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library: Refactor viewport calculations

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Use asynchronous division with the hardware divider as an optimization.
This commit is contained in:
Antonio Niño Díaz 2022-10-24 01:41:56 +01:00
parent 15e2122514
commit eecfe1d7da
2 changed files with 39 additions and 14 deletions
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25
source/NEGeneral.c
View File

@ -7,6 +7,7 @@
#include <nds/arm9/postest.h>
#include "NEMain.h"
#include "NEMath.h"
/// @file NEGeneral.c
@ -79,16 +80,19 @@ void NE_End(void)
void NE_Viewport(int x1, int y1, int x2, int y2)
{
// Start calculating screen ratio in f32 format
ne_div_start((x2 - x1 + 1) << 12, (y2 - y1 + 1));
// Save viewport
NE_viewport = x1 | (y1 << 8) | (x2 << 16) | (y2 << 24);
GFX_VIEWPORT = NE_viewport;
NE_screenratio = divf32((x2 - x1 + 1) << 12, (y2 - y1 + 1) << 12);
MATRIX_CONTROL = GL_PROJECTION; // New projection matix for this viewport
MATRIX_IDENTITY = 0;
gluPerspectivef32(fov * DEGREES_IN_CIRCLE / 360, NE_screenratio,
ne_znear, ne_zfar);
int fovy = fov * DEGREES_IN_CIRCLE / 360;
NE_screenratio = ne_div_result();
gluPerspectivef32(fovy, NE_screenratio, ne_znear, ne_zfar);
MATRIX_CONTROL = GL_MODELVIEW;
}
@ -290,10 +294,10 @@ void NE_Process(NE_Voidfunc drawscene)
{
NE_UpdateInput();
GFX_VIEWPORT = NE_viewport;
NE_PolyFormat(31, 0, NE_LIGHT_ALL, NE_CULL_BACK, 0);
GFX_VIEWPORT = NE_viewport;
MATRIX_CONTROL = GL_PROJECTION;
MATRIX_IDENTITY = 0;
gluPerspectivef32(fov * DEGREES_IN_CIRCLE / 360, NE_screenratio,
@ -352,15 +356,8 @@ void NE_ProcessDual(NE_Voidfunc topscreen, NE_Voidfunc downscreen)
NE_PolyFormat(31, 0, NE_LIGHT_ALL, NE_CULL_BACK, 0);
NE_viewport = 0 | (0 << 8) | (255 << 16) | (191 << 24);
GFX_VIEWPORT = NE_viewport;
NE_Viewport(0, 0, 255, 191);
MATRIX_CONTROL = GL_PROJECTION;
MATRIX_IDENTITY = 0;
gluPerspectivef32(fov * DEGREES_IN_CIRCLE / 360,
floattof32(256.0 / 192.0), ne_znear, ne_zfar);
MATRIX_CONTROL = GL_MODELVIEW;
MATRIX_IDENTITY = 0;
NE_AssertPointer(topscreen, "NULL function pointer (top screen)");

28
source/NEMath.h Normal file
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@ -0,0 +1,28 @@
// SPDX-License-Identifier: MIT
//
// Copyright (c) 2008-2011, 2019, 2022 Antonio Niño Díaz
//
// This file is part of Nitro Engine
#include <nds.h>
// Internal math functions
static inline
void ne_div_start(int32_t num, int32_t den)
{
REG_DIVCNT = DIV_32_32;
while (REG_DIVCNT & DIV_BUSY);
REG_DIV_NUMER_L = num;
REG_DIV_DENOM_L = den;
}
static inline
int32_t ne_div_result(void)
{
while (REG_DIVCNT & DIV_BUSY);
return REG_DIV_RESULT_L;
}