182 lines
3.4 KiB
C
182 lines
3.4 KiB
C
/**
|
|
* Test GLSL gl_FragCoord fragment program attribute.
|
|
* Color the quad's fragments according to their window position.
|
|
*
|
|
* Brian Paul
|
|
* 20 Nov 2008
|
|
*/
|
|
|
|
|
|
#include <assert.h>
|
|
#include <string.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <math.h>
|
|
#include <GL/glew.h>
|
|
#include <GL/glut.h>
|
|
#include "shaderutil.h"
|
|
|
|
|
|
static GLint WinWidth = 200, WinHeight = 200;
|
|
static char *FragProgFile = NULL;
|
|
static char *VertProgFile = NULL;
|
|
static GLuint fragShader;
|
|
static GLuint vertShader;
|
|
static GLuint program;
|
|
static GLint win = 0;
|
|
static GLboolean Anim = GL_TRUE;
|
|
static GLfloat PosX = 0.0, PosY = 0.0;
|
|
|
|
|
|
static void
|
|
Idle(void)
|
|
{
|
|
float r = (WinWidth < WinHeight) ? WinWidth : WinHeight;
|
|
float a = glutGet(GLUT_ELAPSED_TIME) * 0.001;
|
|
r *= 0.25;
|
|
PosX = WinWidth / 2 + r * cos(a);
|
|
PosY = WinHeight / 2 + r * sin(a);
|
|
|
|
glutPostRedisplay();
|
|
}
|
|
|
|
|
|
static void
|
|
Redisplay(void)
|
|
{
|
|
glClear(GL_COLOR_BUFFER_BIT);
|
|
|
|
glPushMatrix();
|
|
glTranslatef(PosX, PosY, 0.0);
|
|
#if 0
|
|
glBegin(GL_POLYGON);
|
|
glVertex2f(-50, -50);
|
|
glVertex2f( 50, -50);
|
|
glVertex2f( 50, 50);
|
|
glVertex2f(-50, 50);
|
|
glEnd();
|
|
#else
|
|
glutSolidSphere(50, 20, 10);
|
|
#endif
|
|
glPopMatrix();
|
|
|
|
glutSwapBuffers();
|
|
}
|
|
|
|
|
|
static void
|
|
Reshape(int width, int height)
|
|
{
|
|
glViewport(0, 0, width, height);
|
|
glMatrixMode(GL_PROJECTION);
|
|
glLoadIdentity();
|
|
glOrtho(0, width, 0, height, -55, 55);
|
|
|
|
glMatrixMode(GL_MODELVIEW);
|
|
glLoadIdentity();
|
|
|
|
WinWidth = width;
|
|
WinHeight = height;
|
|
}
|
|
|
|
|
|
static void
|
|
CleanUp(void)
|
|
{
|
|
glDeleteShader(fragShader);
|
|
glDeleteShader(vertShader);
|
|
glDeleteProgram(program);
|
|
glutDestroyWindow(win);
|
|
}
|
|
|
|
|
|
static void
|
|
Key(unsigned char key, int x, int y)
|
|
{
|
|
(void) x;
|
|
(void) y;
|
|
|
|
switch(key) {
|
|
case ' ':
|
|
case 'a':
|
|
Anim = !Anim;
|
|
glutIdleFunc(Anim ? Idle : NULL);
|
|
break;
|
|
case 27:
|
|
CleanUp();
|
|
exit(0);
|
|
break;
|
|
}
|
|
glutPostRedisplay();
|
|
}
|
|
|
|
|
|
static void
|
|
Init(void)
|
|
{
|
|
static const char *fragShaderText =
|
|
"void main() { \n"
|
|
" vec4 scale = vec4(.005, 0.005, 0.5, 1.0);\n"
|
|
" gl_FragColor = gl_FragCoord * scale; \n"
|
|
"}\n";
|
|
static const char *vertShaderText =
|
|
"void main() {\n"
|
|
" gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
|
|
"}\n";
|
|
|
|
if (!ShadersSupported())
|
|
exit(1);
|
|
|
|
vertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
|
|
fragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
|
|
program = LinkShaders(vertShader, fragShader);
|
|
|
|
glUseProgram(program);
|
|
|
|
/*assert(glGetError() == 0);*/
|
|
|
|
glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
|
|
|
|
printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
|
|
|
|
assert(glIsProgram(program));
|
|
assert(glIsShader(fragShader));
|
|
assert(glIsShader(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);
|
|
glutInitWindowSize(WinWidth, WinHeight);
|
|
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
|
|
win = glutCreateWindow(argv[0]);
|
|
glewInit();
|
|
glutReshapeFunc(Reshape);
|
|
glutKeyboardFunc(Key);
|
|
glutDisplayFunc(Redisplay);
|
|
ParseOptions(argc, argv);
|
|
Init();
|
|
glutIdleFunc(Anim ? Idle : NULL);
|
|
glutMainLoop();
|
|
return 0;
|
|
}
|