shithub: cstory

Download patch

ref: 7e926451def20e69909b199adba48e7dceee608d
parent: fc102cd5a5e3dde21fab24b0590f30327be03f26
author: Clownacy <Clownacy@users.noreply.github.com>
date: Wed Aug 7 22:59:02 EDT 2019 

Optimise the gamma-correction

I should probably create a Common.cpp file or something


--- a/src/Backends/Rendering/OpenGL3.cpp
+++ b/src/Backends/Rendering/OpenGL3.cpp
@@ -1,6 +1,5 @@
 #include "../Rendering.h"
 
-#include <math.h>
 #include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -205,6 +204,36 @@
 	return program_id;
 }
 
+static unsigned char GammaCorrect(unsigned char value)
+{
+	/*
+		Generated with...
+		for (unsigned int i = 0; i < 0x100; ++i)
+			lookup[i] = pow(i / 255.0, 1.0 / 1.8) * 255.0;
+	*/
+
+	const unsigned char lookup[0x100] = {
+		0x00, 0x0B, 0x11, 0x15, 0x19, 0x1C, 0x1F, 0x22, 0x25, 0x27, 0x2A, 0x2C, 0x2E, 0x30, 0x32, 0x34,
+		0x36, 0x38, 0x3A, 0x3C, 0x3D, 0x3F, 0x41, 0x43, 0x44, 0x46, 0x47, 0x49, 0x4A, 0x4C, 0x4D, 0x4F,
+		0x50, 0x51, 0x53, 0x54, 0x55, 0x57, 0x58, 0x59, 0x5B, 0x5C, 0x5D, 0x5E, 0x60, 0x61, 0x62, 0x63,
+		0x64, 0x65, 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75,
+		0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C, 0x7D, 0x7E, 0x7F, 0x80, 0x81, 0x82, 0x83, 0x84, 0x84,
+		0x85, 0x86, 0x87, 0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8E, 0x8F, 0x90, 0x91, 0x92, 0x93,
+		0x94, 0x95, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0x9A, 0x9B, 0x9C, 0x9D, 0x9E, 0x9F, 0x9F, 0xA0,
+		0xA1, 0xA2, 0xA3, 0xA3, 0xA4, 0xA5, 0xA6, 0xA6, 0xA7, 0xA8, 0xA9, 0xAA, 0xAA, 0xAB, 0xAC, 0xAD,
+		0xAD, 0xAE, 0xAF, 0xB0, 0xB0, 0xB1, 0xB2, 0xB3, 0xB3, 0xB4, 0xB5, 0xB6, 0xB6, 0xB7, 0xB8, 0xB8,
+		0xB9, 0xBA, 0xBB, 0xBB, 0xBC, 0xBD, 0xBD, 0xBE, 0xBF, 0xBF, 0xC0, 0xC1, 0xC2, 0xC2, 0xC3, 0xC4,
+		0xC4, 0xC5, 0xC6, 0xC6, 0xC7, 0xC8, 0xC8, 0xC9, 0xCA, 0xCA, 0xCB, 0xCC, 0xCC, 0xCD, 0xCE, 0xCE,
+		0xCF, 0xD0, 0xD0, 0xD1, 0xD2, 0xD2, 0xD3, 0xD4, 0xD4, 0xD5, 0xD6, 0xD6, 0xD7, 0xD7, 0xD8, 0xD9,
+		0xD9, 0xDA, 0xDB, 0xDB, 0xDC, 0xDC, 0xDD, 0xDE, 0xDE, 0xDF, 0xE0, 0xE0, 0xE1, 0xE1, 0xE2, 0xE3,
+		0xE3, 0xE4, 0xE4, 0xE5, 0xE6, 0xE6, 0xE7, 0xE7, 0xE8, 0xE9, 0xE9, 0xEA, 0xEA, 0xEB, 0xEC, 0xEC,
+		0xED, 0xED, 0xEE, 0xEF, 0xEF, 0xF0, 0xF0, 0xF1, 0xF1, 0xF2, 0xF3, 0xF3, 0xF4, 0xF4, 0xF5, 0xF5,
+		0xF6, 0xF7, 0xF7, 0xF8, 0xF8, 0xF9, 0xF9, 0xFA, 0xFB, 0xFB, 0xFC, 0xFC, 0xFD, 0xFD, 0xFE, 0xFF
+	}
+
+	return lookup[value];
+}
+
 SDL_Window* Backend_CreateWindow(const char *title, int width, int height)
 {
 	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
@@ -555,7 +584,7 @@
 				{
 					for (unsigned int i = 0; i < 3; ++i)
 					{
-						*destination_pointer++ = (unsigned char)(pow((*source_pointer++ / 255.0), 1.0 / 1.8) * 255.0);
+						*destination_pointer++ = GammaCorrect(*source_pointer++);
 					}
 				}
 			}
@@ -570,7 +599,7 @@
 
