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/**
* Test GLSL 1.20 gl_PointCoord fragment program attribute.
* Brian Paul
* 11 Aug 2007
*/
#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 = 300, WinHeight = 300;
static char *FragProgFile = NULL;
static char *VertProgFile = NULL;
static GLuint fragShader;
static GLuint vertShader;
static GLuint program;
static GLint win = 0;
static GLint tex0;
static GLenum Filter = GL_NEAREST;
static void
Redisplay(void)
{
glClear(GL_COLOR_BUFFER_BIT);
/* draw one point/sprite */
glPushMatrix();
glPointSize(60);
glBegin(GL_POINTS);
glVertex2f(WinWidth / 2.0f, WinHeight / 2.0f);
glEnd();
glPopMatrix();
glutSwapBuffers();
}
static void
Reshape(int width, int height)
{
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, width, 0, height, -1, 1);
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 27:
CleanUp();
exit(0);
break;
}
glutPostRedisplay();
}
static void
MakeTexture(void)
{
#define SZ 16
GLubyte image[SZ][SZ][4];
GLuint i, j;
for (i = 0; i < SZ; i++) {
for (j = 0; j < SZ; j++) {
if ((i + j) & 1) {
image[i][j][0] = 0;
image[i][j][1] = 0;
image[i][j][2] = 0;
image[i][j][3] = 255;
}
else {
image[i][j][0] = j * 255 / (SZ-1);
image[i][j][1] = i * 255 / (SZ-1);
image[i][j][2] = 0;
image[i][j][3] = 255;
}
}
}
glActiveTexture(GL_TEXTURE0); /* unit 0 */
glBindTexture(GL_TEXTURE_2D, 42);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, SZ, SZ, 0,
GL_RGBA, GL_UNSIGNED_BYTE, image);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, Filter);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, Filter);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
#undef SZ
}
static void
Init(void)
{
static const char *fragShaderText =
"#version 120 \n"
"uniform sampler2D tex0; \n"
"void main() { \n"
" gl_FragColor = texture2D(tex0, gl_PointCoord.xy, 0.0); \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);
tex0 = glGetUniformLocation(program, "tex0");
printf("Uniforms: tex0: %d\n", tex0);
glUniform1i(tex0, 0); /* tex unit 0 */
/*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));
MakeTexture();
glEnable(GL_POINT_SPRITE);
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(WinWidth, WinHeight);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
win = glutCreateWindow(argv[0]);
glewInit();
glutReshapeFunc(Reshape);
glutKeyboardFunc(Key);
glutDisplayFunc(Redisplay);
ParseOptions(argc, argv);
Init();
glutMainLoop();
return 0;
}
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