From 0986cf8f33df8926dd8da67f98ed18f696141313 Mon Sep 17 00:00:00 2001
From: Jon Bergli Heier <snakebite@jvnv.net>
Date: Mon, 11 Apr 2011 22:06:54 +0200
Subject: Draw a selection marker on the terrain.

---
 scene.cpp                     |  25 +++++++++++++------------
 scene.h                       |   2 +-
 shaders/terrain_fragment.glsl |  18 ++++++++++++++----
 shaders/terrain_vertex.glsl   |   5 ++---
 textures/cross.png            | Bin 0 -> 2144 bytes
 5 files changed, 30 insertions(+), 20 deletions(-)
 create mode 100644 textures/cross.png

diff --git a/scene.cpp b/scene.cpp
index 180c90d..f994627 100644
--- a/scene.cpp
+++ b/scene.cpp
@@ -35,12 +35,15 @@ Scene::Scene() {
 	glUniform1i(tex1loc, 1);
 	GLint tex2loc = glGetUniformLocation(terrain_program.get_program(), "tex[2]");
 	glUniform1i(tex2loc, 2);
+	GLint markloc = glGetUniformLocation(terrain_program.get_program(), "marktex");
+	glUniform1i(markloc, 3);
 	glUseProgram(0);
 
 	/* load textures */
 	grass_texture = load_texture("textures/zooboing-366-grass.jpg");
 	rock_texture = load_texture("textures/zooboing-825-stone-modified.jpg");
 	soil_texture = load_texture("textures/zooboing-469-sand-modified.jpg");
+	marker_texture = load_texture("textures/cross.png");
 
 	/* load heightmap */
 	SDL_Surface *hm = IMG_Load("heightmap.png");
@@ -250,7 +253,6 @@ void Scene::render() {
 	CEGUI::System::getSingleton().injectTimePulse(0.001*(float)steps);
 
 	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-	glLoadIdentity();
 	video::persp();
 
 	unsigned char *keystate = SDL_GetKeyState(NULL);
@@ -316,6 +318,13 @@ void Scene::render() {
 	unsigned int chunks_rendered = 0;
 	if(terrain) {
 		terrain_program.use();
+		GLint show_sel = glGetUniformLocation(terrain_program.get_program(), "show_sel");
+		glUniform1i(show_sel, show_selection ? 1 : 0);
+		if(show_selection) {
+			GLint selpos = glGetUniformLocation(terrain_program.get_program(), "selpos");
+			glUniform3f(selpos, selected.x, selected.y, selected.z);
+		}
+
 		glEnable(GL_TEXTURE_2D);
 
 		glActiveTexture(GL_TEXTURE0);
@@ -327,6 +336,9 @@ void Scene::render() {
 		glActiveTexture(GL_TEXTURE2);
 		glBindTexture(GL_TEXTURE_2D, soil_texture);
 
+		glActiveTexture(GL_TEXTURE3);
+		glBindTexture(GL_TEXTURE_2D, marker_texture);
+
 		std::queue<Quadtree::QuadChunk*> q;
 		q.push(qt->root);
 		while(!q.empty()) {
@@ -386,17 +398,6 @@ void Scene::render() {
 		selected = Vector3(px, py, pz);
 		show_selection = true;
 	}
-	if(show_selection) {
-		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();
diff --git a/scene.h b/scene.h
index d494994..95ae158 100644
--- a/scene.h
+++ b/scene.h
@@ -34,7 +34,7 @@ class Scene {
 
 		GLShaderProgram terrain_program;
 
-		GLuint grass_texture, rock_texture, soil_texture;
+		GLuint grass_texture, rock_texture, soil_texture, marker_texture;
 
 		Scene();
 		~Scene();
diff --git a/shaders/terrain_fragment.glsl b/shaders/terrain_fragment.glsl
index 2d02dc8..0925c6b 100644
--- a/shaders/terrain_fragment.glsl
+++ b/shaders/terrain_fragment.glsl
@@ -1,22 +1,32 @@
 #version 120
 
-varying vec3 normal, light_pos;
-varying float y;
+varying vec3 normal, light_pos, pos;
 
 uniform sampler2D tex[3];
+uniform sampler2D marktex;
+uniform vec3 selpos;
+uniform bool show_sel;
 
 void main() {
 	vec3 n = normalize(normal);
 	float diffuse = max(dot(n, light_pos), 0.5);
 
-	float f1 = clamp((y-15.0) / 3.0, 0.0, 1.0);
-	float f2 = clamp((y-2) / 3.0, 0.0, 1.0);
+	float f1 = clamp((pos.y-15.0) / 3.0, 0.0, 1.0);
+	float f2 = clamp((pos.y-2) / 3.0, 0.0, 1.0);
 
 	vec4 t0 = texture2D(tex[0], gl_TexCoord[0].st);
 	vec4 t1 = texture2D(tex[1], gl_TexCoord[0].st);
 	vec4 t2 = texture2D(tex[2], gl_TexCoord[0].st);
 
 	gl_FragColor = mix(mix(t2, t0, f2), t1, f1) * diffuse;
+
+	/* selection marker */
+	if(show_sel &&
+		pos.x >= selpos.x-1 && pos.x <= selpos.x+1 &&
+		pos.z >= selpos.z-1 && pos.z <= selpos.z+1) {
+		vec2 st = vec2((pos.x + 1 - selpos.x) / 2, (pos.z + 1 - selpos.z) / 2);
+		gl_FragColor += texture2D(marktex, st);
+	}
 }
 
 /* vim: set syn=glsl: */
diff --git a/shaders/terrain_vertex.glsl b/shaders/terrain_vertex.glsl
index e53c432..5fcd17b 100644
--- a/shaders/terrain_vertex.glsl
+++ b/shaders/terrain_vertex.glsl
@@ -1,12 +1,11 @@
 #version 120
 
-varying vec3 normal, light_pos;
-varying float y;
+varying vec3 normal, light_pos, pos;
 
 void main() {
 	normal = gl_Normal;
 	light_pos = vec3(0, 1, 0);
-	y = gl_Vertex.y;
+	pos = gl_Vertex.xyz;
 
 	gl_TexCoord[0] = gl_MultiTexCoord0;
 	gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
diff --git a/textures/cross.png b/textures/cross.png
new file mode 100644
index 0000000..2a50c6c
Binary files /dev/null and b/textures/cross.png differ
-- 
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