From f658c122374c09682d9029f0d0d76d1bfd67404b Mon Sep 17 00:00:00 2001
From: Jon Bergli Heier <snakebite@jvnv.net>
Date: Thu, 31 Mar 2011 00:33:57 +0200
Subject: Simple terrain click-selection using gluUnProject().

---
 main.cpp | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 50 insertions(+), 5 deletions(-)

diff --git a/main.cpp b/main.cpp
index b653427..36ddb10 100644
--- a/main.cpp
+++ b/main.cpp
@@ -33,7 +33,7 @@ struct hit_record {
 };
 
 // TODO: reimplement
-int select(Quadtree& qt, int x, int y) {
+int _select(Quadtree& qt, int x, int y) {
 	y = 600-y;
 	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
@@ -95,9 +95,33 @@ int select(Quadtree& qt, int x, int y) {
 	return 0;
 }
 
+bool select(Quadtree& qt, int x, int y, float& px, float& py, float& pz) {
+	GLint view[4] = {0};
+	GLdouble mvmatrix[16] = {0}, projmatrix[16] = {0};
+	glGetDoublev(GL_PROJECTION_MATRIX, projmatrix);
+	glGetDoublev(GL_MODELVIEW_MATRIX, mvmatrix);
+	glGetIntegerv(GL_VIEWPORT, view);
+
+	y = view[3] - y - 1;
+
+	float z;
+	glReadBuffer(GL_BACK);
+	glReadPixels(x, y, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &z);
+
+	GLdouble _px, _py, _pz;
+	if(gluUnProject(x, y, z, mvmatrix, projmatrix, view, &_px, &_py, &_pz) == GLU_TRUE) {
+		px = _px;
+		py = _py;
+		pz = _pz;
+		return true;
+	}
+
+	return false;
+}
+
 int main(int argc, char **argv) {
-	video::width = 800;
-	video::height = 600;
+	video::width = 1280;
+	video::height = 720;
 	video::init();
 
 	font = new FTTextureFont("font.ttf");
@@ -150,6 +174,7 @@ int main(int argc, char **argv) {
 	unsigned int last_time = SDL_GetTicks();
 	/*boost::timer t;
 	double last_time = 0;*/
+	Vector3 selected;
 	while(running) {
 		unsigned int time = SDL_GetTicks();
 		//double time = t.elapsed();
@@ -157,6 +182,8 @@ int main(int argc, char **argv) {
 		unsigned int steps = time - last_time + 1;
 		//double steps = (time - last_time) * 1000;
 		last_time = time;
+		bool do_select = 0;
+		int sx, sy;
 		while(SDL_PollEvent(&event)) {
 			switch(event.type) {
 				case SDL_QUIT:
@@ -173,6 +200,7 @@ int main(int argc, char **argv) {
 						case SDLK_KP_PLUS:
 							delete qt;
 							qt = new Quadtree(hm->w, hm->h, heightmap, ++level);
+							level = qt->levels;
 							break;
 						case SDLK_KP_MINUS:
 							if(level > 0) {
@@ -190,6 +218,9 @@ int main(int argc, char **argv) {
 				case SDL_MOUSEBUTTONUP:
 					switch(event.button.button) {
 						case SDL_BUTTON_LEFT:
+							sx = event.button.x;
+							sy = event.button.y;
+							do_select = true;
 							// TODO: reimplement selection
 							break;
 						case SDL_BUTTON_WHEELUP:
@@ -255,7 +286,7 @@ int main(int argc, char **argv) {
 					scene.yvel -= 9.81 * steps / 85000;
 				if(scene.yvel < -.5)
 					scene.yvel = -.5;
-				scene.pos.y += scene.yvel;
+				scene.pos.y += scene.yvel * steps;
 				if(scene.pos.y < y) {
 					scene.pos.y = y;
 					scene.yvel = 0;
@@ -304,10 +335,24 @@ int main(int argc, char **argv) {
 		glDisable(GL_TEXTURE_2D);
 		glDisable(GL_LIGHTING);
 
+		float px, py, pz;
+		if(do_select && select(*qt, sx, sy, px, py, pz)) {
+			selected = Vector3(px, py, pz);
+		}
+		glColor3f(1, 0, 0);
+		glBegin(GL_TRIANGLE_FAN);
+			glVertex3f(selected.x, selected.y, selected.z);
+			glVertex3f(selected.x+.5, selected.y+1, selected.z-.5);
+			glVertex3f(selected.x+.5, selected.y+1, selected.z+.5);
+			glVertex3f(selected.x-.5, selected.y+1, selected.z+.5);
+			glVertex3f(selected.x-.5, selected.y+1, selected.z-.5);
+			glVertex3f(selected.x+.5, selected.y+1, selected.z-.5);
+		glEnd();
+
 		video::ortho();
 		float height = font->LineHeight();
 		glColor3f(1, 1, 1);
-		glTranslatef(0, 600-height, 0);
+		glTranslatef(0, video::height-height, 0);
 		font->Render((boost::format("%dx%d  %d levels  %d nodes  tree creation time: %f  steps: %d")
 					% qt->width % qt->height % qt->levels % qt->nodes % qt->init_time % steps).str().c_str());
 		//glTranslatef(0, height, 0);
-- 
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