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brender-v1.1.2/ZB/AWTMI.H

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2022-05-04 20:14:23 -05:00
/*
* Copyright (c) 1993-1995 Argonaut Technologies Limited. All rights reserved.
*
* $Id: awtmi.h 1.1 1995/08/31 16:52:47 sam Exp $
*
* Triangle renderer for arbitrary width linear texture mapping
*/
void BR_ASM_CALL
FNAME(struct temp_vertex_fixed *a,struct temp_vertex_fixed *b,struct temp_vertex_fixed *c)
{
/* v[0] and v[1] contain the (fractional) screen coordinates */
/* And comp[C_W] contain the 3-space z-value */
/* (v[0]-width/2)*comp[C_W] gives the 3-space x-values */
/* Similarly for y */
int sxa,sxb,sxc,sya,syb,syc;
int dv_int;
int offset;
int grad;
br_fixed_ls g_divisor,dp1,dp2;
int dv_int_nocarry;
int dv_int_carry;
int v_int_current;
int direction;
int texture_height;
int colour_width;
texture_height = zb.material->colour_map->height;
zb.awsl.texture_stride = zb.material->colour_map->row_bytes;
zb.awsl.texture_width = zb.material->colour_map->width;
/* Optimal sort of 3 elements? */
if (a->v[1]>b->v[1]) {
if (b->v[1]>c->v[1]) {
swap(struct temp_vertex_fixed *,a,c);
} else {
if (a->v[1]>c->v[1]) {
swap(struct temp_vertex_fixed *,a,b);
swap(struct temp_vertex_fixed *,b,c);
} else {
swap(struct temp_vertex_fixed *,a,b);
}
}
} else {
if (b->v[1]>c->v[1]) {
if (a->v[1]>c->v[1]) {
swap(struct temp_vertex_fixed *,b,c);
swap(struct temp_vertex_fixed *,a,b);
} else {
swap(struct temp_vertex_fixed *,b,c);
}
}
}
sxa = sar16(a->v[0]);
sya = sar16(a->v[1]);
sxb = sar16(b->v[0]);
syb = sar16(b->v[1]);
sxc = sar16(c->v[0]);
syc = sar16(c->v[1]);
zb.top.x = sxb-sxa;
zb.top.y = syb-sya;
zb.bot.x = sxc-sxb;
zb.bot.y = syc-syb;
zb.main.x = sxc-sxa;
zb.main.y = syc-sya;
zb.awsl.texture_stride = zb.material->colour_map->row_bytes;
zb.awsl.texture_width = zb.material->colour_map->width;
texture_height = zb.material->colour_map->height;
zb.awsl.texture_size = zb.awsl.texture_stride*texture_height;
zb.awsl.texture_start = zb.texture_buffer;
colour_width = zb.row_width/BPP;
zb.main.grad = zb.main.x*_reciprocal[zb.main.y];
zb.main.d_f = zb.main.grad << 16;
grad = sar16(zb.main.grad);
zb.main.d_i = grad+colour_width;
zb.top.grad = zb.top.y ? zb.top.x*_reciprocal[zb.top.y] : 0;
zb.top.d_f = zb.top.grad << 16;
zb.top.d_i = sar16(zb.top.grad)+colour_width;
zb.main.f = zb.top.f = 0x80000000;
offset = high16(a->v[X])+high16(a->v[Y])*colour_width;
zb.awsl.start = zb.awsl.end = zb.colour_buffer+offset*BPP;
zb.awsl.zstart = (char *)zb.depth_buffer+offset*2;
zb.top.count = syb-sya;
zb.bot.f = 0x80000000;
zb.bot.grad = zb.bot.y ? zb.bot.x*_reciprocal[zb.bot.y] : 0;
zb.bot.d_f = zb.bot.grad << 16;
zb.bot.d_i = sar16(zb.bot.grad)+colour_width;
zb.bot.count = syc-syb;
g_divisor = zb.top.x*zb.main.y-zb.main.x*zb.top.y;
if (!g_divisor) return;
direction = zb.top.count && zb.top.grad>=zb.main.grad ||
zb.bot.count && zb.bot.grad<zb.main.grad;
#define PARAM_SETUP(param,p) {\
dp1 = b->p-a->p;\
dp2 = c->p-a->p;\
param.grad_x = SafeFixedMac2Div(dp1,zb.main.y,-dp2,zb.top.y,g_divisor);\
param.grad_y = SafeFixedMac2Div(dp2,zb.top.x,-dp1,zb.main.x,g_divisor);\
param.current = a->p+param.grad_x/2;\
param.d_nocarry = BrFixedToInt(zb.main.grad)*param.grad_x+param.grad_y;\
