How to manually create bilinear interpolation in HLSL using Gather functions?? I am trying to create a bilinear interpolation filter using HLSL and the GatherRed / GatherGreen / GatherBlue functions but I am getting really poor results compared to a proper hardware bilinear filter as you can see in the image attached to this post. Here is the pixel shader code I am using: Texture2D g_texture : register(t0); struct pixel_in { float2 tex_coord : TEXCOORD; }; float3 bilinear(float2 texcoord, float tex_dimension) { float3 result; // red channel float4 reds = g_texture.GatherRed(g_sampler, texcoord); float r1 = reds.x; float r2 = reds.y; float r3 = reds.z; float r4 = reds.w; float2 fract = frac(texcoord.xy * tex_dimension); float top_row_red = lerp(r1, r2, fract.x); float bottom_row_red = lerp(r3, r4, fract.x); float final_red = lerp(bottom_row_red, top_row_red, fract.y); result.x = final_red; // green channel float4 greens = g_texture.GatherGreen(g_sampler, texcoord); float g1 = greens.x; float g2 = greens.y; float g3 = greens.z; float g4 = greens.w; float top_row_green = lerp(g1, g2, fract.x); float bottom_row_green = lerp(g3, g4, fract.x); float final_green = lerp(bottom_row_green, top_row_green, fract.y); result.y = final_green; // blue channel float4 blues = g_texture.GatherBlue(g_sampler, texcoord); float b1 = blues.x; float b2 = blues.y; float b3 = blues.z; float b4 = blues.w; float top_row_blue = lerp(b1, b2, fract.x); float bottom_row_blue = lerp(b3, b4, fract.x); float final_blue = lerp(bottom_row_blue, top_row_blue, fract.y); result.z = final_blue; return result; } float4 PS(pixel_input pin) : SV_Target { uint width_texels; uint height_texels; g_texture.GetDimensions(width_texels, height_texels); float4 result = float4(0.0f, 0.0f, 0.0f, 1.0f); result.xyz = bilinear(pin.tex_coord, width_texels); return result; } I'm really not sure what I'm doing wrong here, there doesn't seem to be much linear interpolation hapening in my version but I'm not sure why. https://ift.tt/eA8V8J

I am trying to create a bilinear interpolation filter using HLSL and the GatherRed / GatherGreen / GatherBlue functions but I am getting really poor results compared to a proper hardware bilinear filter as you can see in the image attached to this post. Here is the pixel shader code I am using: Texture2D g_texture : register(t0); struct pixel_in { float2 tex_coord : TEXCOORD; }; float3 bilinear(float2 texcoord, float tex_dimension) { float3 result; // red channel float4 reds = g_texture.GatherRed(g_sampler, texcoord); float r1 = reds.x; float r2 = reds.y; float r3 = reds.z; float r4 = reds.w; float2 fract = frac(texcoord.xy * tex_dimension); float top_row_red = lerp(r1, r2, fract.x); float bottom_row_red = lerp(r3, r4, fract.x); float final_red = lerp(bottom_row_red, top_row_red, fract.y); result.x = final_red; // green channel float4 greens = g_texture.GatherGreen(g_sampler, texcoord); float g1 = greens.x; float g2 = greens.y; float g3 = greens.z; float g4 = greens.w; float top_row_green = lerp(g1, g2, fract.x); float bottom_row_green = lerp(g3, g4, fract.x); float final_green = lerp(bottom_row_green, top_row_green, fract.y); result.y = final_green; // blue channel float4 blues = g_texture.GatherBlue(g_sampler, texcoord); float b1 = blues.x; float b2 = blues.y; float b3 = blues.z; float b4 = blues.w; float top_row_blue = lerp(b1, b2, fract.x); float bottom_row_blue = lerp(b3, b4, fract.x); float final_blue = lerp(bottom_row_blue, top_row_blue, fract.y); result.z = final_blue; return result; } float4 PS(pixel_input pin) : SV_Target { uint width_texels; uint height_texels; g_texture.GetDimensions(width_texels, height_texels); float4 result = float4(0.0f, 0.0f, 0.0f, 1.0f); result.xyz = bilinear(pin.tex_coord, width_texels); return result; } I'm really not sure what I'm doing wrong here, there doesn't seem to be much linear interpolation hapening in my version but I'm not sure why.

from GameDev.net https://ift.tt/2I2tQ4F