GPU Pro 4

180 III Image Space

1.2.2 Blur Passes

The two blur passes are similar to one another. Each reads a fixed-length set of

adjacent samples, either horizontal or vertical, and computes two weighted sums.

The key outer loop section of the code is shown below.

// Accumulates the blurry image color

blurResult.rgb = float3 (0.0 f);

float blurWeightSum = 0.0f;

// Accumulates the near - field color and coverage

nearResult = float4 (0.0 f);

float nearWeightSum = 0.0f;

// Location of the central filter tap (i .e., "this" pixel ’s location )

// Account for the scaling down by 50% during blur

int2 A = int2 (gl_FragCoord.xy) * (direction + ivec2 (1));

float packedA = texelFetch( ...