[vlc-devel] [PATCH 3/4] direct3d11: switch the pixel shader to point interpolation when reaching visible sides

[Steve Lhomme]

The texture is bigger than the visible sides, so if we use linear interpolation
on the last pixel it will use values with unknown values on the part where it
would do clamping otherwise. So we force it to use point interpolation (not
using pixels around) for the last line/column to display.
---
 modules/video_output/win32/direct3d11.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/modules/video_output/win32/direct3d11.c b/modules/video_output/win32/direct3d11.c
index ecf76fdfe6..0793db9477 100644
--- a/modules/video_output/win32/direct3d11.c
+++ b/modules/video_output/win32/direct3d11.c
@@ -186,7 +186,9 @@ typedef struct d3d_vertex_t {
 
 typedef struct {
     FLOAT Opacity;
-    FLOAT opacityPadding[3];
+    FLOAT BoundaryX;
+    FLOAT BoundaryY;
+    FLOAT padding;
 } PS_CONSTANT_BUFFER;
 
 typedef struct {
@@ -305,7 +307,9 @@ static const char* globPixelShaderDefault = "\
   cbuffer PS_CONSTANT_BUFFER : register(b0)\
   {\
     float Opacity;\
-    float opacityPadding[3];\
+    float BoundaryX;\
+    float BoundaryY;\
+    float padding;\
   };\
   cbuffer PS_COLOR_TRANSFORM : register(b1)\
   {\
@@ -377,7 +381,10 @@ static const char* globPixelShaderDefault = "\
   {\
     float4 sample;\
     \
-    sample = sampleTexture( SamplerStates[0], In.Texture );\
+    if (In.Texture.x > BoundaryX || In.Texture.y > BoundaryY) \
+        sample = sampleTexture( SamplerStates[1], In.Texture );\
+    else\
+        sample = sampleTexture( SamplerStates[0], In.Texture );\
     float4 rgba = mul(mul(sample, WhitePoint), Colorspace);\
     float opacity = rgba.a * Opacity;\
     float3 rgb = (float3)rgba;\
@@ -2535,9 +2542,16 @@ static int SetupQuad(vout_display_t *vd, const video_format_t *fmt, d3d_quad_t *
     const bool RGB_shader = IsRGBShader(cfg);
 
     /* pixel shader constant buffer */
-    PS_CONSTANT_BUFFER defaultConstants = {
-      .Opacity = 1,
-    };
+    PS_CONSTANT_BUFFER defaultConstants;
+    defaultConstants.Opacity = 1.0;
+    if (fmt->i_visible_width == fmt->i_width)
+        defaultConstants.BoundaryX = 1.0; /* let texture clamping happen */
+    else
+        defaultConstants.BoundaryX = (FLOAT) (fmt->i_visible_width - 1) / fmt->i_width;
+    if (fmt->i_visible_height == fmt->i_height)
+        defaultConstants.BoundaryY = 1.0; /* let texture clamping happen */
+    else
+        defaultConstants.BoundaryY = (FLOAT) (fmt->i_visible_height - 1) / fmt->i_height;
     static_assert((sizeof(PS_CONSTANT_BUFFER)%16)==0,"Constant buffers require 16-byte alignment");
     D3D11_BUFFER_DESC constantDesc = {
         .Usage = D3D11_USAGE_DYNAMIC,
-- 
2.14.2