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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include "graphics/tinygl/zgl.h"
namespace TinyGL {
void GLContext::glopFog(GLParam *p) {
int pname = p[1].i;
switch (pname) {
case TGL_FOG_MODE:
switch (p[2].i) {
case TGL_LINEAR:
case TGL_EXP:
case TGL_EXP2:
fog_mode = p[2].i;
break;
default:
error("tglFog: unknown fog mode");
return;
}
break;
case TGL_FOG_DENSITY:
if (p[2].f < 0.0f) {
error("tglFog: fog density negate param");
return;
}
fog_density = p[2].f;
break;
case TGL_FOG_START:
fog_start = p[2].f;
break;
case TGL_FOG_END:
fog_end = p[2].f;
break;
case TGL_FOG_COLOR:
fog_color = Vector4(clampf(p[2].f, 0.0f, 1.0f),
clampf(p[3].f, 0.0f, 1.0f),
clampf(p[4].f, 0.0f, 1.0f),
clampf(p[5].f, 0.0f, 1.0f));
break;
default:
error("tglFog: param not implemented");
return;
}
}
void GLContext::gl_calc_fog_factor(GLVertex *v) {
float eye_distance = sqrtf(v->ec.X * v->ec.X + v->ec.Y * v->ec.Y + v->ec.Z * v->ec.Z);
switch (fog_mode) {
case TGL_LINEAR: {
float fog_distance = 1.0f;
if (fog_start != fog_end)
fog_distance /= (fog_end - fog_start);
v->fog_factor = (fog_end - eye_distance) * fog_distance;
}
break;
case TGL_EXP:
v->fog_factor = expf(-fog_density * eye_distance);
break;
case TGL_EXP2:
v->fog_factor = expf(-(fog_density * fog_density * eye_distance * eye_distance));
break;
default:
v->fog_factor = 0;
break;
}
v->fog_factor = clampf(v->fog_factor, 0.0f, 1.0f);
}
} // end of namespace TinyGL
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