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Added two-sided polygon flag and back-face culling to Model 3 video emulation [Naibo Zhang]

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From: naibo zhang [naibo_zhang@hotmail.com]
Sent: Tuesday, October 13, 2009 6:11 PM
To: submit@mamedev.org
Subject: Sega Model-3 backface culling & stepstag rename

Sega Model-3 video emulation improvement: figured out the flag bit indicating a single-/double-side polygon. Added backface culling code. Some graphic flickering glitches are gone.
This commit is contained in:
Phil Bennett 2009-10-21 18:18:54 +00:00
parent 4e0c48083f
commit c089acef32
1 changed files with 56 additions and 44 deletions
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100
src/mame/video/model3.c
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@ -1124,7 +1124,7 @@ static void draw_model(UINT32 addr)
UINT32 *model = (addr >= 0x100000) ? &model3_vrom[addr] : &polygon_ram[addr];
UINT32 header[7];
int index = 0;
int last_polygon = FALSE;
int last_polygon = FALSE, back_face = FALSE;
int num_vertices;
int i, v, vi;
float fixed_point_fraction;
@ -1216,7 +1216,7 @@ static void draw_model(UINT32 addr)
sn[1] *= coordinate_system[1][2];
sn[2] *= coordinate_system[2][0];
/* TODO: backface culling */
/* TODO: depth bias */
/* transform vertices */
for (i = 0; i < num_vertices; i++)
{
@ -1245,56 +1245,68 @@ static void draw_model(UINT32 addr)
num_vertices = clip_polygon(clip_vert, num_vertices, clip_plane[3], clip_vert);
num_vertices = clip_polygon(clip_vert, num_vertices, clip_plane[4], clip_vert);
/* homogeneous Z-divide, screen-space transformation */
for(i=0; i < num_vertices; i++) {
float ooz = 1.0f / clip_vert[i].pz;
clip_vert[i].x = ((clip_vert[i].x * ooz) * viewport_focal_length) + center_x;
clip_vert[i].y = ((clip_vert[i].y * ooz) * viewport_focal_length) + center_y;
/* backface culling */
if( (header[6] & 0x800000) && (!(header[1] & 0x0010)) ) {
if(sn[0]*clip_vert[0].x + sn[1]*clip_vert[0].y + sn[2]*clip_vert[0].pz >0)
back_face = 1;
else
back_face = 0;
}
else
back_face = 0; //no culling for transparent or two-sided polygons
// lighting
if ((header[6] & 0x10000) == 0)
{
dot = dot_product3(sn, parallel_light);
intensity = ((dot * parallel_light_intensity) + ambient_light_intensity) * 256.0f;
if (intensity > 256)
if(!back_face) {
/* homogeneous Z-divide, screen-space transformation */
for(i=0; i < num_vertices; i++) {
float ooz = 1.0f / clip_vert[i].pz;
clip_vert[i].x = ((clip_vert[i].x * ooz) * viewport_focal_length) + center_x;
clip_vert[i].y = ((clip_vert[i].y * ooz) * viewport_focal_length) + center_y;
}
// lighting
if ((header[6] & 0x10000) == 0)
{
dot = dot_product3(sn, parallel_light);
intensity = ((dot * parallel_light_intensity) + ambient_light_intensity) * 256.0f;
if (intensity > 256)
{
intensity = 256;
}
if (intensity < 0)
{
intensity = 0;
}
}
else
{
// apply luminosity
intensity = 256;
}
if (intensity < 0)
for (i=2; i < num_vertices; i++)
{
intensity = 0;
memcpy(&tri.v[0], &clip_vert[0], sizeof(poly_vertex));
memcpy(&tri.v[1], &clip_vert[i-1], sizeof(poly_vertex));
memcpy(&tri.v[2], &clip_vert[i], sizeof(poly_vertex));
tri.texture_x = ((header[4] & 0x1f) << 1) | ((header[5] >> 7) & 0x1);
tri.texture_y = (header[5] & 0x1f);
tri.texture_width = ((header[3] >> 3) & 0x7);
tri.texture_height = (header[3] & 0x7);
tri.texture_format = (header[6] >> 7) & 0x7;
tri.transparency = polygon_transparency;
tri.intensity = intensity;
tri.color = color;
tri.param = 0;
tri.param |= (header[4] & 0x40) ? TRI_PARAM_TEXTURE_PAGE : 0;
tri.param |= (header[6] & 0x4000000) ? TRI_PARAM_TEXTURE_ENABLE : 0;
tri.param |= (header[2] & 0x2) ? TRI_PARAM_TEXTURE_MIRROR_U : 0;
tri.param |= (header[2] & 0x1) ? TRI_PARAM_TEXTURE_MIRROR_V : 0;
tri.param |= (header[6] & 0x80000000) ? TRI_PARAM_ALPHA_TEST : 0;
render_one(&tri);
}
}
else
{
// apply luminosity
intensity = 256;
}
for (i=2; i < num_vertices; i++)
{
memcpy(&tri.v[0], &clip_vert[0], sizeof(poly_vertex));
memcpy(&tri.v[1], &clip_vert[i-1], sizeof(poly_vertex));
memcpy(&tri.v[2], &clip_vert[i], sizeof(poly_vertex));
tri.texture_x = ((header[4] & 0x1f) << 1) | ((header[5] >> 7) & 0x1);
tri.texture_y = (header[5] & 0x1f);
tri.texture_width = ((header[3] >> 3) & 0x7);
tri.texture_height = (header[3] & 0x7);
tri.texture_format = (header[6] >> 7) & 0x7;
tri.transparency = polygon_transparency;
tri.intensity = intensity;
tri.color = color;
tri.param = 0;
tri.param |= (header[4] & 0x40) ? TRI_PARAM_TEXTURE_PAGE : 0;
tri.param |= (header[6] & 0x4000000) ? TRI_PARAM_TEXTURE_ENABLE : 0;
tri.param |= (header[2] & 0x2) ? TRI_PARAM_TEXTURE_MIRROR_U : 0;
tri.param |= (header[2] & 0x1) ? TRI_PARAM_TEXTURE_MIRROR_V : 0;
tri.param |= (header[6] & 0x80000000) ? TRI_PARAM_ALPHA_TEST : 0;
render_one(&tri);
}
++polynum;
};