Provide interface to export canvas to openGL.

1 files changed, 91 insertions, 0 deletions

diff --git a/libdimension/gl.c b/libdimension/gl.c
new file mode 100644
index 0000000..3542a2d
--- /dev/null
+++ b/libdimension/gl.c
@@ -0,0 +1,91 @@
+/*************************************************************************
+ * Copyright (C) 2008 Tavian Barnes <tavianator@gmail.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/>.                                       *
+ *************************************************************************/
+
+#include "dimension.h"
+#include <GL/gl.h>
+
+/* Write canvas to GL framebuffer.  Returns 0 on success, nonzero on failure */
+int
+dmnsn_gl_write_canvas(const dmnsn_canvas *canvas)
+{
+  GLuint *pixels; /* Array of 32-bit ints in RGBA order */
+  GLuint *pixel;
+  dmnsn_sRGB sRGB;
+  dmnsn_color color;
+  unsigned int x, y, width, height;
+
+  width = canvas->x;
+  height = canvas->y;
+
+  pixels = malloc(4*width*height*sizeof(GLuint));
+  if (!pixels) {
+    return 1;
+  }
+
+  for (y = 0; y < height; ++y) {
+    for (x = 0; x < width; ++x) {
+      pixel = pixels + 4*(y*width + x);
+
+      color = dmnsn_get_pixel(canvas, x, y);
+      sRGB = dmnsn_sRGB_from_color(color);
+
+      /* Saturate R, G, and B to [0, UINT32_MAX] */
+
+      if (sRGB.R <= 0.0) {
+        pixel[0] = 0;
+      } else if (sRGB.R >= 1.0) {
+        pixel[0] = UINT32_MAX;
+      } else {
+        pixel[0] = sRGB.R*UINT32_MAX;
+      }
+
+      if (sRGB.G <= 0.0) {
+        pixel[1] = 0;
+      } else if (sRGB.G >= 1.0) {
+        pixel[1] = UINT32_MAX;
+      } else {
+        pixel[1] = sRGB.G*UINT32_MAX;
+      }
+
+      if (sRGB.B <= 0.0) {
+        pixel[2] = 0;
+      } else if (sRGB.B >= 1.0) {
+        pixel[2] = UINT32_MAX;
+      } else {
+        pixel[2] = sRGB.B*UINT32_MAX;
+      }
+
+      /* color.filter + color.trans is in [0.0, 1.0] by definition */
+      pixel[3] = (color.filter + color.trans)*UINT32_MAX;
+    }
+  }
+
+  glDrawPixels(width, height, GL_RGBA, GL_UNSIGNED_INT, pixels);
+
+  free(pixels);
+  return 0;
+}
+
+/* Read a canvas from a GL framebuffer.  Returns NULL on failure. */
+dmnsn_canvas *
+dmnsn_gl_read_canvas()
+{
+  return NULL;
+}