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/glew.h>
  14 #include <GL/gl.h>
  15 #include <GL/glut.h>
  16 #include <GL/glext.h>
  17 #include "extfuncs.h"
  18 #include "shaderutil.h"
  19
  20
  21 static GLint WinWidth = 300, WinHeight = 300;
  22 static char *FragProgFile = NULL;
  23 static char *VertProgFile = NULL;
  24 static GLuint fragShader;
  25 static GLuint vertShader;
  26 static GLuint program;
  27 static GLint win = 0;
  28 static GLint tex0;
  29 static GLenum Filter = GL_NEAREST;
  30
  31
  32 static void
  33 Redisplay(void)
  34 {
  35    glClear(GL_COLOR_BUFFER_BIT);
  36
  37    /* draw one point/sprite */
  38    glPushMatrix();
  39    glPointSize(60);
  40    glBegin(GL_POINTS);
  41    glVertex2f(WinWidth / 2.0f, WinHeight / 2.0f);
  42    glEnd();
  43    glPopMatrix();
  44
  45    glutSwapBuffers();
  46 }
  47
  48
  49 static void
  50 Reshape(int width, int height)
  51 {
  52    glViewport(0, 0, width, height);
  53    glMatrixMode(GL_PROJECTION);
  54    glLoadIdentity();
  55    glOrtho(0, width, 0, height, -1, 1);
  56
  57    glMatrixMode(GL_MODELVIEW);
  58    glLoadIdentity();
  59
  60    WinWidth = width;
  61    WinHeight = height;
  62 }
  63
  64
  65 static void
  66 CleanUp(void)
  67 {
  68    glDeleteShader_func(fragShader);
  69    glDeleteShader_func(vertShader);
  70    glDeleteProgram_func(program);
  71    glutDestroyWindow(win);
  72 }
  73
  74
  75 static void
  76 Key(unsigned char key, int x, int y)
  77 {
  78   (void) x;
  79   (void) y;
  80
  81    switch(key) {
  82    case 27:
  83       CleanUp();
  84       exit(0);
  85       break;
  86    }
  87    glutPostRedisplay();
  88 }
  89
  90
  91
  92 static void
  93 MakeTexture(void)
  94 {
  95 #define SZ 16
  96    GLubyte image[SZ][SZ][4];
  97    GLuint i, j;
  98
  99    for (i = 0; i < SZ; i++) {
 100       for (j = 0; j < SZ; j++) {
 101          if ((i + j) & 1) {
 102             image[i][j][0] = 0;
 103             image[i][j][1] = 0;
 104             image[i][j][2] = 0;
 105             image[i][j][3] = 255;
 106          }
 107          else {
 108             image[i][j][0] = j * 255 / (SZ-1);
 109             image[i][j][1] = i * 255 / (SZ-1);
 110             image[i][j][2] = 0;
 111             image[i][j][3] = 255;
 112          }
 113       }
 114    }
 115
 116    glActiveTexture(GL_TEXTURE0); /* unit 0 */
 117    glBindTexture(GL_TEXTURE_2D, 42);
 118    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, SZ, SZ, 0,
 119                 GL_RGBA, GL_UNSIGNED_BYTE, image);
 120    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, Filter);
 121    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, Filter);
 122    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 123    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 124 #undef SZ
 125 }
 126
 127
 128 static void
 129 Init(void)
 130 {
 131    static const char *fragShaderText =
 132       "#version 120 \n"
 133       "uniform sampler2D tex0; \n"
 134       "void main() { \n"
 135       "   gl_FragColor = texture2D(tex0, gl_PointCoord.xy, 0.0); \n"
 136       "}\n";
 137    static const char *vertShaderText =
 138       "void main() {\n"
 139       "   gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
 140       "}\n";
 141
 142    if (!ShadersSupported())
 143       exit(1);
 144
 145    GetExtensionFuncs();
 146
 147    vertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
 148    fragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
 149    program = LinkShaders(vertShader, fragShader);
 150
 151    glUseProgram_func(program);
 152
 153    tex0 = glGetUniformLocation_func(program, "tex0");
 154    printf("Uniforms: tex0: %d\n", tex0);
 155
 156    glUniform1i_func(tex0, 0); /* tex unit 0 */
 157
 158    /*assert(glGetError() == 0);*/
 159
 160    glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
 161
 162    printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
 163
 164    assert(glIsProgram_func(program));
 165    assert(glIsShader_func(fragShader));
 166    assert(glIsShader_func(vertShader));
 167
 168    MakeTexture();
 169
 170    glEnable(GL_POINT_SPRITE);
 171
 172    glColor3f(1, 0, 0);
 173 }
 174
 175
 176 static void
 177 ParseOptions(int argc, char *argv[])
 178 {
 179    int i;
 180    for (i = 1; i < argc; i++) {
 181       if (strcmp(argv[i], "-fs") == 0) {
 182          FragProgFile = argv[i+1];
 183       }
 184       else if (strcmp(argv[i], "-vs") == 0) {
 185          VertProgFile = argv[i+1];
 186       }
 187    }
 188 }
 189
 190
 191 int
 192 main(int argc, char *argv[])
 193 {
 194    glutInit(&argc, argv);
 195    glutInitWindowPosition( 0, 0);
 196    glutInitWindowSize(WinWidth, WinHeight);
 197    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
 198    win = glutCreateWindow(argv[0]);
 199    glewInit();
 200    glutReshapeFunc(Reshape);
 201    glutKeyboardFunc(Key);
 202    glutDisplayFunc(Redisplay);
 203    ParseOptions(argc, argv);
 204    Init();
 205    glutMainLoop();
 206    return 0;
 207 }