114 lines
3.2 KiB
GLSL
114 lines
3.2 KiB
GLSL
[vertex]
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layout(location=0) in highp vec4 vertex_attrib;
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void main() {
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gl_Position = vertex_attrib;
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gl_Position.z=1.0;
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}
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[fragment]
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uniform sampler2D source_ssao; //texunit:0
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uniform sampler2D source_depth; //texunit:1
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layout(location = 0) out float visibility;
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//////////////////////////////////////////////////////////////////////////////////////////////
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// Tunable Parameters:
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/** Increase to make depth edges crisper. Decrease to reduce flicker. */
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#define EDGE_SHARPNESS (1.0)
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/** Step in 2-pixel intervals since we already blurred against neighbors in the
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first AO pass. This constant can be increased while R decreases to improve
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performance at the expense of some dithering artifacts.
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Morgan found that a scale of 3 left a 1-pixel checkerboard grid that was
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unobjectionable after shading was applied but eliminated most temporal incoherence
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from using small numbers of sample taps.
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*/
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#define SCALE (3)
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/** Filter radius in pixels. This will be multiplied by SCALE. */
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#define R (4)
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//////////////////////////////////////////////////////////////////////////////////////////////
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// Gaussian coefficients
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const float gaussian[R + 1] =
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// float[](0.356642, 0.239400, 0.072410, 0.009869);
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// float[](0.398943, 0.241971, 0.053991, 0.004432, 0.000134); // stddev = 1.0
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float[](0.153170, 0.144893, 0.122649, 0.092902, 0.062970); // stddev = 2.0
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// float[](0.111220, 0.107798, 0.098151, 0.083953, 0.067458, 0.050920, 0.036108); // stddev = 3.0
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/** (1, 0) or (0, 1)*/
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uniform ivec2 axis;
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uniform float camera_z_far;
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uniform float camera_z_near;
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void main() {
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ivec2 ssC = ivec2(gl_FragCoord.xy);
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float depth = texelFetch(source_depth, ssC, 0).r;
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depth = depth * 2.0 - 1.0;
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depth = 2.0 * camera_z_near * camera_z_far / (camera_z_far + camera_z_near - depth * (camera_z_far - camera_z_near));
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float depth_divide = 1.0 / camera_z_far;
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depth*=depth_divide;
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//if (depth > camera_z_far*0.999) {
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// discard;//skybox
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//}
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float sum = texelFetch(source_ssao, ssC, 0).r;
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// Base weight for depth falloff. Increase this for more blurriness,
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// decrease it for better edge discrimination
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float BASE = gaussian[0];
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float totalWeight = BASE;
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sum *= totalWeight;
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for (int r = -R; r <= R; ++r) {
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// We already handled the zero case above. This loop should be unrolled and the static branch optimized out,
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// so the IF statement has no runtime cost
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if (r != 0) {
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ivec2 ppos = ssC + axis * (r * SCALE);
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float value = texelFetch(source_ssao, ppos, 0).r;
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float temp_depth = texelFetch(source_depth, ssC, 0).r;
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temp_depth = temp_depth * 2.0 - 1.0;
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temp_depth = 2.0 * camera_z_near * camera_z_far / (camera_z_far + camera_z_near - temp_depth * (camera_z_far - camera_z_near));
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temp_depth *= depth_divide;
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// spatial domain: offset gaussian tap
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float weight = 0.3 + gaussian[abs(r)];
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// range domain (the "bilateral" weight). As depth difference increases, decrease weight.
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weight *= max(0.0, 1.0
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- (EDGE_SHARPNESS * 2000.0) * abs(temp_depth - depth)
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);
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sum += value * weight;
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totalWeight += weight;
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}
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}
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const float epsilon = 0.0001;
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visibility = sum / (totalWeight + epsilon);
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}
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