skinning.c revision 32001f49 
1/**
2 * Vertex "skinning" example.
3 * The idea is there are multiple modeling matrices applied to every
4 * vertex.  Weighting values in [0,1] control the influence of each
5 * matrix on each vertex.
6 *
7 * 4 Nov 2008
8 */
9
10#include <assert.h>
11#include <string.h>
12#include <stdio.h>
13#include <stdlib.h>
14#include <math.h>
15#include <GL/glew.h>
16#include "glut_wrap.h"
17#include "shaderutil.h"
18
19#ifndef M_PI
20#define M_PI 3.1415926535
21#endif
22
23static char *FragProgFile = "skinning.frag";
24static char *VertProgFile = "skinning.vert";
25
26/* program/shader objects */
27static GLuint fragShader;
28static GLuint vertShader;
29static GLuint program;
30
31
32static GLint win = 0;
33static GLboolean Anim = GL_TRUE;
34static GLboolean WireFrame = GL_TRUE;
35static GLfloat xRot = 0.0f, yRot = 90.0f, zRot = 0.0f;
36
37#define NUM_MATS 2
38
39static GLfloat Matrices[NUM_MATS][16];
40static GLint uMat0, uMat1;
41static GLint WeightAttr;
42
43
44static void
45Idle(void)
46{
47   yRot = 90 + glutGet(GLUT_ELAPSED_TIME) * 0.005;
48   glutPostRedisplay();
49}
50
51
52static void
53Cylinder(GLfloat length, GLfloat radius, GLint slices, GLint stacks)
54{
55   float dw = 1.0 / (stacks - 1);
56   float dz = length / stacks;
57   int i, j;
58
59   for (j = 0; j < stacks; j++) {
60      float w0 = j * dw;
61      float z0 = j * dz;
62
63      glBegin(GL_TRIANGLE_STRIP);
64      for (i = 0; i < slices; i++) {
65         float a = (float) i / (slices - 1) * M_PI * 2.0;
66         float x = radius * cos(a);
67         float y = radius * sin(a);
68         glVertexAttrib1f(WeightAttr, w0);
69         glNormal3f(x, y, 0.0);
70         glVertex3f(x, y, z0);
71
72         glVertexAttrib1f(WeightAttr, w0 + dw);
73         glNormal3f(x, y, 0.0);
74         glVertex3f(x, y, z0 + dz);
75      }
76      glEnd();
77   }
78}
79
80
81/**
82 * Update/animate the two matrices.  One rotates, the other scales.
83 */
84static void
85UpdateMatrices(void)
86{
87   GLfloat t = glutGet(GLUT_ELAPSED_TIME) * 0.0025;
88   GLfloat scale = 0.5 * (1.1 + sin(0.5 * t));
89   GLfloat rot = cos(t) * 90.0;
90
91   glPushMatrix();
92   glLoadIdentity();
93   glScalef(1.0, scale, 1.0);
94   glGetFloatv(GL_MODELVIEW_MATRIX, Matrices[0]);
95   glPopMatrix();
96
97   glPushMatrix();
98   glLoadIdentity();
99   glRotatef(rot, 0, 0, 1);
100   glGetFloatv(GL_MODELVIEW_MATRIX, Matrices[1]);
101   glPopMatrix();
102}
103
104
105static void
106Redisplay(void)
107{
108   UpdateMatrices();
109
110   glUniformMatrix4fv(uMat0, 1, GL_FALSE, Matrices[0]);
111   glUniformMatrix4fv(uMat1, 1, GL_FALSE, Matrices[1]);
112
113   if (WireFrame)
114      glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
115   else
116      glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
117
118   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
119
120   glPushMatrix();
121   glRotatef(xRot, 1.0f, 0.0f, 0.0f);
122   glRotatef(yRot, 0.0f, 1.0f, 0.0f);
123   glRotatef(zRot, 0.0f, 0.0f, 1.0f);
124
125   glPushMatrix();
126   glTranslatef(0, 0, -2.5);
127   Cylinder(5.0, 1.0, 10, 20);
