src/trivial/drawarrays.c

   1 /* Basic VBO */
   2
   3 #include <assert.h>
   4 #include <string.h>
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <math.h>
   8 #include <glad/glad.h>
   9 #include "glut_wrap.h"
  10
  11
  12 struct {
  13    GLfloat pos[3];
  14    GLubyte color[4];
  15 } verts[] =
  16 {
  17    { {  0.9, -0.9, 0.0 },
  18      { 0x00, 0x00, 0xff, 0x00 }
  19    },
  20
  21    { {  0.9,  0.9, 0.0 },
  22      { 0x00, 0xff, 0x00, 0x00 }
  23    },
  24
  25    { { -0.9,  0.9, 0.0 },
  26      { 0xff, 0x00, 0x00, 0x00 }
  27    },
  28
  29    { { -0.9, -0.9, 0.0 },
  30      { 0xff, 0xff, 0xff, 0x00 }
  31    },
  32 };
  33
  34 static void Init( void )
  35 {
  36    GLint errnum;
  37    GLuint prognum;
  38
  39    static const char *prog1 =
  40       "!!ARBvp1.0\n"
  41       "MOV  result.color, vertex.color;\n"
  42       "MOV  result.position, vertex.position;\n"
  43       "END\n";
  44
  45    glGenProgramsARB(1, &prognum);
  46    glBindProgramARB(GL_VERTEX_PROGRAM_ARB, prognum);
  47    glProgramStringARB(GL_VERTEX_PROGRAM_ARB, GL_PROGRAM_FORMAT_ASCII_ARB,
  48                       strlen(prog1), (const GLubyte *) prog1);
  49
  50    assert(glIsProgramARB(prognum));
  51    errnum = glGetError();
  52    printf("glGetError = %d\n", errnum);
  53    if (errnum != GL_NO_ERROR)
  54    {
  55       GLint errorpos;
  56
  57       glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &errorpos);
  58       printf("errorpos: %d\n", errorpos);
  59       printf("%s\n", (char *)glGetString(GL_PROGRAM_ERROR_STRING_ARB));
  60    }
  61
  62
  63    glEnableClientState( GL_VERTEX_ARRAY );
  64    glEnableClientState( GL_COLOR_ARRAY );
  65
  66    glVertexPointer( 3, GL_FLOAT, sizeof(verts[0]), verts[0].pos );
  67    glColorPointer( 4, GL_UNSIGNED_BYTE, sizeof(verts[0]), verts[0].color );
  68
  69 }
  70
  71
  72
  73 static void Display( void )
  74 {
  75    glClearColor(0.3, 0.3, 0.3, 1);
  76    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
  77
  78    glEnable(GL_VERTEX_PROGRAM_ARB);
  79
  80    /* glDrawArrays( GL_TRIANGLES, 0, 3 ); */
  81    glDrawArrays( GL_TRIANGLES, 1, 3 );
  82
  83    glFlush();
  84 }
  85
  86
  87 static void Reshape( int width, int height )
  88 {
  89    glViewport( 0, 0, width, height );
  90    glMatrixMode( GL_PROJECTION );
  91    glLoadIdentity();
  92    glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0);
  93    glMatrixMode( GL_MODELVIEW );
  94    glLoadIdentity();
  95    /*glTranslatef( 0.0, 0.0, -15.0 );*/
  96 }
  97
  98
  99 static void Key( unsigned char key, int x, int y )
 100 {
 101    (void) x;
 102    (void) y;
 103    switch (key) {
 104       case 27:
 105          exit(0);
 106          break;
 107    }
 108    glutPostRedisplay();
 109 }
 110
 111
 112
 113
 114 int main( int argc, char *argv[] )
 115 {
 116    glutInit( &argc, argv );
 117    glutInitWindowPosition( 0, 0 );
 118    glutInitWindowSize( 250, 250 );
 119    glutInitDisplayMode( GLUT_RGB | GLUT_SINGLE | GLUT_DEPTH );
 120    glutCreateWindow(argv[0]);
 121    gladLoadGL();
 122    glutReshapeFunc( Reshape );
 123    glutKeyboardFunc( Key );
 124    glutDisplayFunc( Display );
 125    Init();
 126    glutMainLoop();
 127    return 0;
 128 }