 				for (unsigned int x = 0; x < width; ++x)
 				{
-					*destination_pointer++ = (unsigned char)(pow((double)*source_pointer++ / (total_greys - 1), 1.0 / 1.8) * 255.0);
+					*destination_pointer++ = GammaCorrect((*source_pointer++ * 0xFF) / (total_greys - 1));
 				}
 			}
 
--- a/src/Backends/Rendering/SDLSurface.cpp
+++ b/src/Backends/Rendering/SDLSurface.cpp
@@ -1,6 +1,5 @@
 #include "../Rendering.h"
 
-#include <math.h>
 #include <stddef.h>
 #include <stdlib.h>
 
@@ -39,6 +38,36 @@
 		sdl_rect->h = 0;
 }
 
+static unsigned char GammaCorrect(unsigned char value)
+{
+	/*
+		Generated with...
+		for (unsigned int i = 0; i < 0x100; ++i)
+			lookup[i] = pow(i / 255.0, 1.0 / 1.8) * 255.0;
+	*/
+
+	const unsigned char lookup[0x100] = {
+		0x00, 0x0B, 0x11, 0x15, 0x19, 0x1C, 0x1F, 0x22, 0x25, 0x27, 0x2A, 0x2C, 0x2E, 0x30, 0x32, 0x34,
+		0x36, 0x38, 0x3A, 0x3C, 0x3D, 0x3F, 0x41, 0x43, 0x44, 0x46, 0x47, 0x49, 0x4A, 0x4C, 0x4D, 0x4F,
+		0x50, 0x51, 0x53, 0x54, 0x55, 0x57, 0x58, 0x59, 0x5B, 0x5C, 0x5D, 0x5E, 0x60, 0x61, 0x62, 0x63,
+		0x64, 0x65, 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75,
+		0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C, 0x7D, 0x7E, 0x7F, 0x80, 0x81, 0x82, 0x83, 0x84, 0x84,
+		0x85, 0x86, 0x87, 0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8E, 0x8F, 0x90, 0x91, 0x92, 0x93,
+		0x94, 0x95, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0x9A, 0x9B, 0x9C, 0x9D, 0x9E, 0x9F, 0x9F, 0xA0,
