glfw/src/gamma.c
2011-09-20 15:44:54 +02:00

117 lines
3.5 KiB
C

//========================================================================
// GLFW - An OpenGL library
// Platform: Any
// API version: 3.0
// WWW: http://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 <string.h>
//////////////////////////////////////////////////////////////////////////
////// GLFW public API //////
//////////////////////////////////////////////////////////////////////////
//========================================================================
// Calculate a gamma ramp from the specified value and set it
//========================================================================
GLFWAPI void glfwSetGamma(float gamma)
{
int i, size = GLFW_GAMMA_RAMP_SIZE;
GLFWgammaramp ramp;
if (!_glfwInitialized)
{
_glfwSetError(GLFW_NOT_INITIALIZED, NULL);
return;
}
if (gamma <= 0.f)
{
_glfwSetError(GLFW_INVALID_VALUE,
"glfwSetGamma: Gamma value must be greater than zero");
return;
}
for (i = 0; i < size; i++)
{
float value = (float) i / ((float) (size - 1));
// Apply gamma
value = (float) pow(value, 1.f / gamma) * 65535.f + 0.5f;
// Clamp values
if (value < 0.f)
value = 0.f;
else if (value > 65535.f)
value = 65535.f;
// Set the gamma ramp values
ramp.red[i] = (unsigned short) value;
ramp.green[i] = (unsigned short) value;
ramp.blue[i] = (unsigned short) value;
}
glfwSetGammaRamp(&ramp);
}
//========================================================================
// Return the cached currently set gamma ramp
//========================================================================
GLFWAPI void glfwGetGammaRamp(GLFWgammaramp* ramp)
{
if (!_glfwInitialized)
{
_glfwSetError(GLFW_NOT_INITIALIZED, NULL);
return;
}
*ramp = _glfwLibrary.currentRamp;
}
//========================================================================
// Make the specified gamma ramp current
//========================================================================
GLFWAPI void glfwSetGammaRamp(const GLFWgammaramp* ramp)
{
if (!_glfwInitialized)
{
_glfwSetError(GLFW_NOT_INITIALIZED, NULL);
return;
}
_glfwPlatformSetGammaRamp(ramp);
_glfwLibrary.currentRamp = *ramp;
}