progs/glsl/pointcoord.c

   1 /**
   2  * Test GLSL 1.20 gl_PointCoord fragment program attribute.
   3  * Brian Paul
   4  * 11 Aug 2007
   5  */
   6
   7
   8 #include <assert.h>
   9 #include <string.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <math.h>
  13 #include <GL/gl.h>
  14 #include <GL/glut.h>
  15 #include <GL/glext.h>
  16 #include "extfuncs.h"
  17 #include "shaderutil.h"
  18
  19
  20 static GLint WinWidth = 300, WinHeight = 300;
  21 static char *FragProgFile = NULL;
  22 static char *VertProgFile = NULL;
  23 static GLuint fragShader;
  24 static GLuint vertShader;
  25 static GLuint program;
  26 static GLint win = 0;
  27 static GLint tex0;
  28 static GLenum Filter = GL_NEAREST;
  29
  30
  31 static void
  32 Redisplay(void)
  33 {
  34    glClear(GL_COLOR_BUFFER_BIT);
  35
  36    /* draw one point/sprite */
  37    glPushMatrix();
  38    glPointSize(60);
  39    glBegin(GL_POINTS);
  40    glVertex2f(WinWidth / 2.0f, WinHeight / 2.0f);
  41    glEnd();
  42    glPopMatrix();
  43
  44    glutSwapBuffers();
  45 }
  46
  47
  48 static void
  49 Reshape(int width, int height)
  50 {
  51    glViewport(0, 0, width, height);
  52    glMatrixMode(GL_PROJECTION);
  53    glLoadIdentity();
  54    glOrtho(0, width, 0, height, -1, 1);
  55
  56    glMatrixMode(GL_MODELVIEW);
  57    glLoadIdentity();
  58
  59    WinWidth = width;
  60    WinHeight = height;
  61 }
  62
  63
  64 static void
  65 CleanUp(void)
  66 {
  67    glDeleteShader_func(fragShader);
  68    glDeleteShader_func(vertShader);
  69    glDeleteProgram_func(program);
  70    glutDestroyWindow(win);
  71 }
  72
  73
  74 static void
  75 Key(unsigned char key, int x, int y)
  76 {
  77   (void) x;
  78   (void) y;
  79
  80    switch(key) {
  81    case 27:
  82       CleanUp();
  83       exit(0);
  84       break;
  85    }
  86    glutPostRedisplay();
  87 }
  88
  89
  90
  91 static void
  92 MakeTexture(void)
  93 {
  94 #define SZ 16
  95    GLubyte image[SZ][SZ][4];
  96    GLuint i, j;
  97
  98    for (i = 0; i < SZ; i++) {
  99       for (j = 0; j < SZ; j++) {
 100          if ((i + j) & 1) {
 101             image[i][j][0] = 0;
 102             image[i][j][1] = 0;
 103             image[i][j][2] = 0;
 104             image[i][j][3] = 255;
 105          }
 106          else {
 107             image[i][j][0] = j * 255 / (SZ-1);
 108             image[i][j][1] = i * 255 / (SZ-1);
 109             image[i][j][2] = 0;
 110             image[i][j][3] = 255;
 111          }
 112       }
 113    }
 114
 115    glActiveTexture(GL_TEXTURE0); /* unit 0 */
 116    glBindTexture(GL_TEXTURE_2D, 42);
 117    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, SZ, SZ, 0,
 118                 GL_RGBA, GL_UNSIGNED_BYTE, image);
 119    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, Filter);
 120    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, Filter);
 121    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 122    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 123 #undef SZ
 124 }
 125
 126
 127 static void
 128 Init(void)
 129 {
 130    static const char *fragShaderText =
 131       "#version 120 \n"
 132       "uniform sampler2D tex0; \n"
 133       "void main() { \n"
 134       "   gl_FragColor = texture2D(tex0, gl_PointCoord.xy, 0.0); \n"
 135       "}\n";
 136    static const char *vertShaderText =
 137       "void main() {\n"
 138       "   gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
 139       "}\n";
 140
 141    if (!ShadersSupported())
 142       exit(1);
 143
 144    GetExtensionFuncs();
 145
 146    vertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
 147    fragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
 148    program = LinkShaders(vertShader, fragShader);
 149
 150    glUseProgram_func(program);
 151
 152    tex0 = glGetUniformLocation_func(program, "tex0");
 153    printf("Uniforms: tex0: %d\n", tex0);
 154
 155    glUniform1i_func(tex0, 0); /* tex unit 0 */
 156
 157    /*assert(glGetError() == 0);*/
 158
 159    glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
 160
 161    printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
 162
 163    assert(glIsProgram_func(program));
 164    assert(glIsShader_func(fragShader));
 165    assert(glIsShader_func(vertShader));
 166
 167    MakeTexture();
 168
 169    glEnable(GL_POINT_SPRITE);
 170
 171    glColor3f(1, 0, 0);
 172 }
 173
 174
 175 static void
 176 ParseOptions(int argc, char *argv[])
 177 {
 178    int i;
 179    for (i = 1; i < argc; i++) {
 180       if (strcmp(argv[i], "-fs") == 0) {
 181          FragProgFile = argv[i+1];
 182       }
 183       else if (strcmp(argv[i], "-vs") == 0) {
 184          VertProgFile = argv[i+1];
 185       }
 186    }
 187 }
 188
 189
 190 int
 191 main(int argc, char *argv[])
 192 {
 193    glutInit(&argc, argv);
 194    glutInitWindowPosition( 0, 0);
 195    glutInitWindowSize(WinWidth, WinHeight);
 196    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
 197    win = glutCreateWindow(argv[0]);
 198    glutReshapeFunc(Reshape);
 199    glutKeyboardFunc(Key);
 200    glutDisplayFunc(Redisplay);
 201    ParseOptions(argc, argv);
 202    Init();
 203    glutMainLoop();
 204    return 0;
 205 }