+		0xA1, 0xA2, 0xA3, 0xA3, 0xA4, 0xA5, 0xA6, 0xA6, 0xA7, 0xA8, 0xA9, 0xAA, 0xAA, 0xAB, 0xAC, 0xAD,
+		0xAD, 0xAE, 0xAF, 0xB0, 0xB0, 0xB1, 0xB2, 0xB3, 0xB3, 0xB4, 0xB5, 0xB6, 0xB6, 0xB7, 0xB8, 0xB8,
+		0xB9, 0xBA, 0xBB, 0xBB, 0xBC, 0xBD, 0xBD, 0xBE, 0xBF, 0xBF, 0xC0, 0xC1, 0xC2, 0xC2, 0xC3, 0xC4,
+		0xC4, 0xC5, 0xC6, 0xC6, 0xC7, 0xC8, 0xC8, 0xC9, 0xCA, 0xCA, 0xCB, 0xCC, 0xCC, 0xCD, 0xCE, 0xCE,
+		0xCF, 0xD0, 0xD0, 0xD1, 0xD2, 0xD2, 0xD3, 0xD4, 0xD4, 0xD5, 0xD6, 0xD6, 0xD7, 0xD7, 0xD8, 0xD9,
+		0xD9, 0xDA, 0xDB, 0xDB, 0xDC, 0xDC, 0xDD, 0xDE, 0xDE, 0xDF, 0xE0, 0xE0, 0xE1, 0xE1, 0xE2, 0xE3,
+		0xE3, 0xE4, 0xE4, 0xE5, 0xE6, 0xE6, 0xE7, 0xE7, 0xE8, 0xE9, 0xE9, 0xEA, 0xEA, 0xEB, 0xEC, 0xEC,
+		0xED, 0xED, 0xEE, 0xEF, 0xEF, 0xF0, 0xF0, 0xF1, 0xF1, 0xF2, 0xF3, 0xF3, 0xF4, 0xF4, 0xF5, 0xF5,
+		0xF6, 0xF7, 0xF7, 0xF8, 0xF8, 0xF9, 0xF9, 0xFA, 0xFB, 0xFB, 0xFC, 0xFC, 0xFD, 0xFD, 0xFE, 0xFF
+	}
+
+	return lookup[value];
+}
+
 SDL_Window* Backend_CreateWindow(const char *title, int width, int height)
 {
 	return SDL_CreateWindow(title, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, width, height, 0);
@@ -190,7 +219,7 @@
 					*destination_pointer++ = 0xFF;
 					*destination_pointer++ = 0xFF;
 					*destination_pointer++ = 0xFF;
-					*destination_pointer++ = (unsigned char)(pow((double)*source_pointer++ / (total_greys - 1), 1.0 / 1.8) * 255.0);
+					*destination_pointer++ = GammaCorrect((*source_pointer++ * 0xFF) / (total_greys - 1));
 				}
 			}
 
