GRAPHICS: Add shadow mode to grim actors [OpenGLS]

engines/grim/gfx_opengl_shaders.cpp

@@ -456,6 +456,26 @@ void GfxOpenGLS::startActorDraw(const Actor *actor) {
 		_actorProgram->setUniform("texcropZBuf", _zBufTexCrop);
 		_actorProgram->setUniform("screenSize", Math::Vector2d(_screenWidth, _screenHeight));
 
+		if (_currentShadowArray) {
+			const Sector *shadowSector = _currentShadowArray->planeList.front().sector;
+			const Math::Vector3d color = Math::Vector3d(_shadowColorR, _shadowColorG, _shadowColorB) / 255.f;
+			Math::Vector3d normal = shadowSector->getNormal();
+			if (!_currentShadowArray->dontNegate)
+				normal = -normal;
+
+			_actorProgram->setUniform("shadow._active", true);
+			_actorProgram->setUniform("shadow._color", color);
+			_actorProgram->setUniform("shadow._light", _currentShadowArray->pos);
+			_actorProgram->setUniform("shadow._point", shadowSector->getVertices()[0]);
+			_actorProgram->setUniform("shadow._normal", normal);
+
+			glDisable(GL_DEPTH_TEST);
+			glDisable(GL_BLEND);
+			glEnable(GL_POLYGON_OFFSET_FILL);
+		} else {
+			_actorProgram->setUniform("shadow._active", false);
+		}
+
 		_actorProgram->setUniform("lightsEnabled", _lightsEnabled);
 		if (_lightsEnabled) {
 			for (int i = 0; i < _maxLights; ++i) {
@@ -482,6 +502,7 @@ void GfxOpenGLS::startActorDraw(const Actor *actor) {
 
 void GfxOpenGLS::finishActorDraw() {
 	_currentActor = NULL;
+	glDisable(GL_POLYGON_OFFSET_FILL);
 }
 
 void GfxOpenGLS::setShadow(Shadow *shadow) {
@@ -654,7 +675,8 @@ void GfxOpenGLS::drawMesh(const Mesh *mesh) {
 			faces += 3 * (mesh->_faces[i]._numVertices - 2);
 		}
 
-		actorShader->setUniform("textured", face->_texVertices ? GL_TRUE : GL_FALSE);
+		bool textured = face->_texVertices && ! _currentShadowArray;
+		actorShader->setUniform("textured", textured ? GL_TRUE : GL_FALSE);
 		actorShader->setUniform("texScale", Math::Vector2d(_selectedTexture->_width, _selectedTexture->_height));
 
 		glDrawArrays(GL_TRIANGLES, *(int *)face->_userData, faces);

engines/grim/shaders/grim_actor.vertex

@@ -4,6 +4,14 @@ struct light {
 	vec4 _color;
 };
 
+struct shadow_info {
+	bool _active;
+	vec3 _color;
+	vec3 _light;
+	vec3 _point;
+	vec3 _normal;
+};
+
 const int maxLights = 8;
 const float DIFFUSE_FACTOR = 0.8;
 
@@ -19,6 +27,7 @@ uniform highp mat4 extraMatrix;
 uniform highp vec2 texScale;
 uniform bool textured;
 uniform light lights[maxLights];
+uniform shadow_info shadow;
 uniform bool lightsEnabled;
 
 out vec2 Texcoord;
@@ -32,6 +41,15 @@ void main()
 	      extraMatrix *
 	      pos;
 
+	// See http://en.wikipedia.org/wiki/Line-plane_intersection
+	if (shadow._active) {
+		pos /= pos.w;
+		vec3 l = pos.xyz - shadow._light;
+		float d = dot(shadow._point - shadow._light, shadow._normal) / dot(l, shadow._normal);
+		vec3 p = shadow._light + d * l;
+		pos = vec4(p, 1.0);
+	}
+
 	gl_Position = projMatrix * viewMatrix * pos;
 
 	if (textured) {
@@ -69,5 +87,8 @@ void main()
 		Color = color * vec4(light, 1.0);
 	} else */ {
 		Color = color;
+		if (shadow._active) {
+			Color = vec4(shadow._color, 1.0);
+		}
 	}
 }