Eevee: Depht Of Field: Merge Scatter passes together.

This means only one texture to draw to and only one sprite per pixel.

The texture is twice as large and near and far planes are side by side.

The sprite choose the biggest coc to expand to and is redirected to the
area (layer) it belongs to.

The fragment shader discard every pixel that does not belong to the correct
layer.

1 files changed, 19 insertions, 6 deletions

diff --git a/source/blender/draw/engines/eevee/shaders/effect_dof_vert.glsl b/source/blender/draw/engines/eevee/shaders/effect_dof_vert.glsl
index e28c957d58d..338003b92cd 100644
--- a/source/blender/draw/engines/eevee/shaders/effect_dof_vert.glsl
+++ b/source/blender/draw/engines/eevee/shaders/effect_dof_vert.glsl
@@ -1,17 +1,17 @@
 
-uniform vec2 layerSelection;
-
 uniform vec4 bokehParams[2];
 
 #define bokeh_rotation      bokehParams[0].x
 #define bokeh_ratio         bokehParams[0].y
 #define bokeh_maxsize       bokehParams[0].z
 
+uniform sampler2D nearBuffer;
+uniform sampler2D farBuffer;
 uniform sampler2D cocBuffer;
-uniform sampler2D colorBuffer;
 
 flat out vec4 color;
 flat out float smoothFac;
+flat out ivec2 edge;
 out vec2 particlecoord;
 
 #define M_PI 3.1415926535897932384626433832795
@@ -20,7 +20,9 @@ out vec2 particlecoord;
 void main()
 {
 	ivec2 tex_size = textureSize(cocBuffer, 0);
-	vec2 texel_size = 1.0 / vec2(tex_size);
+	/* We render to a double width texture so compute
+	 * the target texel size accordingly */
+	vec2 texel_size = vec2(0.5, 1.0) / vec2(tex_size);
 
 	int t_id = gl_VertexID / 3; /* Triangle Id */
 
@@ -30,16 +32,22 @@ void main()
 	texelco.y = t_id / tex_size.x;
 
 	vec2 cocs = texelFetch(cocBuffer, texelco, 0).rg;
-	float coc = dot(layerSelection, cocs);
+
+	bool is_near = (cocs.x > cocs.y);
+	float coc = (is_near) ? cocs.x : cocs.y;
 
 	/* Clamp to max size for performance */
 	coc = min(coc, bokeh_maxsize);
 
 	if (coc >= 1.0) {
-		color = texelFetch(colorBuffer, texelco, 0);
+		color = texelFetch((is_near) ? nearBuffer : farBuffer, texelco, 0);
 		/* find the area the pixel will cover and divide the color by it */
 		color.a = 1.0 / (coc * coc * M_PI);
 		color.rgb *= color.a;
+
+		/* Compute edge to discard fragment that does not belong to the other layer. */
+		edge.x = (is_near) ? 1 : -1;
+		edge.y = (is_near) ? -tex_size.x + 1 : tex_size.x;
 	}
 	else {
 		/* Don't produce any fragments */
@@ -78,6 +86,9 @@ void main()
 	gl_Position.xy -= 1.0 - 0.5 * texel_size; /* NDC Bottom left */
 	gl_Position.xy += (0.5 + vec2(texelco) * 2.0) * texel_size;
 
+	/* Push far plane to left side. */
+	gl_Position.x  += (!is_near) ? 1.0 : 0.0;
+
 	/* don't do smoothing for small sprites */
 	if (coc > 3.0) {
 		smoothFac = 1.0 - 1.5 / coc;
@@ -85,4 +96,6 @@ void main()
 	else {
 		smoothFac = 1.0;
 	}
+
+	int tex_width = textureSize(cocBuffer, 0).x;
 }