X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=motion_search.vert;h=d0232767fbcef03434d18ad532ffbc0e0bbf870d;hb=3795723be95f2fe82f3c8b8b45b1a905b2c811fd;hp=dbb27956814ed3438b892dc9ed95256587746ebc;hpb=d51c933ab4f9cbd90b4c5577d5d9ed5d89afefb4;p=nageru

diff --git a/motion_search.vert b/motion_search.vert
index dbb2795..d023276 100644
--- a/motion_search.vert
+++ b/motion_search.vert
@@ -1,13 +1,35 @@
 #version 450 core
+#extension GL_ARB_shader_viewport_layer_array : require
 
-in vec2 position;
-out vec2 flow_tc;
-out vec2 patch_bottom_left_texel;  // Center of bottom-left texel of patch.
+layout(location=0) in vec2 position;
+out vec3 flow_tc;
+out vec2 patch_center;
+flat out int ref_layer, search_layer;
 
-uniform vec2 inv_flow_size, inv_image_size;
+uniform sampler2DArray flow_tex;
+uniform vec2 out_flow_size;
 
 void main()
 {
+	// Patch placement: We want the outermost patches to have centers exactly in the
+	// image corners, so that the bottom-left patch has centre (0,0) and the
+	// upper-right patch has center (1,1). The position we get in is _almost_ there;
+	// since the quad's corners are in (0,0) and (1,1), the fragment shader will get
+	// centers in x=0.5/w, x=1.5/w and so on (and similar for y).
+	//
+	// In other words, find some f(x) = ax + b so that
+	//
+	//   a 0.5 / w + b = 0
+	//   a (1.0 - 0.5 / w) + b = 1
+	//
+	// which gives
+	//
+	//   a = 1 / (w - 1)
+	//   b = w / 2 (w - 1)
+	vec2 a = out_flow_size / (out_flow_size - 1);
+	vec2 b = -1.0 / (2 * (out_flow_size - 1.0));
+	patch_center = a * position + b;
+
 	// The result of glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, 1.0) is:
 	//
 	//   2.000  0.000  0.000 -1.000
@@ -15,8 +37,11 @@ void main()
 	//   0.000  0.000 -2.000 -1.000
 	//   0.000  0.000  0.000  1.000
 	gl_Position = vec4(2.0 * position.x - 1.0, 2.0 * position.y - 1.0, -1.0, 1.0);
-	flow_tc = position;
+	flow_tc = vec3(position, gl_InstanceID);
+
+	gl_Layer = gl_InstanceID;
 
-	vec2 patch_bottom_left = position - vec2(0.5, 0.5) * inv_flow_size;
-	patch_bottom_left_texel = patch_bottom_left + vec2(0.5, 0.5) * inv_image_size;
+	// Forward flow (0) goes from 0 to 1. Backward flow (1) goes from 1 to 0.
+	ref_layer = gl_InstanceID;
+	search_layer = 1 - gl_InstanceID;
 }