Draw a selection marker on the terrain.

2 files changed, 16 insertions, 7 deletions

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;