X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=dither_effect.cpp;h=3fa6aebc3fa8f674674ca37e37ac6932be78c6fe;hp=cdfb157e675900a08ed3a859889641e01df7ba4a;hb=34776d3ed2565ee834405e575bf3bfc7f7933e36;hpb=ff9e68a3f5abb179bd7bf9fb84df48327f148583

diff --git a/dither_effect.cpp b/dither_effect.cpp
index cdfb157..3fa6aeb 100644
--- a/dither_effect.cpp
+++ b/dither_effect.cpp
@@ -1,9 +1,16 @@
-#include <math.h>
+#include <epoxy/gl.h>
 #include <assert.h>
+#include <stdio.h>
+#include <algorithm>
 
 #include "dither_effect.h"
+#include "effect_util.h"
+#include "init.h"
 #include "util.h"
-#include "opengl.h"
+
+using namespace std;
+
+namespace movit {
 
 namespace {
 
@@ -28,6 +35,10 @@ DitherEffect::DitherEffect()
 	register_int("output_width", &width);
 	register_int("output_height", &height);
 	register_int("num_bits", &num_bits);
+	register_uniform_float("round_fac", &uniform_round_fac);
+	register_uniform_float("inv_round_fac", &uniform_inv_round_fac);
+	register_uniform_vec2("tc_scale", uniform_tc_scale);
+	register_uniform_sampler2d("dither_tex", &uniform_dither_tex);
 
 	glGenTextures(1, &texnum);
 }
@@ -37,21 +48,29 @@ DitherEffect::~DitherEffect()
 	glDeleteTextures(1, &texnum);
 }
 
-std::string DitherEffect::output_fragment_shader()
+string DitherEffect::output_fragment_shader()
 {
-	return read_file("dither_effect.frag");
+	char buf[256];
+	sprintf(buf, "#define NEED_EXPLICIT_ROUND %d\n", (movit_num_wrongly_rounded > 0));
+	return buf + read_file("dither_effect.frag");
 }
 
-void DitherEffect::update_texture(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num)
+void DitherEffect::update_texture(GLuint glsl_program_num, const string &prefix, unsigned *sampler_num)
 {
 	float *dither_noise = new float[width * height];
 	float dither_double_amplitude = 1.0f / (1 << num_bits);
 
+	// We don't need a strictly nonrepeating dither; reducing the resolution
+	// to max 128x128 saves a lot of texture bandwidth, without causing any
+	// noticeable harm to the dither's performance.
+	texture_width = min(width, 128);
+	texture_height = min(height, 128);
+
 	// Using the resolution as a seed gives us a consistent dither from frame to frame.
 	// It also gives a different dither for e.g. different aspect ratios, which _feels_
 	// good, but probably shouldn't matter.
 	unsigned seed = (width << 16) ^ height;
-	for (int i = 0; i < width * height; ++i) {
+	for (int i = 0; i < texture_width * texture_height; ++i) {
 		seed = lcg_rand(seed);
 		float normalized_rand = seed * (1.0f / (1U << 31)) - 0.5;  // [-0.5, 0.5>
 		dither_noise[i] = dither_double_amplitude * normalized_rand;
@@ -63,20 +82,26 @@ void DitherEffect::update_texture(GLuint glsl_program_num, const std::string &pr
 	check_error();
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 	check_error();
-	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+	check_error();
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
 	check_error();
-	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
 	check_error();
-	glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE16F_ARB, width, height, 0, GL_LUMINANCE, GL_FLOAT, dither_noise);
+	glTexImage2D(GL_TEXTURE_2D, 0, GL_R16F, texture_width, texture_height, 0, GL_RED, GL_FLOAT, dither_noise);
 	check_error();
 
 	delete[] dither_noise;
 }
 
-void DitherEffect::set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num)
+void DitherEffect::set_gl_state(GLuint glsl_program_num, const string &prefix, unsigned *sampler_num)
 {
 	Effect::set_gl_state(glsl_program_num, prefix, sampler_num);
 
+	assert(width > 0);
+	assert(height > 0);
+	assert(num_bits > 0);
+
 	if (width != last_width || height != last_height || num_bits != last_num_bits) {
 		update_texture(glsl_program_num, prefix, sampler_num);
 		last_width = width;
@@ -89,6 +114,19 @@ void DitherEffect::set_gl_state(GLuint glsl_program_num, const std::string &pref
 	glBindTexture(GL_TEXTURE_2D, texnum);
 	check_error();
 
-	set_uniform_int(glsl_program_num, prefix, "dither_tex", *sampler_num);
-	++sampler_num;
+	uniform_dither_tex = *sampler_num;
+	++*sampler_num;
+
+	// In theory, we should adjust for the texel centers that have moved here as well,
+	// but since we use GL_NEAREST and we don't really care a lot what texel we sample,
+	// we don't have to worry about it.	
+	uniform_tc_scale[0] = float(width) / float(texture_width);
+	uniform_tc_scale[1] = float(height) / float(texture_height);
+
+	// Used if the shader needs to do explicit rounding.
+	int round_fac = (1 << num_bits) - 1;
+	uniform_round_fac = round_fac;
+	uniform_inv_round_fac = 1.0f / round_fac;
 }
+
+}  // namespace movit