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