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[Add] Documented opengl file, explained coordinate system in use.

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This commit is contained in:
Allanis 2014-05-16 14:44:21 +01:00
parent 090d9535c4
commit 6758fd9393
2 changed files with 36 additions and 11 deletions
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27
src/opengl.c
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@ -1,3 +1,30 @@
/**
* @file opengl.c
*
* @brief This file handles most of the more generic opengl functions.
*
* The main way to work with opengl in lephisto is to create glTextures and then
* use the blit functions to draw them on the screen. This system will handle
* relative and absolute positions.
*
* There are two coordinate systems: relative and absolute.
*
* Relative:
* -- Everything is drawn relative to the player, if it doesn't fit on the
* screen it is clipped.
* -- Origin (0., 0.) would be ontop of the player.
*
* Absolute:
* -- Everything is drawn in "screen coordinates".
* -- (0., 0.) is bottom left.
* -- (SCREEN_W, SCREEN_H) is top right.
*
* Note that the game actually uses a third type of coordinate for when using
* raw commands. In this third type, the (0., 0.) is actually in middle of the
* screen. (-SCREEN_W/2., -SCREEN_H/2.) is bottom left and
* (-SCREEN_W/2., -SCREEN_H/2.) is top right.
*/
#include <SDL/SDL.h>
#include <SDL/SDL_image.h>
#include "SDL_version.h"

20
src/opengl.h
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@ -7,15 +7,15 @@
/* Recommended for compatibility bullshit. */
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
# define RMASK 0xff000000
# define GMASK 0x00ff0000
# define BMASK 0x0000ff00
# define AMASK 0x000000ff
# define RMASK 0xff000000 /**< Red bit mask. */
# define GMASK 0x00ff0000 /**< Green bit mask. */
# define BMASK 0x0000ff00 /**< Blue bit mask. */
# define AMASK 0x000000ff /**< Alpha bit mask. */
#else
# define RMASK 0x000000ff
# define GMASK 0x0000ff00
# define BMASK 0x00ff0000
# define AMASK 0xff000000
# define RMASK 0x000000ff /**< Red bit mask. */
# define GMASK 0x0000ff00 /**< Green bit mask. */
# define BMASK 0x00ff0000 /**< Blue bit mask. */
# define AMASK 0xff000000 /**< Alpha bit mask. */
#endif
#define RGBAMASK RMASK,GMASK,BMASK,AMASK
@ -33,8 +33,6 @@
#define gl_has(f) (gl_screen.flags & (f)) /**< Check for the flag. */
/**
* @struct glInfo
*
* @brief Store data about the current opengl environment.
*/
typedef struct glInfo_ {
@ -138,7 +136,7 @@ void gl_getSpriteFromDir(int* x, int* y, const glTexture* t, const double dir);
void gl_screenshot(const char* filename);
int SDL_savePNG(SDL_Surface* surface, const char* file);
/*#if DEBUG == 1 */
void gl_checkErr(void);
void gl_checkErr(void); /**< Hack to ignore errors when debugging. */
/*#else */
/*#define gl_checkErr() */
/*#endif */