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engines/wintermute/base/gfx/tinygl/shadow_volume_tinygl.cpp

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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/>.
+ *
+ */
+
+/*
+ * This file is based on WME.
+ * http://dead-code.org/redir.php?target=wme
+ * Copyright (c) 2003-2013 Jan Nedoma and contributors
+ */
+
+#include "engines/wintermute/base/base_game.h"
+#include "engines/wintermute/dcgf.h"
+
+#if defined(USE_TINYGL)
+
+#include "engines/wintermute/base/gfx/tinygl/base_render_tinygl.h"
+#include "engines/wintermute/base/gfx/tinygl/shadow_volume_tinygl.h"
+
+namespace Wintermute {
+
+//////////////////////////////////////////////////////////////////////////
+ShadowVolumeTinyGL::ShadowVolumeTinyGL(BaseGame *inGame) : ShadowVolume(inGame) {
+}
+
+//////////////////////////////////////////////////////////////////////////
+ShadowVolumeTinyGL::~ShadowVolumeTinyGL() {
+}
+
+//////////////////////////////////////////////////////////////////////////
+bool ShadowVolumeTinyGL::render() {
+	tglBindTexture(TGL_TEXTURE_2D, 0);
+	tglDisable(TGL_TEXTURE_2D);
+	_game->_renderer3D->_lastTexture = nullptr;
+
+	tglEnableClientState(TGL_VERTEX_ARRAY);
+	tglVertexPointer(3, TGL_FLOAT, 0, _vertices.getData());
+	tglDrawArrays(TGL_TRIANGLES, 0, _vertices.getSize());
+	tglDisableClientState(TGL_VERTEX_ARRAY);
+
+	return true;
+}
+
+//////////////////////////////////////////////////////////////////////////
+bool ShadowVolumeTinyGL::renderToStencilBuffer() {
+	// Disable z-buffer/color writes (note: z-testing still occurs), and enable the
+	// stencil-buffer
+	tglDepthMask(TGL_FALSE);
+	tglColorMask(TGL_FALSE, TGL_FALSE, TGL_FALSE, TGL_FALSE);
+	tglDisable(TGL_TEXTURE_2D);
+	tglDisable(TGL_LIGHTING);
+	tglEnable(TGL_STENCIL_TEST);
+	tglEnable(TGL_CULL_FACE);
+
+	// Set up stencil compare fuction, reference value, and masks.
+	// Stencil test passes if ((ref & mask) cmpfn (stencil & mask)) is true.
+	// Note: since we set up the stencil-test to always pass, the STENCILFAIL
+	// renderstate is really not needed.
+	tglStencilFunc(TGL_ALWAYS, 0x1, 0xff);
+
+	tglShadeModel(TGL_FLAT);
+
+	tglStencilOp(TGL_KEEP, TGL_KEEP, TGL_INCR);
+
+	// Draw back-side of shadow volume in stencil/z only
+	tglFrontFace(TGL_CCW);
+	render();
+
+	// Decrement stencil buffer value
+	tglStencilOp(TGL_KEEP, TGL_KEEP, TGL_DECR);
+
+	// Draw front-side of shadow volume in stencil/z only
+	tglFrontFace(TGL_CW);
+	render();
+
+	// Restore render states
+	tglEnable(TGL_LIGHTING);
+	tglFrontFace(TGL_CCW);
+	tglShadeModel(TGL_SMOOTH);
+	tglDepthMask(TGL_TRUE);
+	tglColorMask(TGL_TRUE, TGL_TRUE, TGL_TRUE, TGL_TRUE);
+	tglDisable(TGL_STENCIL_TEST);
+	tglDisable(TGL_BLEND);
+
+	return true;
+}
+
+//////////////////////////////////////////////////////////////////////////
+bool ShadowVolumeTinyGL::renderToScene() {
+	initMask();
+
+	tglDisable(TGL_DEPTH_TEST);
+	tglEnable(TGL_STENCIL_TEST);
+	tglEnable(TGL_BLEND);
+	tglBlendFunc(TGL_SRC_ALPHA, TGL_ONE_MINUS_SRC_ALPHA);
+
+	// Only write where stencil val >= 1 (count indicates # of shadows that overlap that pixel)
+	tglStencilFunc(TGL_LEQUAL, 0x1, 0xff);
+	tglStencilOp(TGL_KEEP, TGL_KEEP, TGL_KEEP);
+
+	tglDisable(TGL_FOG);
+	tglDisable(TGL_LIGHTING);
+	tglDisable(TGL_ALPHA_TEST);
+
+	tglBindTexture(TGL_TEXTURE_2D, 0);
+
+	BaseRenderTinyGL *renderer = (BaseRenderTinyGL *)_game->_renderer3D;
+	renderer->setProjection2D();
+
+	// FIXME: CW->CCW Why it differ from OpenGL?
+	tglFrontFace(TGL_CCW);
+
+	tglEnableClientState(TGL_COLOR_ARRAY);
+	tglEnableClientState(TGL_VERTEX_ARRAY);
+
+	// Draw a big, gray square
+	tglVertexPointer(3, TGL_FLOAT, sizeof(ShadowVertex), &_shadowMask[0].x);
+	tglColorPointer(4, TGL_UNSIGNED_BYTE, sizeof(ShadowVertex), &_shadowMask[0].r);
+
+	tglDrawArrays(TGL_TRIANGLE_STRIP, 0, 4);
+
+	tglDisableClientState(TGL_COLOR_ARRAY);
+	tglDisableClientState(TGL_VERTEX_ARRAY);
+
+	// Restore render states
+	tglEnable(TGL_DEPTH_TEST);
+	tglDisable(TGL_STENCIL_TEST);
+
+	_game->_renderer3D->setup3D(nullptr, true);
+
+	// clear stencil buffer
+	tglClearStencil(0);
+	tglClear(TGL_STENCIL_BUFFER_BIT);
+
+	return true;
+}
+
+//////////////////////////////////////////////////////////////////////////
+bool ShadowVolumeTinyGL::initMask() {
+	auto *rend = _game->_renderer3D;
+
+	// bottom left
+	_shadowMask[0].x = 0.0f;
+	_shadowMask[0].y = rend->getHeight();
+	_shadowMask[0].z = 1.0f;
+
+	// top left
+	_shadowMask[1].x = 0.0f;
+	_shadowMask[1].y = 0.0f;
+	_shadowMask[1].z = 1.0f;
+
+	// bottom right
+	_shadowMask[2].x = rend->getWidth();
+	_shadowMask[2].y = rend->getHeight();
+	_shadowMask[2].z = 1.0f;
+
+	// top right
+	_shadowMask[3].x = rend->getWidth();
+	_shadowMask[3].y = 0.0f;
+	_shadowMask[3].z = 1.0f;
+
+	byte a = RGBCOLGetA(_color);
+	byte r = RGBCOLGetR(_color);
+	byte g = RGBCOLGetG(_color);
+	byte b = RGBCOLGetB(_color);
+
+	for (int i = 0; i < 4; ++i) {
+		_shadowMask[i].r = r;
+		_shadowMask[i].g = g;
+		_shadowMask[i].b = b;
+		_shadowMask[i].a = a;
+	}
+
+	return true;
+}
+
+} // namespace Wintermute
+
+#endif // defined(USE_TINYGL)