128   glPopMatrix();
129
130   glPopMatrix();
131
132   glutSwapBuffers();
133}
134
135
136static void
137Reshape(int width, int height)
138{
139   glViewport(0, 0, width, height);
140   glMatrixMode(GL_PROJECTION);
141   glLoadIdentity();
142   glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
143   glMatrixMode(GL_MODELVIEW);
144   glLoadIdentity();
145   glTranslatef(0.0f, 0.0f, -15.0f);
146}
147
148
149static void
150CleanUp(void)
151{
152   glDeleteShader(fragShader);
153   glDeleteShader(vertShader);
154   glDeleteProgram(program);
155   glutDestroyWindow(win);
156}
157
158
159static void
160Key(unsigned char key, int x, int y)
161{
162   const GLfloat step = 2.0;
163  (void) x;
164  (void) y;
165
166   switch(key) {
167   case 'a':
168      Anim = !Anim;
169      if (Anim)
170         glutIdleFunc(Idle);
171      else
172         glutIdleFunc(NULL);
173      break;
174   case 'w':
175      WireFrame = !WireFrame;
176      break;
177   case 'z':
178      zRot += step;
179      break;
180   case 'Z':
181      zRot -= step;
182      break;
183   case 27:
184      CleanUp();
185      exit(0);
186      break;
187   }
188   glutPostRedisplay();
189}
190
191
192static void
193SpecialKey(int key, int x, int y)
194{
195   const GLfloat step = 2.0;
196
197  (void) x;
198  (void) y;
199
200   switch(key) {
201   case GLUT_KEY_UP:
202      xRot += step;
203      break;
204   case GLUT_KEY_DOWN:
205      xRot -= step;
206      break;
207   case GLUT_KEY_LEFT:
208      yRot -= step;
209      break;
210   case GLUT_KEY_RIGHT:
211      yRot += step;
212      break;
213   }
214   glutPostRedisplay();
215}
216
217
218
219static void
220Init(void)
221{
222   if (!ShadersSupported())
223      exit(1);
224
225   vertShader = CompileShaderFile(GL_VERTEX_SHADER, VertProgFile);
226   fragShader = CompileShaderFile(GL_FRAGMENT_SHADER, FragProgFile);
227   program = LinkShaders(vertShader, fragShader);
228
229   glUseProgram(program);
230
231   uMat0 = glGetUniformLocation(program, "mat0");
232   uMat1 = glGetUniformLocation(program, "mat1");
233
234   WeightAttr = glGetAttribLocation(program, "weight");
235
236   assert(glGetError() == 0);
237
238   glClearColor(0.4f, 0.4f, 0.8f, 0.0f);
239
240   glEnable(GL_DEPTH_TEST);
241
242   glColor3f(1, 0, 0);
243}
244
245
246static void
247ParseOptions(int argc, char *argv[])
248{
249   int i;
250   for (i = 1; i < argc; i++) {
251      if (strcmp(argv[i], "-fs") == 0) {
252         FragProgFile = argv[i+1];
253      }
254      else if (strcmp(argv[i], "-vs") == 0) {
255         VertProgFile = argv[i+1];
256      }
257   }
258}
259
260
261int
262main(int argc, char *argv[])
263{
264   glutInit(&argc, argv);
265   glutInitWindowSize(500, 500);
266   glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
267   win = glutCreateWindow(argv[0]);
268   glewInit();
269   glutReshapeFunc(Reshape);
270   glutKeyboardFunc(Key);
271   glutSpecialFunc(SpecialKey);
272   glutDisplayFunc(Redisplay);
273   ParseOptions(argc, argv);
274   Init();
275   if (Anim)
276      glutIdleFunc(Idle);
277   glutMainLoop();
278   return 0;
279}
280
281