[opengl] prevent area from crashing nvlogl64.dll

Signed-off-by: lizzie <lizzie@eden-emu.dev>

src/video_core/host_shaders/present_area.frag

@@ -5,7 +5,6 @@ layout(location = 0) out vec4 color;
 layout(binding = 0) uniform sampler2D color_texture;
 
 #ifdef VULKAN
-
 struct ScreenRectVertex {
     vec2 position;
     vec2 tex_coord;
@@ -14,94 +13,79 @@ layout (push_constant) uniform PushConstants {
     mat4 modelview_matrix;
     ScreenRectVertex vertices[4];
 };
-
 #else // OpenGL
-
 layout(location = 1) uniform uvec2 screen_size;
-
 #endif
 
 /***** Area Sampling *****/
-
 // By Sam Belliveau and Filippo Tarpini. Public Domain license.
 // Effectively a more accurate sharp bilinear filter when upscaling,
 // that also works as a mathematically perfect downscale filter.
 // https://entropymine.com/imageworsener/pixelmixing/
 // https://github.com/obsproject/obs-studio/pull/1715
 // https://legacy.imagemagick.org/Usage/filter/
-vec4 AreaSampling(sampler2D textureSampler, vec2 texCoords, vec2 source_size, vec2 target_size) {
-    // Determine the sizes of the source and target images.
-    vec2 inverted_target_size = vec2(1.0) / target_size;
-
-    // Determine the range of the source image that the target pixel will cover.
-    vec2 range = source_size * inverted_target_size;
-    vec2 beg = (texCoords.xy * source_size) - (range * 0.5);
-    vec2 end = beg + range;
-
+vec4 AreaSampling(sampler2D s, vec2 tc, vec4 trans_bounds) {
     // Compute the top-left and bottom-right corners of the pixel box.
-    ivec2 f_beg = ivec2(floor(beg));
-    ivec2 f_end = ivec2(floor(end));
-
+    ivec4 b = ivec4(floor(trans_bounds));
     // Compute how much of the start and end pixels are covered horizontally & vertically.
-    float area_w = 1.0 - fract(beg.x);
-    float area_n = 1.0 - fract(beg.y);
-    float area_e = fract(end.x);
-    float area_s = fract(end.y);
-
+    // W,N,E,S
+    vec4 kb = vec4(1.0f - fract(trans_bounds.xy), fract(trans_bounds.zw));
     // Compute the areas of the corner pixels in the pixel box.
-    float area_nw = area_n * area_w;
-    float area_ne = area_n * area_e;
-    float area_sw = area_s * area_w;
-    float area_se = area_s * area_e;
-
-    // Initialize the color accumulator.
-    vec4 avg_color = vec4(0.0, 0.0, 0.0, 0.0);
-
-    // Accumulate corner pixels.
-    avg_color += area_nw * texelFetch(textureSampler, ivec2(f_beg.x, f_beg.y), 0);
-    avg_color += area_ne * texelFetch(textureSampler, ivec2(f_end.x, f_beg.y), 0);
-    avg_color += area_sw * texelFetch(textureSampler, ivec2(f_beg.x, f_end.y), 0);
-    avg_color += area_se * texelFetch(textureSampler, ivec2(f_end.x, f_end.y), 0);
+    // NW,NE,SW,SE
+    vec4 kc = kb.yyww * kb.xzxz;
+    // Accumulate corner pixels by forming a corner matrix.
+    vec4 r = mat4x4(
+        texelFetch(s, ivec2(b.xy), 0),
+        texelFetch(s, ivec2(b.zy), 0),
+        texelFetch(s, ivec2(b.xw), 0),
+        texelFetch(s, ivec2(b.zw), 0)
+    ) * kc;
 
     // Determine the size of the pixel box.
-    int x_range = int(f_end.x - f_beg.x - 0.5);
-    int y_range = int(f_end.y - f_beg.y - 0.5);
-
+    ivec2 q = clamp(ivec2(
+        int(b.z - b.x - 0.5f),
+        int(b.w - b.y - 0.5f)
+    ), ivec2(-16), ivec2(16));
+    vec2 qf = vec2(q);
     // Accumulate top and bottom edge pixels.
-    for (int x = f_beg.x + 1; x <= f_beg.x + x_range; ++x) {
-        avg_color += area_n * texelFetch(textureSampler, ivec2(x, f_beg.y), 0);
-        avg_color += area_s * texelFetch(textureSampler, ivec2(x, f_end.y), 0);
+    for (int x = 0; x < q.x; ++x) {
+        r += kb.y * texelFetch(s, ivec2(x + b.x + 1, b.y), 0);
+        r += kb.w * texelFetch(s, ivec2(x + b.x + 1, b.w), 0);
     }
-
     // Accumulate left and right edge pixels and all the pixels in between.
-    for (int y = f_beg.y + 1; y <= f_beg.y + y_range; ++y) {
-        avg_color += area_w * texelFetch(textureSampler, ivec2(f_beg.x, y), 0);
-        avg_color += area_e * texelFetch(textureSampler, ivec2(f_end.x, y), 0);
-
-        for (int x = f_beg.x + 1; x <= f_beg.x + x_range; ++x) {
-            avg_color += texelFetch(textureSampler, ivec2(x, y), 0);
+    for (int y = 0; y < q.y; ++y) {
+        r += kb.x * texelFetch(s, ivec2(b.x, y + b.y + 1), 0);
+        r += kb.z * texelFetch(s, ivec2(b.z, y + b.y + 1), 0);
+        for (int x = 0; x < q.x; ++x) {
+            r += texelFetch(s, ivec2(x, y) + b.xy + 1, 0);
         }
     }
-
     // Compute the area of the pixel box that was sampled.
-    float area_corners = area_nw + area_ne + area_sw + area_se;
-    float area_edges = float(x_range) * (area_n + area_s) + float(y_range) * (area_w + area_e);
-    float area_center = float(x_range) * float(y_range);
-
     // Return the normalized average color.
-    return avg_color / (area_corners + area_edges + area_center);
+    return r / (
+        kc.x + kc.y + kc.z + kc.w //corners
+        + qf.x * (kb.y + kb.w) + qf.y * (kb.x + kb.z) //edges
+        + qf.x * qf.y // center
+    );
 }
 
 void main() {
-    vec2 source_image_size = textureSize(color_texture, 0);
-    vec2 window_size;
-
-    #ifdef VULKAN
-    window_size.x = vertices[1].position.x - vertices[0].position.x;
-    window_size.y = vertices[2].position.y - vertices[0].position.y;
-    #else // OpenGL
-    window_size = screen_size;
-    #endif
+#ifdef VULKAN
+    vec2 dst_size = vec2(
+        vertices[1].position.x - vertices[0].position.x,
+        vertices[2].position.y - vertices[0].position.y
+    );
+#else // OpenGL
+    vec2 dst_size = screen_size;
+#endif
 
-    color = AreaSampling(color_texture, frag_tex_coord, source_image_size, window_size);
+    vec2 src_size = textureSize(color_texture, 0);
+    // Determine the range of the source image that the target pixel will cover.
+    vec2 scale = src_size * (1.0f / dst_size);
+    color = AreaSampling(color_texture, frag_tex_coord, vec4(
+        (frag_tex_coord * src_size) - (scale * 0.5f),
+        // (scale * 0.5f) + scale
+        // {A / 2 + A} ==> {(A + 2A) / 2} ==> {3A / 2} ==> {A * (3/2)}
+        (frag_tex_coord * src_size) + scale * 0.5f
+    ));
 }