--- a/src/Backends/Rendering/SDLTexture.cpp
+++ b/src/Backends/Rendering/SDLTexture.cpp
@@ -1,6 +1,5 @@
 #include "../Rendering.h"
 
-#include <math.h>
 #include <stddef.h>
 #include <stdlib.h>
 
@@ -82,6 +81,36 @@
 		sdl_rect->h = 0;
 }
 
+static unsigned char GammaCorrect(unsigned char value)
+{
+	/*
+		Generated with...
+		for (unsigned int i = 0; i < 0x100; ++i)
+			lookup[i] = pow(i / 255.0, 1.0 / 1.8) * 255.0;
+	*/
+
+	const unsigned char lookup[0x100] = {
+		0x00, 0x0B, 0x11, 0x15, 0x19, 0x1C, 0x1F, 0x22, 0x25, 0x27, 0x2A, 0x2C, 0x2E, 0x30, 0x32, 0x34,
+		0x36, 0x38, 0x3A, 0x3C, 0x3D, 0x3F, 0x41, 0x43, 0x44, 0x46, 0x47, 0x49, 0x4A, 0x4C, 0x4D, 0x4F,
+		0x50, 0x51, 0x53, 0x54, 0x55, 0x57, 0x58, 0x59, 0x5B, 0x5C, 0x5D, 0x5E, 0x60, 0x61, 0x62, 0x63,
+		0x64, 0x65, 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75,
+		0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C, 0x7D, 0x7E, 0x7F, 0x80, 0x81, 0x82, 0x83, 0x84, 0x84,
+		0x85, 0x86, 0x87, 0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8E, 0x8F, 0x90, 0x91, 0x92, 0x93,
+		0x94, 0x95, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0x9A, 0x9B, 0x9C, 0x9D, 0x9E, 0x9F, 0x9F, 0xA0,
+		0xA1, 0xA2, 0xA3, 0xA3, 0xA4, 0xA5, 0xA6, 0xA6, 0xA7, 0xA8, 0xA9, 0xAA, 0xAA, 0xAB, 0xAC, 0xAD,
+		0xAD, 0xAE, 0xAF, 0xB0, 0xB0, 0xB1, 0xB2, 0xB3, 0xB3, 0xB4, 0xB5, 0xB6, 0xB6, 0xB7, 0xB8, 0xB8,
+		0xB9, 0xBA, 0xBB, 0xBB, 0xBC, 0xBD, 0xBD, 0xBE, 0xBF, 0xBF, 0xC0, 0xC1, 0xC2, 0xC2, 0xC3, 0xC4,
+		0xC4, 0xC5, 0xC6, 0xC6, 0xC7, 0xC8, 0xC8, 0xC9, 0xCA, 0xCA, 0xCB, 0xCC, 0xCC, 0xCD, 0xCE, 0xCE,
+		0xCF, 0xD0, 0xD0, 0xD1, 0xD2, 0xD2, 0xD3, 0xD4, 0xD4, 0xD5, 0xD6, 0xD6, 0xD7, 0xD7, 0xD8, 0xD9,
+		0xD9, 0xDA, 0xDB, 0xDB, 0xDC, 0xDC, 0xDD, 0xDE, 0xDE, 0xDF, 0xE0, 0xE0, 0xE1, 0xE1, 0xE2, 0xE3,
+		0xE3, 0xE4, 0xE4, 0xE5, 0xE6, 0xE6, 0xE7, 0xE7, 0xE8, 0xE9, 0xE9, 0xEA, 0xEA, 0xEB, 0xEC, 0xEC,
+		0xED, 0xED, 0xEE, 0xEF, 0xEF, 0xF0, 0xF0, 0xF1, 0xF1, 0xF2, 0xF3, 0xF3, 0xF4, 0xF4, 0xF5, 0xF5,
+		0xF6, 0xF7, 0xF7, 0xF8, 0xF8, 0xF9, 0xF9, 0xFA, 0xFB, 0xFB, 0xFC, 0xFC, 0xFD, 0xFD, 0xFE, 0xFF
+	}
+
+	return lookup[value];
+}
+
 SDL_Window* Backend_CreateWindow(const char *title, int width, int height)
 {
 	return SDL_CreateWindow(title, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, width, height, 0);
@@ -352,7 +381,7 @@
 					*destination_pointer++ = 0xFF;
 					*destination_pointer++ = 0xFF;
 					*destination_pointer++ = 0xFF;
-					*destination_pointer++ = (unsigned char)(pow((double)*source_pointer++ / (total_greys - 1), 1.0 / 1.8) * 255.0);
+					*destination_pointer++ = GammaCorrect((*source_pointer++ * 0xFF) / (total_greys - 1));
 				}
 			}
 
--- a/src/Backends/Rendering/Software.cpp
+++ b/src/Backends/Rendering/Software.cpp
@@ -1,6 +1,5 @@
 #include "../Rendering.h"
 
-#include <math.h>
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
@@ -36,6 +35,36 @@
 
 static Backend_Surface framebuffer;
 
