From 21ad8ec8d63007add27bd9607e03e304be3be4e6 Mon Sep 17 00:00:00 2001
From: Kenneth Graunke <kenneth@whitecape.org>
Date: Thu, 6 Jan 2011 17:46:33 -0800
Subject: Use textureOffset

---
 src/main.cpp   |  9 ---------
 src/sobel.frag | 29 +++++++++++------------------
 src/sobel.vert |  6 +++---
 3 files changed, 14 insertions(+), 30 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index 0d6d677..1dc2633 100755
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -38,25 +38,18 @@ static GLuint prog;
 #define VERTEX_SLOT 0
 
 static GLuint sampler_slot;
-static GLuint width_slot;
-static GLuint height_slot;
 
 static void
 Redisplay()
 {
 	Scene::Render();
 
-	int viewport[4];
-	glGetIntegerv(GL_VIEWPORT, viewport);
-
 	glClear(GL_COLOR_BUFFER_BIT);
 
 	glUseProgram(prog);
 	glBindTexture(GL_TEXTURE_2D, Scene::fbo_tex);
 
 	glUniform1i(sampler_slot, 0);
-	glUniform1f(width_slot, float(viewport[2]));
-	glUniform1f(height_slot, float(viewport[3]));
 
 	GLfloat quad[4][2] = {{-1, 1}, {-1, -1}, {1, 1}, {1, -1}};
 
@@ -87,8 +80,6 @@ setup_shader()
 		exit(-1);
 
 	sampler_slot = glGetUniformLocation(prog, "sampler");
-	width_slot = glGetUniformLocation(prog, "width");
-	height_slot = glGetUniformLocation(prog, "height");
 }
 
 
diff --git a/src/sobel.frag b/src/sobel.frag
index 9d329f7..dd07bf5 100644
--- a/src/sobel.frag
+++ b/src/sobel.frag
@@ -1,27 +1,20 @@
-#version 120
+#version 130
 
-varying vec2 texcoord;
+in vec2 texcoord;
 uniform sampler2D sampler;
 
-uniform float width;
-uniform float height;
-
-// Texel offsets
-float off_x = 1/width;
-float off_y = 1/height;
-
 void main(void)
 {
 	// http://www.roborealm.com/help/Sobel.php
-	vec4 p1 = texture2D(sampler, texcoord - off_x - off_y);
-	vec4 p2 = texture2D(sampler, texcoord         - off_y);
-	vec4 p3 = texture2D(sampler, texcoord + off_x - off_y);
-	vec4 p4 = texture2D(sampler, texcoord - off_x        );
-	vec4 p5 = texture2D(sampler, texcoord                );
-	vec4 p6 = texture2D(sampler, texcoord + off_x        );
-	vec4 p7 = texture2D(sampler, texcoord - off_x + off_y);
-	vec4 p8 = texture2D(sampler, texcoord         + off_y);
-	vec4 p9 = texture2D(sampler, texcoord + off_x + off_y);
+	vec4 p1 = textureOffset(sampler, texcoord, ivec2(-1, -1));
+	vec4 p2 = textureOffset(sampler, texcoord, ivec2( 0, -1));
+	vec4 p3 = textureOffset(sampler, texcoord, ivec2( 1, -1));
+	vec4 p4 = textureOffset(sampler, texcoord, ivec2(-1,  0));
+	vec4 p5 = textureOffset(sampler, texcoord, ivec2( 0,  0));
+	vec4 p6 = textureOffset(sampler, texcoord, ivec2( 1,  0));
+	vec4 p7 = textureOffset(sampler, texcoord, ivec2(-1,  1));
+	vec4 p8 = textureOffset(sampler, texcoord, ivec2( 0,  1));
+	vec4 p9 = textureOffset(sampler, texcoord, ivec2( 1,  1));
 
 	vec4 Gx = p1+2*p2+p3-p7-2*p8-p9;
 	vec4 Gy = p3+2*p6+p9-p1-2*p4-p7;
diff --git a/src/sobel.vert b/src/sobel.vert
index 2bbcbe4..99ca619 100644
--- a/src/sobel.vert
+++ b/src/sobel.vert
@@ -1,7 +1,7 @@
-#version 120
+#version 130
 
-attribute vec2 vertex;
-varying vec2 texcoord;
+in vec2 vertex;
+out vec2 texcoord;
 
 void main(void)
 {
-- 
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