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/**
* Test OpenGL 2.0 dx/dy functions for texcoords.
* Brian Paul
* 2 May 2007
*
* NOTE: resize the window to observe how the partial derivatives of
* the texcoords change.
*/
#include <assert.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/glew.h>
#include <GL/gl.h>
#include <GL/glut.h>
#include <GL/glext.h>
#include "extfuncs.h"
#include "shaderutil.h"
static char *FragProgFile = NULL;
static char *VertProgFile = NULL;
static GLuint fragShader;
static GLuint vertShader;
static GLuint program;
static GLuint SphereList, RectList, CurList;
static GLint win = 0;
static GLboolean anim = GL_TRUE;
static GLfloat xRot = 0.0f, yRot = 0.0f;
static void
Redisplay(void)
{
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);
glCallList(CurList);
glPopMatrix();
glutSwapBuffers();
}
static void
Idle(void)
{
yRot = glutGet(GLUT_ELAPSED_TIME) * 0.1;
glutPostRedisplay();
}
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)
{
(void) x;
(void) y;
switch(key) {
case ' ':
case 'a':
anim = !anim;
if (anim)
glutIdleFunc(Idle);
else
glutIdleFunc(NULL);
break;
case 'o':
if (CurList == SphereList)
CurList = RectList;
else
CurList = SphereList;
break;
case 27:
CleanUp();
exit(0);
break;
}
glutPostRedisplay();
}
static void
SpecialKey(int key, int x, int y)
{
const GLfloat step = 3.0f;
(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
MakeSphere(void)
{
GLUquadricObj *obj = gluNewQuadric();
SphereList = glGenLists(1);
gluQuadricTexture(obj, GL_TRUE);
glNewList(SphereList, GL_COMPILE);
gluSphere(obj, 2.0f, 30, 15);
glEndList();
}
static void
MakeRect(void)
{
RectList = glGenLists(1);
glNewList(RectList, GL_COMPILE);
glBegin(GL_POLYGON);
glTexCoord2f(0, 0); glVertex2f(-2, -2);
glTexCoord2f(1, 0); glVertex2f( 2, -2);
glTexCoord2f(1, 1); glVertex2f( 2, 2);
glTexCoord2f(0, 1); glVertex2f(-2, 2);
glEnd();
glEndList();
}
static void
Init(void)
{
static const char *fragShaderText =
"void main() {\n"
" gl_FragColor = abs(dFdy(gl_TexCoord[0])) * 50.0;\n"
" // gl_FragColor = gl_TexCoord[0];\n"
"}\n";
static const char *vertShaderText =
"void main() {\n"
" gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
" gl_TexCoord[0] = gl_MultiTexCoord0;\n"
"}\n";
if (!ShadersSupported())
exit(1);
GetExtensionFuncs();
vertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
fragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
program = LinkShaders(vertShader, fragShader);
glUseProgram_func(program);
/*assert(glGetError() == 0);*/
glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
glEnable(GL_DEPTH_TEST);
MakeSphere();
MakeRect();
CurList = SphereList;
printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
assert(glIsProgram_func(program));
assert(glIsShader_func(fragShader));
assert(glIsShader_func(vertShader));
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);
glutInitWindowPosition( 0, 0);
glutInitWindowSize(200, 200);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
win = glutCreateWindow(argv[0]);
glewInit();
glutReshapeFunc(Reshape);
glutKeyboardFunc(Key);
glutSpecialFunc(SpecialKey);
glutDisplayFunc(Redisplay);
if (anim)
glutIdleFunc(Idle);
ParseOptions(argc, argv);
Init();
glutMainLoop();
return 0;
}
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