summaryrefslogtreecommitdiff
path: root/tests/OffscreenContext.mm
blob: 5a6a8ec7c15c2b1af196a80f7e4c418a6704aa6b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
#include "OffscreenContext.h"
#include "imageutils.h"
#include "fbo.h"

#import <AppKit/AppKit.h>   // for NSOpenGL...


#define REPORTGLERROR(task) { GLenum tGLErr = glGetError(); if (tGLErr != GL_NO_ERROR) { std::cout << "OpenGL error " << tGLErr << " while " << task << "\n"; } }

struct OffscreenContext
{
  NSOpenGLContext *openGLContext;
  NSAutoreleasePool *pool;
  int width;
  int height;
  fbo_t *fbo;
};

string offscreen_context_getinfo(OffscreenContext *ctx)
{
  stringstream out;
  out << "GL context creator: Cocoa / CGL\n"
      << "PNG generator: Core Foundation\n"
      << "OS info: Mac OSX\n"
      << "Machine: Apple(TM) Mac(TM)\n";
  return out.str();
}

OffscreenContext *create_offscreen_context(int w, int h)
{
  OffscreenContext *ctx = new OffscreenContext;
  ctx->width = w;
  ctx->height = h;

  ctx->pool = [NSAutoreleasePool new];

  // Create an OpenGL context just so that OpenGL calls will work. 
  // Will not be used for actual rendering.
                                   
  NSOpenGLPixelFormatAttribute attributes[] = {
    NSOpenGLPFAPixelBuffer,
    NSOpenGLPFANoRecovery,
    NSOpenGLPFAAccelerated,
    NSOpenGLPFADepthSize, 24,
    NSOpenGLPFAStencilSize, 8,
    (NSOpenGLPixelFormatAttribute) 0
  };
  NSOpenGLPixelFormat *pixFormat = [[[NSOpenGLPixelFormat alloc] initWithAttributes:attributes] autorelease];

  // Create and make current the OpenGL context to render with (with color and depth buffers)
  ctx->openGLContext = [[NSOpenGLContext alloc] initWithFormat:pixFormat shareContext:nil];
  if (!ctx->openGLContext) {
    std::cerr << "Unable to create NSOpenGLContext\n";
    return NULL;
  }

  [ctx->openGLContext makeCurrentContext];
  
  glewInit();
#ifdef DEBUG
  std::cout << "GLEW version " << glewGetString(GLEW_VERSION) << "\n";
  std::cout << (const char *)glGetString(GL_RENDERER) << "(" << (const char *)glGetString(GL_VENDOR) << ")\n"
       << "OpenGL version " << (const char *)glGetString(GL_VERSION) << "\n";
  std::cout  << "Extensions: " << (const char *)glGetString(GL_EXTENSIONS) << "\n";
  
  
  if (GLEW_ARB_framebuffer_object) {
    std::cout << "ARB_FBO supported\n";
  }
  if (GLEW_EXT_framebuffer_object) {
    std::cout << "EXT_FBO supported\n";
  }
  if (GLEW_EXT_packed_depth_stencil) {
    std::cout << "EXT_packed_depth_stencil\n";
  }
#endif

  ctx->fbo = fbo_new();
  if (!fbo_init(ctx->fbo, w, h)) {
    return NULL;
  }

  return ctx;
}

bool teardown_offscreen_context(OffscreenContext *ctx)
{
  fbo_unbind(ctx->fbo);
  fbo_delete(ctx->fbo);

  /*
   * Cleanup
   */
  [ctx->openGLContext clearDrawable];
  [ctx->openGLContext release];

  [ctx->pool release];
  return true;
}

/*!
  Capture framebuffer from OpenGL and write it to the given filename as PNG.
*/
bool save_framebuffer(OffscreenContext *ctx, const char *filename)
{
  if (!ctx || !filename) return false;
  // Read pixels from OpenGL
  int samplesPerPixel = 4; // R, G, B and A
  int rowBytes = samplesPerPixel * ctx->width;
  unsigned char *bufferData = (unsigned char *)malloc(rowBytes * ctx->height);
  if (!bufferData) {
    std::cerr << "Unable to allocate buffer for image extraction.";
    return 1;
  }
  glReadPixels(0, 0, ctx->width, ctx->height, GL_RGBA, GL_UNSIGNED_BYTE, 
               bufferData);
  REPORTGLERROR("reading pixels from framebuffer");
  
  // Flip it vertically - images read from OpenGL buffers are upside-down
  unsigned char *flippedBuffer = (unsigned char *)malloc(rowBytes * ctx->height);
  if (!flippedBuffer) {
    std::cout << "Unable to allocate flipped buffer for corrected image.";
    return 1;
  }
  flip_image(bufferData, flippedBuffer, samplesPerPixel, ctx->width, ctx->height);

  bool writeok = write_png(filename, flippedBuffer, ctx->width, ctx->height);

  free(flippedBuffer);
  free(bufferData);

  return writeok;
}

void bind_offscreen_context(OffscreenContext *ctx)
{
  fbo_bind(ctx->fbo);
}
contact: Jan Huwald // Impressum