Bugfix/macos pixelate mod (#97)

* Fixes issue with difference in fmod vs mod in GLSL/HLSL
* Moves pixelate origin check to video tick.

data/shaders/pixelate_circle.effect

@@ -1,3 +1,8 @@
+// Create MOD function that acts like glsl mod, rather than HLSL's fmod.
+// Necessary to have consistent pattern tiling in both OGL systems (mac/linux)
+// and DirectX systems (windows)
+#define MOD(x, y) (x - y * floor(x / y))
+
 uniform float4x4 ViewProj;
 uniform texture2d image;
 
@@ -30,15 +35,14 @@ VertData mainTransform(VertData v_in)
 
 float4 mainImage(VertData v_in) : TARGET
 {
-    // 1. Sample incoming pixel
+    // 1. Sample incoming pixel  
     float2 coord = v_in.uv * uv_size;
     float2 coord_p = coord - tess_origin; // Shifted box coordinate
     coord_p = float2(coord_p.x * cos_theta - coord_p.y * sin_theta, coord_p.x * sin_theta + coord_p.y * cos_theta);
-    float2 coord_grid = (coord_p - fmod(coord_p, pixel_size)) + sign(coord_p) *
-                           float2(pixel_size, pixel_size) / 2.0f;
-
-    float2 uv_prime = (float2(coord_grid.x * cos_rtheta - coord_grid.y * sin_rtheta, coord_grid.x * sin_rtheta + coord_grid.y * cos_rtheta) + tess_origin) / uv_size;
-    return distance(coord_grid, coord_p) <= pixel_size/2.0f ? image.Sample(textureSampler, uv_prime) : float4(0.0, 0.0, 0.0, 0.0);
+    float2 coord_grid = (coord_p - MOD(coord_p, pixel_size) + 
+                           float2(pixel_size, pixel_size) / 2.0f);
+    float2 uv_prime = (float2(coord_grid.x * cos_rtheta - coord_grid.y * sin_rtheta, coord_grid.x * sin_rtheta + coord_grid.y * cos_rtheta) + tess_origin)/uv_size;
+    return distance(coord_grid, coord_p) <= pixel_size/2.0f ? image.Sample(textureSampler, uv_prime) : float4(0.0f, 0.0f, 0.0f, 0.0f);
 }
 
 technique Draw

data/shaders/pixelate_square.effect

@@ -1,3 +1,8 @@
+// Create MOD function that acts like glsl mod, rather than HLSL's fmod.
+// Necessary to have consistent pattern tiling in both OGL systems (mac/linux)
+// and DirectX systems (windows)
+#define MOD(x, y) (x - y * floor(x / y))
+
 uniform float4x4 ViewProj;
 uniform texture2d image;
 
@@ -34,9 +39,8 @@ float4 mainImage(VertData v_in) : TARGET
     float2 coord = v_in.uv * uv_size;
     float2 coord_p = coord - tess_origin; // Shifted box coordinate
     coord_p = float2(coord_p.x * cos_theta - coord_p.y * sin_theta, coord_p.x * sin_theta + coord_p.y * cos_theta);
-    float2 coord_grid = (coord_p - fmod(coord_p, pixel_size) + sign(coord_p) *
+    float2 coord_grid = (coord_p - MOD(coord_p, pixel_size) + sign(coord_p) *
                            float2(pixel_size, pixel_size) / 2.0f);
-    //float2 uv_prime = (coord_grid + tess_origin) / uv_size;
     float2 uv_prime = (float2(coord_grid.x * cos_rtheta - coord_grid.y * sin_rtheta, coord_grid.x * sin_rtheta + coord_grid.y * cos_rtheta) + tess_origin)/uv_size;
     return image.Sample(textureSampler, uv_prime);
 }

src/obs-composite-blur-filter.c

@@ -282,15 +282,6 @@ static void composite_blur_update(void *data, obs_data_t *settings)
 {
 	struct composite_blur_filter_data *filter = data;
 
-	if (filter->width > 0 &&
-	    (float)obs_data_get_double(settings, "pixelate_origin_x") < -1.e8) {
-		double width = (double)obs_source_get_width(filter->context);
-		double height = (double)obs_source_get_height(filter->context);
-		obs_data_set_double(settings, "pixelate_origin_x", width / 2.0);
-		obs_data_set_double(settings, "pixelate_origin_y",
-				    height / 2.0);
-	}
-
 	filter->blur_algorithm =
 		(int)obs_data_get_int(settings, "blur_algorithm");
 
@@ -1731,11 +1722,24 @@ static void composite_blur_video_tick(void *data, float seconds)
 			dstr_free(&disable);
 		}
 	}
+	const uint32_t width = (uint32_t)obs_source_get_base_width(target);
+	const uint32_t height = (uint32_t)obs_source_get_base_height(target);
+	if(filter->width != width || filter->height != height) {
+		filter->width = (uint32_t)obs_source_get_base_width(target);
+		filter->height = (uint32_t)obs_source_get_base_height(target);
+		filter->uv_size.x = (float)filter->width;
+		filter->uv_size.y = (float)filter->height;
+		obs_data_t *settings = obs_source_get_settings(filter->context);
+		if (filter->width > 0 &&
+			(float)obs_data_get_double(settings, "pixelate_origin_x") < -1.e8) {
+				obs_data_set_double(settings, "pixelate_origin_x", (double)width / 2.0);
+				obs_data_set_double(settings, "pixelate_origin_y",
+						(double)height / 2.0);
+				filter->pixelate_tessel_center.x = (float)width / 2.0f;
+				filter->pixelate_tessel_center.y = (float)height / 2.0f;
+		}
+	}
 
-	filter->width = (uint32_t)obs_source_get_base_width(target);
-	filter->height = (uint32_t)obs_source_get_base_height(target);
-	filter->uv_size.x = (float)filter->width;
-	filter->uv_size.y = (float)filter->height;
 	filter->rendered = false;
 }