param.d_carry = param.d_nocarry+param.grad_x;\
}
#if LIGHT
PARAM_SETUP(zb.pi,comp[C_I]);
#endif
#if ZB
PARAM_SETUP(zb.pz,v[Z]);
#endif
PARAM_SETUP(zb.pu,comp[C_U]);
PARAM_SETUP(zb.pv,comp[C_V]);
zb.awsl.du_nocarry = zb.pu.d_nocarry << 16;
zb.awsl.dv_nocarry = zb.pv.d_nocarry << 16;
zb.awsl.du_carry = zb.pu.d_carry << 16;
zb.awsl.dv_carry = zb.pv.d_carry << 16;
zb.awsl.u_current = zb.pu.current << 16;
zb.awsl.v_current = zb.pv.current << 16;
/*
* Per scan line increments
*/
if (powerof2(zb.awsl.texture_width)) {
zb.awsl.du_int_nocarry = (sar16(zb.pu.d_nocarry) & zb.awsl.texture_width-1)
-zb.awsl.texture_width;
zb.awsl.du_int_carry = (sar16(zb.pu.d_carry) & zb.awsl.texture_width-1)
-zb.awsl.texture_width;
zb.awsl.u_int_current = sar16(zb.pu.current) & zb.awsl.texture_width-1;
} else {
zb.awsl.du_int_nocarry = sar16(zb.pu.d_nocarry) % zb.awsl.texture_width;
zb.awsl.du_int_carry = sar16(zb.pu.d_carry) % zb.awsl.texture_width;
zb.awsl.u_int_current = sar16(zb.pu.current) % zb.awsl.texture_width;
if (zb.awsl.du_int_nocarry>=0) zb.awsl.du_int_nocarry -= zb.awsl.texture_width;
if (zb.awsl.du_int_carry>=0) zb.awsl.du_int_carry -= zb.awsl.texture_width;
if (zb.awsl.u_int_current<0) zb.awsl.u_int_current += zb.awsl.texture_width;
}
if (powerof2(texture_height)) {
dv_int_nocarry = (sar16(zb.pv.d_nocarry) & texture_height-1)
-texture_height;
dv_int_carry = (sar16(zb.pv.d_carry) & texture_height-1)
-texture_height;
v_int_current = sar16(zb.pv.current) & texture_height-1;
} else {
dv_int_nocarry = sar16(zb.pv.d_nocarry) % texture_height;
dv_int_carry = sar16(zb.pv.d_carry) % texture_height;
v_int_current = sar16(zb.pv.current) % texture_height;
if (dv_int_nocarry>=0) dv_int_nocarry -= texture_height;
if (dv_int_carry>=0) dv_int_carry -= texture_height;
if (v_int_current<0) v_int_current += texture_height;
}
zb.awsl.dsource_nocarry = zb.awsl.du_int_nocarry*BPP+zb.awsl.texture_stride*dv_int_nocarry;
zb.awsl.dsource_carry = zb.awsl.du_int_carry*BPP+zb.awsl.texture_stride*dv_int_carry;
zb.awsl.source_current = zb.texture_buffer+zb.awsl.u_int_current*BPP+zb.awsl.texture_stride*v_int_current;
zb.awsl.u_int_current += 0x8000;
if (direction) {
zb.awsl.du = zb.pu.grad_x << 16;
zb.awsl.dv = zb.pv.grad_x << 16;
zb.awsl.du_int = sar16(zb.pu.grad_x) % zb.awsl.texture_width;
if (powerof2(texture_height))
dv_int = (sar16(zb.pv.grad_x) & texture_height-1)-texture_height;
else {
dv_int = sar16(zb.pv.grad_x) % texture_height;
if (dv_int>=0) dv_int -= texture_height;
}
} else {
zb.awsl.du = -zb.pu.grad_x << 16;
zb.awsl.dv = -zb.pv.grad_x << 16;
zb.awsl.du_int = sar16(-zb.pu.grad_x) % zb.awsl.texture_width;
if (powerof2(texture_height)) {
dv_int = (sar16(-zb.pv.grad_x) & texture_height-1)-texture_height;
} else
dv_int = sar16(-zb.pv.grad_x) % texture_height;
if (dv_int>=0) dv_int -= texture_height;
}
if (zb.awsl.du_int>=0) zb.awsl.du_int -= zb.awsl.texture_width;
zb.awsl.dsource = zb.awsl.du_int*BPP+zb.awsl.texture_stride*dv_int;
zb.awsl.edge = &zb.top;
ASSERT(zb.awsl.source_current>=zb.awsl.texture_start);
TNAME();
zb.awsl.end = zb.colour_buffer+high16(b->v[X])*BPP+high16(b->v[Y])*zb.row_width;
zb.awsl.edge = &zb.bot;
ASSERT(zb.awsl.source_current>=zb.awsl.texture_start);
TNAME();
}

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