+ return GL_TRUE;
+ }
+
+ /* not handled */
+ return GL_FALSE;
+}
+
+
+/**
+ * When we're using a low-precision color buffer (like 16-bit 5/6/5)
+ * we have to adjust our color values a bit to pass conformance.
+ * The problem is when a 5 or 6-bit color value is convert to an 8-bit
+ * value and then a floating point value, the floating point values don't
+ * increment uniformly as the 5 or 6-bit value is incremented.
+ *
+ * This function adjusts floating point values to compensate.
+ */
+static void
+adjust_colors(GLcontext *ctx, GLuint n, GLfloat rgba[][4])
+{
+ const GLuint rShift = 8 - ctx->Visual.redBits;
+ const GLuint gShift = 8 - ctx->Visual.greenBits;
+ const GLuint bShift = 8 - ctx->Visual.blueBits;
+ const GLfloat rScale = 1.0F / (GLfloat) ((1 << ctx->Visual.redBits ) - 1);
+ const GLfloat gScale = 1.0F / (GLfloat) ((1 << ctx->Visual.greenBits) - 1);
+ const GLfloat bScale = 1.0F / (GLfloat) ((1 << ctx->Visual.blueBits ) - 1);
+ GLuint i;
+ for (i = 0; i < n; i++) {
+ GLint r, g, b;
+ /* convert float back to ubyte */
+ CLAMPED_FLOAT_TO_UBYTE(r, rgba[i][RCOMP]);
+ CLAMPED_FLOAT_TO_UBYTE(g, rgba[i][GCOMP]);
+ CLAMPED_FLOAT_TO_UBYTE(b, rgba[i][BCOMP]);
+ /* using only the N most significant bits of the ubyte value, convert to
+ * float in [0,1].
+ */
+ rgba[i][RCOMP] = (GLfloat) (r >> rShift) * rScale;
+ rgba[i][GCOMP] = (GLfloat) (g >> gShift) * gScale;
+ rgba[i][BCOMP] = (GLfloat) (b >> bShift) * bScale;