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glfw/src/gamma.c
2014-03-06 21:05:55 +01:00

123 lines
3.5 KiB
C

//========================================================================
// GLFW 3.1 - www.glfw.org
//------------------------------------------------------------------------
// Copyright (c) 2010 Camilla Berglund <elmindreda@elmindreda.org>
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software. If you use this software
// in a product, an acknowledgment in the product documentation would
// be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not
// be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
// distribution.
//
//========================================================================
#include "internal.h"
#include <math.h>
#include <stdlib.h>
#include <string.h>
//////////////////////////////////////////////////////////////////////////
////// GLFW internal API //////
//////////////////////////////////////////////////////////////////////////
void _glfwAllocGammaArrays(GLFWgammaramp* ramp, unsigned int size)
{
ramp->red = calloc(size, sizeof(unsigned short));
ramp->green = calloc(size, sizeof(unsigned short));
ramp->blue = calloc(size, sizeof(unsigned short));
ramp->size = size;
}
void _glfwFreeGammaArrays(GLFWgammaramp* ramp)
{
free(ramp->red);
free(ramp->green);
free(ramp->blue);
memset(ramp, 0, sizeof(GLFWgammaramp));
}
//////////////////////////////////////////////////////////////////////////
////// GLFW public API //////
//////////////////////////////////////////////////////////////////////////
GLFWAPI void glfwSetGamma(GLFWmonitor* handle, float gamma)
{
int i;
unsigned short values[256];
GLFWgammaramp ramp;
_GLFW_REQUIRE_INIT();
if (gamma <= 0.f)
{
_glfwInputError(GLFW_INVALID_VALUE,
"Gamma value must be greater than zero");
return;
}
for (i = 0; i < 256; i++)
{
double value;
// Calculate intensity
value = i / 255.0;
// Apply gamma curve
value = pow(value, 1.0 / gamma) * 65535.0 + 0.5;
// Clamp to value range
if (value > 65535.0)
value = 65535.0;
values[i] = (unsigned short) value;
}
ramp.red = values;
ramp.green = values;
ramp.blue = values;
ramp.size = 256;
glfwSetGammaRamp(handle, &ramp);
}
GLFWAPI const GLFWgammaramp* glfwGetGammaRamp(GLFWmonitor* handle)
{
_GLFWmonitor* monitor = (_GLFWmonitor*) handle;
_GLFW_REQUIRE_INIT_OR_RETURN(NULL);
_glfwFreeGammaArrays(&monitor->currentRamp);
_glfwPlatformGetGammaRamp(monitor, &monitor->currentRamp);
return &monitor->currentRamp;
}
GLFWAPI void glfwSetGammaRamp(GLFWmonitor* handle, const GLFWgammaramp* ramp)
{
_GLFWmonitor* monitor = (_GLFWmonitor*) handle;
_GLFW_REQUIRE_INIT();
if (!monitor->originalRamp.size)
_glfwPlatformGetGammaRamp(monitor, &monitor->originalRamp);
_glfwPlatformSetGammaRamp(monitor, ramp);
}