+static unsigned char GammaCorrect(unsigned char value)
+{
+	/*
+		Generated with...
+		for (unsigned int i = 0; i < 0x100; ++i)
+			lookup[i] = pow(i / 255.0, 1.0 / 1.8) * 255.0;
+	*/
+
+	const unsigned char lookup[0x100] = {
+		0x00, 0x0B, 0x11, 0x15, 0x19, 0x1C, 0x1F, 0x22, 0x25, 0x27, 0x2A, 0x2C, 0x2E, 0x30, 0x32, 0x34,
+		0x36, 0x38, 0x3A, 0x3C, 0x3D, 0x3F, 0x41, 0x43, 0x44, 0x46, 0x47, 0x49, 0x4A, 0x4C, 0x4D, 0x4F,
+		0x50, 0x51, 0x53, 0x54, 0x55, 0x57, 0x58, 0x59, 0x5B, 0x5C, 0x5D, 0x5E, 0x60, 0x61, 0x62, 0x63,
+		0x64, 0x65, 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75,
+		0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C, 0x7D, 0x7E, 0x7F, 0x80, 0x81, 0x82, 0x83, 0x84, 0x84,
+		0x85, 0x86, 0x87, 0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8E, 0x8F, 0x90, 0x91, 0x92, 0x93,
+		0x94, 0x95, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0x9A, 0x9B, 0x9C, 0x9D, 0x9E, 0x9F, 0x9F, 0xA0,
+		0xA1, 0xA2, 0xA3, 0xA3, 0xA4, 0xA5, 0xA6, 0xA6, 0xA7, 0xA8, 0xA9, 0xAA, 0xAA, 0xAB, 0xAC, 0xAD,
+		0xAD, 0xAE, 0xAF, 0xB0, 0xB0, 0xB1, 0xB2, 0xB3, 0xB3, 0xB4, 0xB5, 0xB6, 0xB6, 0xB7, 0xB8, 0xB8,
+		0xB9, 0xBA, 0xBB, 0xBB, 0xBC, 0xBD, 0xBD, 0xBE, 0xBF, 0xBF, 0xC0, 0xC1, 0xC2, 0xC2, 0xC3, 0xC4,
+		0xC4, 0xC5, 0xC6, 0xC6, 0xC7, 0xC8, 0xC8, 0xC9, 0xCA, 0xCA, 0xCB, 0xCC, 0xCC, 0xCD, 0xCE, 0xCE,
+		0xCF, 0xD0, 0xD0, 0xD1, 0xD2, 0xD2, 0xD3, 0xD4, 0xD4, 0xD5, 0xD6, 0xD6, 0xD7, 0xD7, 0xD8, 0xD9,
+		0xD9, 0xDA, 0xDB, 0xDB, 0xDC, 0xDC, 0xDD, 0xDE, 0xDE, 0xDF, 0xE0, 0xE0, 0xE1, 0xE1, 0xE2, 0xE3,
+		0xE3, 0xE4, 0xE4, 0xE5, 0xE6, 0xE6, 0xE7, 0xE7, 0xE8, 0xE9, 0xE9, 0xEA, 0xEA, 0xEB, 0xEC, 0xEC,
+		0xED, 0xED, 0xEE, 0xEF, 0xEF, 0xF0, 0xF0, 0xF1, 0xF1, 0xF2, 0xF3, 0xF3, 0xF4, 0xF4, 0xF5, 0xF5,
+		0xF6, 0xF7, 0xF7, 0xF8, 0xF8, 0xF9, 0xF9, 0xFA, 0xFB, 0xFB, 0xFC, 0xFC, 0xFD, 0xFD, 0xFE, 0xFF
+	}
+
+	return lookup[value];
+}
+
 SDL_Window* Backend_CreateWindow(const char *title, int width, int height)
 {
 	return SDL_CreateWindow(title, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, width, height, 0);
@@ -306,7 +335,7 @@
 				{
 					for (unsigned int i = 0; i < 3; ++i)
 					{
-						*destination_pointer++ = pow((*source_pointer++ / 255.0), 1.0 / 1.8);	// Gamma correction
+						*destination_pointer++ = GammaCorrect(*source_pointer++);
 					}
 				}
 			}
@@ -332,7 +361,7 @@
 
 				for (unsigned int x = 0; x < width; ++x)
 				{
-					*destination_pointer++ = pow((double)*source_pointer++ / (total_greys - 1), 1.0 / 1.8);	// Gamma correction
+					*destination_pointer++ = GammaCorrect((*source_pointer++ * 0xFF) / (total_greys - 1));
 				}
 			}