--- /dev/null
+/**
+ * Vertex "skinning" example.
+ * The idea is there are multiple modeling matrices applied to every
+ * vertex. Weighting values in [0,1] control the influence of each
+ * matrix on each vertex.
+ *
+ * 4 Nov 2008
+ */
+
+#include <assert.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <GL/gl.h>
+#include <GL/glut.h>
+#include <GL/glext.h>
+#include "extfuncs.h"
+#include "shaderutil.h"
+
+
+static char *FragProgFile = "skinning.frag";
+static char *VertProgFile = "skinning.vert";
+
+/* program/shader objects */
+static GLuint fragShader;
+static GLuint vertShader;
+static GLuint program;
+
+
+static GLint win = 0;
+static GLboolean Anim = GL_TRUE;
+static GLboolean WireFrame = GL_TRUE;
+static GLfloat xRot = 0.0f, yRot = 90.0f, zRot = 0.0f;
+
+#define NUM_MATS 2
+
+static GLfloat Matrices[NUM_MATS][16];
+static GLint uMat0, uMat1;
+static GLint WeightAttr;
+
+
+static void
+Idle(void)
+{
+ yRot = 90 + glutGet(GLUT_ELAPSED_TIME) * 0.005;
+ glutPostRedisplay();
+}
+
+
+static void
+Cylinder(GLfloat length, GLfloat radius, GLint slices, GLint stacks)
+{
+ float dw = 1.0 / (stacks - 1);
+ float dz = length / stacks;
+ int i, j;
+
+ for (j = 0; j < stacks; j++) {
+ float w0 = j * dw;
+ float z0 = j * dz;
+
+ glBegin(GL_TRIANGLE_STRIP);
+ for (i = 0; i < slices; i++) {
+ float a = (float) i / (slices - 1) * M_PI * 2.0;
+ float x = radius * cos(a);
+ float y = radius * sin(a);
+ glVertexAttrib1f_func(WeightAttr, w0);
+ glNormal3f(x, y, 0.0);
+ glVertex3f(x, y, z0);
+
+ glVertexAttrib1f_func(WeightAttr, w0 + dw);
+ glNormal3f(x, y, 0.0);
+ glVertex3f(x, y, z0 + dz);
+ }
+ glEnd();
+ }
+}
+
+
+/**
+ * Update/animate the two matrices. One rotates, the other scales.
+ */
+static void
+UpdateMatrices(void)
+{
+ GLfloat t = glutGet(GLUT_ELAPSED_TIME) * 0.0025;
+ GLfloat scale = 0.5 * (1.1 + sin(0.5 * t));
+ GLfloat rot = cos(t) * 90.0;
+
+ glPushMatrix();
+ glLoadIdentity();
+ glScalef(1.0, scale, 1.0);
+ glGetFloatv(GL_MODELVIEW_MATRIX, Matrices[0]);
+ glPopMatrix();
+
+ glPushMatrix();
+ glLoadIdentity();
+ glRotatef(rot, 0, 0, 1);
+ glGetFloatv(GL_MODELVIEW_MATRIX, Matrices[1]);
+ glPopMatrix();
+}
+
+
+static void
+Redisplay(void)
+{
+ UpdateMatrices();
+
+ glUniformMatrix4fv_func(uMat0, 1, GL_FALSE, Matrices[0]);
+ glUniformMatrix4fv_func(uMat1, 1, GL_FALSE, Matrices[1]);
+
+ if (WireFrame)
+ glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+ else
+ glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
+
+ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+ glPushMatrix();
+ glRotatef(xRot, 1.0f, 0.0f, 0.0f);
+ glRotatef(yRot, 0.0f, 1.0f, 0.0f);
+ glRotatef(zRot, 0.0f, 0.0f, 1.0f);
+
+ glPushMatrix();
+ glTranslatef(0, 0, -2.5);
+ Cylinder(5.0, 1.0, 10, 20);
+ glPopMatrix();
+
+ glPopMatrix();
+
+ glutSwapBuffers();
+}
+
+
+static void
+Reshape(int width, int height)
+{
+ glViewport(0, 0, width, height);
+ glMatrixMode(GL_PROJECTION);
+ glLoadIdentity();
+ glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
+ glMatrixMode(GL_MODELVIEW);
+ glLoadIdentity();
+ glTranslatef(0.0f, 0.0f, -15.0f);
+}
+
+
+static void
+CleanUp(void)
+{
+ glDeleteShader_func(fragShader);
+ glDeleteShader_func(vertShader);
+ glDeleteProgram_func(program);
+ glutDestroyWindow(win);
+}
+
+
+static void
+Key(unsigned char key, int x, int y)
+{
+ const GLfloat step = 2.0;
+ (void) x;
+ (void) y;
+
+ switch(key) {
+ case 'a':
+ Anim = !Anim;
+ if (Anim)
+ glutIdleFunc(Idle);
+ else
+ glutIdleFunc(NULL);
+ break;
+ case 'w':
+ WireFrame = !WireFrame;
+ break;
+ case 'z':
+ zRot += step;
+ break;
+ case 'Z':
+ zRot -= step;
+ break;
+ case 27:
+ CleanUp();
+ exit(0);
+ break;
+ }
+ glutPostRedisplay();
+}
+
+
+static void
+SpecialKey(int key, int x, int y)
+{
+ const GLfloat step = 2.0;
+
+ (void) x;
+ (void) y;
+
+ switch(key) {
+ case GLUT_KEY_UP:
+ xRot += step;
+ break;
+ case GLUT_KEY_DOWN:
+ xRot -= step;
+ break;
+ case GLUT_KEY_LEFT:
+ yRot -= step;
+ break;
+ case GLUT_KEY_RIGHT:
+ yRot += step;
+ break;
+ }
+ glutPostRedisplay();
+}
+
+
+
+static void
+Init(void)
+{
+ if (!ShadersSupported())
+ exit(1);
+
+ GetExtensionFuncs();
+
+ vertShader = CompileShaderFile(GL_VERTEX_SHADER, VertProgFile);
+ fragShader = CompileShaderFile(GL_FRAGMENT_SHADER, FragProgFile);
+ program = LinkShaders(vertShader, fragShader);
+
+ glUseProgram_func(program);
+
+ uMat0 = glGetUniformLocation_func(program, "mat0");
+ uMat1 = glGetUniformLocation_func(program, "mat1");
+
+ WeightAttr = glGetAttribLocation_func(program, "weight");
+
+ assert(glGetError() == 0);
+
+ glClearColor(0.4f, 0.4f, 0.8f, 0.0f);
+
+ glEnable(GL_DEPTH_TEST);
+
+ glColor3f(1, 0, 0);
+}
+
+
+static void
+ParseOptions(int argc, char *argv[])
+{
+ int i;
+ for (i = 1; i < argc; i++) {
+ if (strcmp(argv[i], "-fs") == 0) {
+ FragProgFile = argv[i+1];
+ }
+ else if (strcmp(argv[i], "-vs") == 0) {
+ VertProgFile = argv[i+1];
+ }
+ }
+}
+
+
+int
+main(int argc, char *argv[])
+{
+ glutInit(&argc, argv);
+ glutInitWindowSize(500, 500);
+ glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
+ win = glutCreateWindow(argv[0]);
+ glutReshapeFunc(Reshape);
+ glutKeyboardFunc(Key);
+ glutSpecialFunc(SpecialKey);
+ glutDisplayFunc(Redisplay);
+ ParseOptions(argc, argv);
+ Init();
+ if (Anim)
+ glutIdleFunc(Idle);
+ glutMainLoop();
+ return 0;
+}
+