+
+void setShaders()
+{
+  GLuint v, f;
+
+  v = glCreateShader(GL_VERTEX_SHADER);
+  f = glCreateShader(GL_FRAGMENT_SHADER);
+  glShaderSource(v, 1, vertex_shader, NULL);
+  glShaderSource(f, 1, fragment_shader, NULL);
+  glCompileShader(v);
+  glCompileShader(f);
+  p = glCreateProgram();
+  glAttachShader(p,f);
+  glAttachShader(p,v);
+  glLinkProgram(p);
+  glUseProgram(p);
+}
+
+int main(int argc, char **argv)
+{
+  glutInit(&argc, argv);
+  glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
+  glutInitWindowSize(512, 512);
+  glutInitWindowPosition((glutGet(GLUT_SCREEN_WIDTH)-512)/2,
+                         (glutGet(GLUT_SCREEN_HEIGHT)-512)/2);
+  glutCreateWindow("Use mouse to rotate");
   
+  trackball(cur, 0.0, 0.0, 0.0, 0.0);
+
+  glutDisplayFunc(display);
+  glutReshapeFunc(reshape);
+  glutMouseFunc(mouse);
+  glutMotionFunc(motion);
+  glutKeyboardFunc(processNormalKeys);
+
+  glEnable(GL_DEPTH_TEST);
+  glClearColor(1.0,1.0,1.0,1.0);
+  glewInit();
+  if (!glewIsSupported("GL_VERSION_2_0"))
+   {
+     printf("GLSL not supported\n");
+     exit(EXIT_FAILURE);
+   }
+  setShaders();
+  glutMainLoop();
+  return 0;
+}
+}}}
+
+