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/glut.h>
  15 #include "shaderutil.h"
  16
  17
  18 static GLint WinWidth = 300, WinHeight = 300;
  19 static char *FragProgFile = NULL;
  20 static char *VertProgFile = NULL;
  21 static GLuint fragShader;
  22 static GLuint vertShader;
  23 static GLuint program;
  24 static GLint win = 0;
  25 static GLint tex0;
  26 static GLenum Filter = GL_NEAREST;
  27
  28
  29 static void
  30 Redisplay(void)
  31 {
  32    glClear(GL_COLOR_BUFFER_BIT);
  33
  34    /* draw one point/sprite */
  35    glPushMatrix();
  36    glPointSize(60);
  37    glBegin(GL_POINTS);
  38    glVertex2f(WinWidth / 2.0f, WinHeight / 2.0f);
  39    glEnd();
  40    glPopMatrix();
  41
  42    glutSwapBuffers();
  43 }
  44
  45
  46 static void
  47 Reshape(int width, int height)
  48 {
  49    glViewport(0, 0, width, height);
  50    glMatrixMode(GL_PROJECTION);
  51    glLoadIdentity();
  52    glOrtho(0, width, 0, height, -1, 1);
  53
  54    glMatrixMode(GL_MODELVIEW);
  55    glLoadIdentity();
  56
  57    WinWidth = width;
  58    WinHeight = height;
  59 }
  60
  61
  62 static void
  63 CleanUp(void)
  64 {
  65    glDeleteShader(fragShader);
  66    glDeleteShader(vertShader);
  67    glDeleteProgram(program);
  68    glutDestroyWindow(win);
  69 }
  70
  71
  72 static void
  73 Key(unsigned char key, int x, int y)
  74 {
  75   (void) x;
  76   (void) y;
  77
  78    switch(key) {
  79    case 27:
  80       CleanUp();
  81       exit(0);
  82       break;
  83    }
  84    glutPostRedisplay();
  85 }
  86
  87
  88
  89 static void
  90 MakeTexture(void)
  91 {
  92 #define SZ 16
  93    GLubyte image[SZ][SZ][4];
  94    GLuint i, j;
  95
  96    for (i = 0; i < SZ; i++) {
  97       for (j = 0; j < SZ; j++) {
  98          if ((i + j) & 1) {
  99             image[i][j][0] = 0;
 100             image[i][j][1] = 0;
 101             image[i][j][2] = 0;
 102             image[i][j][3] = 255;
 103          }
 104          else {
 105             image[i][j][0] = j * 255 / (SZ-1);
 106             image[i][j][1] = i * 255 / (SZ-1);
 107             image[i][j][2] = 0;
 108             image[i][j][3] = 255;
 109          }
 110       }
 111    }
 112
 113    glActiveTexture(GL_TEXTURE0); /* unit 0 */
 114    glBindTexture(GL_TEXTURE_2D, 42);
 115    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, SZ, SZ, 0,
 116                 GL_RGBA, GL_UNSIGNED_BYTE, image);
 117    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, Filter);
 118    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, Filter);
 119    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 120    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 121 #undef SZ
 122 }
 123
 124
 125 static void
 126 Init(void)
 127 {
 128    static const char *fragShaderText =
 129       "#version 120 \n"
 130       "uniform sampler2D tex0; \n"
 131       "void main() { \n"
 132       "   gl_FragColor = texture2D(tex0, gl_PointCoord.xy, 0.0); \n"
 133       "}\n";
 134    static const char *vertShaderText =
 135       "void main() {\n"
 136       "   gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
 137       "}\n";
 138
 139    if (!ShadersSupported())
 140       exit(1);
 141
 142    vertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
 143    fragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
 144    program = LinkShaders(vertShader, fragShader);
 145
 146    glUseProgram(program);
 147
 148    tex0 = glGetUniformLocation(program, "tex0");
 149    printf("Uniforms: tex0: %d\n", tex0);
 150
 151    glUniform1i(tex0, 0); /* tex unit 0 */
 152
 153    /*assert(glGetError() == 0);*/
 154
 155    glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
 156
 157    printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
 158
 159    assert(glIsProgram(program));
 160    assert(glIsShader(fragShader));
 161    assert(glIsShader(vertShader));
 162
 163    MakeTexture();
 164
 165    glEnable(GL_POINT_SPRITE);
 166
 167    glColor3f(1, 0, 0);
 168 }
 169
 170
 171 static void
 172 ParseOptions(int argc, char *argv[])
 173 {
 174    int i;
 175    for (i = 1; i < argc; i++) {
 176       if (strcmp(argv[i], "-fs") == 0) {
 177          FragProgFile = argv[i+1];
 178       }
 179       else if (strcmp(argv[i], "-vs") == 0) {
 180          VertProgFile = argv[i+1];
 181       }
 182    }
 183 }
 184
 185
 186 int
 187 main(int argc, char *argv[])
 188 {
 189    glutInit(&argc, argv);
 190    glutInitWindowSize(WinWidth, WinHeight);
 191    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
 192    win = glutCreateWindow(argv[0]);
 193    glewInit();
 194    glutReshapeFunc(Reshape);
 195    glutKeyboardFunc(Key);
 196    glutDisplayFunc(Redisplay);
 197    ParseOptions(argc, argv);
 198    Init();
 199    glutMainLoop();
 200    return 0;
 201 }