1 files changed, 53 insertions, 0 deletions
diff --git a/shaders/forest.frag b/shaders/forest.frag
new file mode 100644
index 0000000..1cad806
--- /dev/null
+++ b/shaders/forest.frag
@@ -0,0 +1,53 @@
+#version 150
+#extension GL_ARB_explicit_attrib_location : enable
+#extension GL_ARB_explicit_uniform_location : enable
+
+layout(location = 0) out vec4 frag_color ;
+
+uniform mat4 mvMatrix ;
+uniform mat4 pjMatrix ;
+layout(location = 6) uniform sampler2D texture ;
+layout(location = 7) uniform vec4 light ;
+layout(location = 10) uniform vec4 globalAmbient ;
+
+uniform float dX ;
+uniform float dY ;
+
+in vec2 texposition ;
+in vec3 normal ;
+in vec4 frag_position ;
+
+vec4 sample(float xc,float yc) {
+   return texture2D(texture,texposition + vec2(xc,yc));
+}
+
+vec3 calNormChange( vec3 norm, vec3 down, vec3 right ) {
+    float x00 = 1 - sample(-dX, dY).a ; 
+    float x01 = 1 - sample(  0, dY).a ; 
+    float x02 = 1 - sample( dX, dY).a ; 
+
+    float x10 = 1 - sample(-dX, 0).a ; 
+    float x11 = 1 - sample(  0, 0).a ; 
+    float x12 = 1 - sample( dX, 0).a ; 
+
+    float x20 = 1 - sample(-dX,-dY).a ; 
+    float x21 = 1 - sample(  0,-dY).a ; 
+    float x22 = 1 - sample( dX,-dY).a ; 
+
+    down = ((x11 - x00) + (x11 - x01) + (x11 - x02) - (x11 - x20) - (x11 - x21) - (x11 - x22)) * down ;
+    right = ((x11 - x00) + (x11 - x10) + (x11 - x20) - (x11 - x02) - (x11 - x12) - (x11 - x22)) * right ;
+    
+    return (right*2 + down*2 + norm) / 5.0 ;
+}
+
+void main() {
+    vec3 down = vec3( 0, -1, 0 ) ;
+    vec3 right = normalize(cross( normal, down )) ;
+    down = normalize(cross( normal, right ) );
+    vec3 newNorm = calNormChange( normal, down, right ) ;
+
+    vec4 col = texture2D(texture,texposition) ;
+    float coef = max(dot( normalize(newNorm),
+                          normalize(vec3(frag_position - light)) ),0) + (globalAmbient.a/4.0) ;
+    frag_color = vec4( col.xyz * coef * globalAmbient.xyz, col.a);
+}