1 files changed, 113 insertions, 0 deletions
diff --git a/libdimension/canvas/gl.c b/libdimension/canvas/gl.c
new file mode 100644
index 0000000..900f53c
--- /dev/null
+++ b/libdimension/canvas/gl.c
@@ -0,0 +1,113 @@
+/*************************************************************************
+ * Copyright (C) 2009-2014 Tavian Barnes <tavianator@tavianator.com>     *
+ *                                                                       *
+ * This file is part of The Dimension Library.                           *
+ *                                                                       *
+ * The Dimension Library is free software; you can redistribute it and/  *
+ * or modify it under the terms of the GNU Lesser General Public License *
+ * as published by the Free Software Foundation; either version 3 of the *
+ * License, or (at your option) any later version.                       *
+ *                                                                       *
+ * The Dimension Library is distributed in the hope that it will be      *
+ * useful, but WITHOUT ANY WARRANTY; without even the implied warranty   *
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU  *
+ * Lesser General Public License for more details.                       *
+ *                                                                       *
+ * You should have received a copy of the GNU Lesser General Public      *
+ * License along with this program.  If not, see                         *
+ * <http://www.gnu.org/licenses/>.                                       *
+ *************************************************************************/
+
+/**
+ * @file
+ * OpenGL import/export.
+ */
+
+#include "internal/rgba.h"
+#include "dimension/canvas.h"
+#include <GL/gl.h>
+#include <math.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+// Optimize canvas for GL drawing
+int
+dmnsn_gl_optimize_canvas(dmnsn_pool *pool, dmnsn_canvas *canvas)
+{
+  dmnsn_rgba8_optimize_canvas(pool, canvas);
+  return 0;
+}
+
+// Write canvas to GL framebuffer.  Returns 0 on success, nonzero on failure
+int
+dmnsn_gl_write_canvas(const dmnsn_canvas *canvas)
+{
+  size_t width = canvas->width;
+  size_t height = canvas->height;
+
+  // Check if we can optimize this
+  dmnsn_rgba8_optimizer *rgba8 = (dmnsn_rgba8_optimizer *)dmnsn_canvas_find_optimizer(canvas, dmnsn_rgba8_optimizer_fn);
+  if (rgba8) {
+    glDrawPixels(width, height, GL_RGBA, GL_UNSIGNED_BYTE, rgba8->data);
+    return glGetError() == GL_NO_ERROR ? 0 : 1;
+  }
+
+  // We couldn't, so transform the canvas to RGB now
+  GLubyte *pixels = dmnsn_malloc(4*width*height*sizeof(GLubyte));
+
+  for (size_t y = 0; y < height; ++y) {
+    for (size_t x = 0; x < width; ++x) {
+      GLubyte *pixel = pixels + 4*(y*width + x);
+
+      dmnsn_tcolor tcolor = dmnsn_canvas_get_pixel(canvas, x, y);
+      tcolor = dmnsn_tcolor_remove_filter(tcolor);
+      tcolor.c = dmnsn_color_to_sRGB(tcolor.c);
+      tcolor = dmnsn_tcolor_clamp(tcolor);
+
+      pixel[0] = lround(tcolor.c.R*UINT8_MAX);
+      pixel[1] = lround(tcolor.c.G*UINT8_MAX);
+      pixel[2] = lround(tcolor.c.B*UINT8_MAX);
+      pixel[3] = lround(tcolor.T*UINT8_MAX);
+    }
+  }
+
+  glDrawPixels(width, height, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
+
+  dmnsn_free(pixels);
+  return glGetError() == GL_NO_ERROR ? 0 : 1;
+}
+
+// Read a canvas from a GL framebuffer.  Returns NULL on failure.
+int
+dmnsn_gl_read_canvas(dmnsn_canvas *canvas, size_t x0, size_t y0)
+{
+  size_t width = canvas->width;
+  size_t height = canvas->height;
+
+  // Array of 16-bit ints in RGBA order
+  GLushort *pixels = dmnsn_malloc(4*width*height*sizeof(GLushort));
+  glReadPixels(x0, y0, width, height, GL_RGBA, GL_UNSIGNED_SHORT, pixels);
+  if (glGetError() != GL_NO_ERROR) {
+    dmnsn_free(pixels);
+    return -1;
+  }
+
+  for (size_t y = 0; y < height; ++y) {
+    for (size_t x = 0; x < width; ++x) {
+      GLushort *pixel = pixels + 4*(y*width + x);
+
+      dmnsn_tcolor tcolor = dmnsn_new_tcolor5(
+        (double)pixel[0]/UINT16_MAX,
+        (double)pixel[1]/UINT16_MAX,
+        (double)pixel[2]/UINT16_MAX,
+        (double)pixel[3]/UINT16_MAX,
+        0.0
+      );
+      tcolor.c = dmnsn_color_from_sRGB(tcolor.c);
+      dmnsn_canvas_set_pixel(canvas, x, y, tcolor);
+    }
+  }
+
+  dmnsn_free(pixels);
+  return 0;
+}