Moved OpenGL related function to opengl.c, minor formatting.
diff --git a/src/opengl.c b/src/opengl.c
index df8b3ee..68aad2a 100644
--- a/src/opengl.c
+++ b/src/opengl.c
@@ -31,6 +31,7 @@
#include "internal.h"
#include <string.h>
+#include <limits.h>
//////////////////////////////////////////////////////////////////////////
@@ -38,6 +39,163 @@
//////////////////////////////////////////////////////////////////////////
//========================================================================
+// Return the available framebuffer config closest to the desired values
+// This is based on the manual GLX Visual selection from 2.6
+//========================================================================
+
+const _GLFWfbconfig* _glfwChooseFBConfig(const _GLFWfbconfig* desired,
+ const _GLFWfbconfig* alternatives,
+ unsigned int count)
+{
+ unsigned int i;
+ unsigned int missing, leastMissing = UINT_MAX;
+ unsigned int colorDiff, leastColorDiff = UINT_MAX;
+ unsigned int extraDiff, leastExtraDiff = UINT_MAX;
+ const _GLFWfbconfig* current;
+ const _GLFWfbconfig* closest = NULL;
+
+ for (i = 0; i < count; i++)
+ {
+ current = alternatives + i;
+
+ if (desired->stereo > 0 && current->stereo == 0)
+ {
+ // Stereo is a hard constraint
+ continue;
+ }
+
+ // Count number of missing buffers
+ {
+ missing = 0;
+
+ if (desired->alphaBits > 0 && current->alphaBits == 0)
+ missing++;
+
+ if (desired->depthBits > 0 && current->depthBits == 0)
+ missing++;
+
+ if (desired->stencilBits > 0 && current->stencilBits == 0)
+ missing++;
+
+ if (desired->auxBuffers > 0 && current->auxBuffers < desired->auxBuffers)
+ missing += desired->auxBuffers - current->auxBuffers;
+
+ if (desired->samples > 0 && current->samples == 0)
+ {
+ // Technically, several multisampling buffers could be
+ // involved, but that's a lower level implementation detail and
+ // not important to us here, so we count them as one
+ missing++;
+ }
+ }
+
+ // These polynomials make many small channel size differences matter
+ // less than one large channel size difference
+
+ // Calculate color channel size difference value
+ {
+ colorDiff = 0;
+
+ if (desired->redBits > 0)
+ {
+ colorDiff += (desired->redBits - current->redBits) *
+ (desired->redBits - current->redBits);
+ }
+
+ if (desired->greenBits > 0)
+ {
+ colorDiff += (desired->greenBits - current->greenBits) *
+ (desired->greenBits - current->greenBits);
+ }
+
+ if (desired->blueBits > 0)
+ {
+ colorDiff += (desired->blueBits - current->blueBits) *
+ (desired->blueBits - current->blueBits);
+ }
+ }
+
+ // Calculate non-color channel size difference value
+ {
+ extraDiff = 0;
+
+ if (desired->alphaBits > 0)
+ {
+ extraDiff += (desired->alphaBits - current->alphaBits) *
+ (desired->alphaBits - current->alphaBits);
+ }
+
+ if (desired->depthBits > 0)
+ {
+ extraDiff += (desired->depthBits - current->depthBits) *
+ (desired->depthBits - current->depthBits);
+ }
+
+ if (desired->stencilBits > 0)
+ {
+ extraDiff += (desired->stencilBits - current->stencilBits) *
+ (desired->stencilBits - current->stencilBits);
+ }
+
+ if (desired->accumRedBits > 0)
+ {
+ extraDiff += (desired->accumRedBits - current->accumRedBits) *
+ (desired->accumRedBits - current->accumRedBits);
+ }
+
+ if (desired->accumGreenBits > 0)
+ {
+ extraDiff += (desired->accumGreenBits - current->accumGreenBits) *
+ (desired->accumGreenBits - current->accumGreenBits);
+ }
+
+ if (desired->accumBlueBits > 0)
+ {
+ extraDiff += (desired->accumBlueBits - current->accumBlueBits) *
+ (desired->accumBlueBits - current->accumBlueBits);
+ }
+
+ if (desired->accumAlphaBits > 0)
+ {
+ extraDiff += (desired->accumAlphaBits - current->accumAlphaBits) *
+ (desired->accumAlphaBits - current->accumAlphaBits);
+ }
+
+ if (desired->samples > 0)
+ {
+ extraDiff += (desired->samples - current->samples) *
+ (desired->samples - current->samples);
+ }
+ }
+
+ // Figure out if the current one is better than the best one found so far
+ // Least number of missing buffers is the most important heuristic,
+ // then color buffer size match and lastly size match for other buffers
+
+ if (missing < leastMissing)
+ closest = current;
+ else if (missing == leastMissing)
+ {
+ if ((colorDiff < leastColorDiff) ||
+ (colorDiff == leastColorDiff && extraDiff < leastExtraDiff))
+ {
+ closest = current;
+ }
+ }
+
+ if (current == closest)
+ {
+ leastMissing = missing;
+ leastColorDiff = colorDiff;
+ leastExtraDiff = extraDiff;
+ }
+ }
+
+ return closest;
+}
+
+
+//========================================================================
// Parses the OpenGL version string and extracts the version number
//========================================================================
