X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=padding_effect.cpp;h=a70025d015475f885a9841d96e40c08fe3ac762e;hp=2e428c4556d25bbec390fca0ad9a220e7362b86e;hb=7dca345804c7851ff09edcc7198c5def94b9c4b1;hpb=e2962f03fe8fb0b1c47be56eca26761da97453a0

diff --git a/padding_effect.cpp b/padding_effect.cpp
index 2e428c4..a70025d 100644
--- a/padding_effect.cpp
+++ b/padding_effect.cpp
@@ -1,36 +1,46 @@
-#include <math.h>
 #include <GL/glew.h>
+#include <assert.h>
 
+#include "effect_util.h"
 #include "padding_effect.h"
 #include "util.h"
 
+using namespace std;
+
+namespace movit {
+
 PaddingEffect::PaddingEffect()
 	: border_color(0.0f, 0.0f, 0.0f, 0.0f),
 	  output_width(1280),
 	  output_height(720),
 	  top(0),
-	  left(0)
+	  left(0),
+	  pad_from_bottom(0)
 {
 	register_vec4("border_color", (float *)&border_color);
 	register_int("width", &output_width);
 	register_int("height", &output_height);
 	register_float("top", &top);
 	register_float("left", &left);
+	register_int("pad_from_bottom", &pad_from_bottom);
 }
 
-std::string PaddingEffect::output_fragment_shader()
+string PaddingEffect::output_fragment_shader()
 {
 	return read_file("padding_effect.frag");
 }
 
-void PaddingEffect::set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num)
+void PaddingEffect::set_gl_state(GLuint glsl_program_num, const string &prefix, unsigned *sampler_num)
 {
 	Effect::set_gl_state(glsl_program_num, prefix, sampler_num);
 
-	float offset[2] = {
-		left / output_width,
-		(output_height - input_height - top) / output_height
-	};
+	float offset[2];
+	offset[0] = left / output_width;
+	if (pad_from_bottom) {
+		offset[1] = top / output_height;
+	} else {
+		offset[1] = (output_height - input_height - top) / output_height;
+	}
 	set_uniform_vec2(glsl_program_num, prefix, "offset", offset);
 
 	float scale[2] = {
@@ -63,12 +73,16 @@ void PaddingEffect::set_gl_state(GLuint glsl_program_num, const std::string &pre
 // differently in different modes.
 
 // 0.0 and 1.0 are interpreted the same, no matter the gamma ramp.
-// Alpha is not affected by gamma.
+// Alpha is not affected by gamma per se, but the combination of
+// premultiplied alpha and non-linear gamma curve does not make sense,
+// so if could possibly be converting blank alpha to non-blank
+// (ie., premultiplied), we need our output to be in linear light.
 bool PaddingEffect::needs_linear_light() const
 {
 	if ((border_color.r == 0.0 || border_color.r == 1.0) &&
 	    (border_color.g == 0.0 || border_color.g == 1.0) &&
-	    (border_color.b == 0.0 || border_color.b == 1.0)) {
+	    (border_color.b == 0.0 || border_color.b == 1.0) &&
+	    border_color.a == 1.0) {
 		return false;
 	}
 	return true;
@@ -89,20 +103,32 @@ bool PaddingEffect::needs_srgb_primaries() const
 	return true;
 }
 
-// If the border color is black, it doesn't matter if we're pre- or postmultiplied
-// (or even blank, as a hack). Otherwise, it does.
 Effect::AlphaHandling PaddingEffect::alpha_handling() const
 {
-	if (border_color.r == 0.0 && border_color.g == 0.0 && border_color.b == 0.0) {
+	// If the border color is black, it doesn't matter if we're pre- or postmultiplied.
+	// Note that for non-solid black (i.e. alpha < 1.0), we're equally fine with
+	// pre- and postmultiplied, but later effects might change this status
+	// (consider e.g. blur), so setting DONT_CARE_ALPHA_TYPE is inappropriate,
+	// as it propagate blank alpha through this effect.
+	if (border_color.r == 0.0 && border_color.g == 0.0 && border_color.b == 0.0 && border_color.a == 1.0) {
 		return DONT_CARE_ALPHA_TYPE;
 	}
-	return INPUT_AND_OUTPUT_ALPHA_PREMULTIPLIED;
+
+	// If the border color is solid, we preserve blank alpha, as we never output any
+	// new non-solid pixels.
+	if (border_color.a == 1.0) {
+		return INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK;
+	}
+
+	// Otherwise, we're going to output our border color in premultiplied alpha,
+	// so the other pixels better be premultiplied as well.
+	return INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA;
 }
 	
-void PaddingEffect::get_output_size(unsigned *width, unsigned *height) const
+void PaddingEffect::get_output_size(unsigned *width, unsigned *height, unsigned *virtual_width, unsigned *virtual_height) const
 {
-	*width = output_width;
-	*height = output_height;
+	*virtual_width = *width = output_width;
+	*virtual_height = *height = output_height;
 }
 	
 void PaddingEffect::inform_input_size(unsigned input_num, unsigned width, unsigned height)
@@ -111,3 +137,5 @@ void PaddingEffect::inform_input_size(unsigned input_num, unsigned width, unsign
 	input_width = width;
 	input_height = height;
 }
+
+}  // namespace movit