X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=fft_pass_effect.cpp;h=ee0b983ae92002875d5b8e86538e21b09846991b;hp=695a763f0b14f79cd119e527737ff8c4a382e7bc;hb=67b2debafd624d3be66588171d6ec677b54247ba;hpb=12c11c0e615f7fc17ef7a600ff0c9099f7908dbc

diff --git a/fft_pass_effect.cpp b/fft_pass_effect.cpp
index 695a763..ee0b983 100644
--- a/fft_pass_effect.cpp
+++ b/fft_pass_effect.cpp
@@ -1,7 +1,9 @@
 #include <epoxy/gl.h>
 #include <math.h>
 
+#include "effect_chain.h"
 #include "effect_util.h"
+#include "fp16.h"
 #include "fft_pass_effect.h"
 #include "util.h"
 
@@ -39,15 +41,13 @@ void FFTPassEffect::set_gl_state(GLuint glsl_program_num, const string &prefix,
 
 	int input_size = (direction == VERTICAL) ? input_height : input_width;
 
-	// See the comments on changes_output_size() in the .h file to see
-	// why this is legal. It is _needed_ because it counteracts the
-	// precision issues we get because we sample the input texture with
-	// normalized coordinates (especially when the repeat count along
-	// the axis is not a power of two); we very rapidly end up in narrowly
-	// missing a texel center, which causes precision loss to propagate
-	// throughout the FFT.
-	assert(*sampler_num == 1);
-	glActiveTexture(GL_TEXTURE0);
+	// This is needed because it counteracts the precision issues we get
+	// because we sample the input texture with normalized coordinates
+	// (especially when the repeat count along the axis is not a power of
+	// two); we very rapidly end up in narrowly missing a texel center,
+	// which causes precision loss to propagate throughout the FFT.
+	Node *self = chain->find_node_for_effect(this);
+	glActiveTexture(chain->get_input_sampler(self, 0));
 	check_error();
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 	check_error();
@@ -79,7 +79,7 @@ void FFTPassEffect::set_gl_state(GLuint glsl_program_num, const string &prefix,
 	// bit, so the stride is 8, and so on.
 
 	assert((fft_size & (fft_size - 1)) == 0);  // Must be power of two.
-	float *tmp = new float[fft_size * 4];
+	fp16_int_t *tmp = new fp16_int_t[fft_size * 4];
 	int subfft_size = 1 << pass_number;
 	double mulfac;
 	if (inverse) {
@@ -117,17 +117,19 @@ void FFTPassEffect::set_gl_state(GLuint glsl_program_num, const string &prefix,
 		// is that we can have multiple FFTs along the same line,
 		// and want to reuse the support texture by repeating it.
 		int base = k * stride * 2 + offset;
-		int support_texture_index;
+		int support_texture_index = i;
+		int src1 = base;
+		int src2 = base + stride;
 		if (direction == FFTPassEffect::VERTICAL) {
 			// Compensate for OpenGL's bottom-left convention.
-			support_texture_index = fft_size - i - 1;
-		} else {
-			support_texture_index = i;
+			support_texture_index = fft_size - support_texture_index - 1;
+			src1 = fft_size - src1 - 1;
+			src2 = fft_size - src2 - 1;
 		}
-		tmp[support_texture_index * 4 + 0] = (base - support_texture_index) / double(input_size);
-		tmp[support_texture_index * 4 + 1] = (base + stride - support_texture_index) / double(input_size);
-		tmp[support_texture_index * 4 + 2] = twiddle_real;
-		tmp[support_texture_index * 4 + 3] = twiddle_imag;
+		tmp[support_texture_index * 4 + 0] = fp64_to_fp16((src1 - support_texture_index) / double(input_size));
+		tmp[support_texture_index * 4 + 1] = fp64_to_fp16((src2 - support_texture_index) / double(input_size));
+		tmp[support_texture_index * 4 + 2] = fp64_to_fp16(twiddle_real);
+		tmp[support_texture_index * 4 + 3] = fp64_to_fp16(twiddle_imag);
 	}
 
 	glActiveTexture(GL_TEXTURE0 + *sampler_num);
@@ -143,11 +145,14 @@ void FFTPassEffect::set_gl_state(GLuint glsl_program_num, const string &prefix,
 
 	// Supposedly FFTs are very sensitive to inaccuracies in the twiddle factors,
 	// at least according to a paper by Schatzman (see gpuwave.pdf reference [30]
-	// for the full reference), so we keep them at 32-bit. However, for
-	// small sizes, all components are exact anyway, so we can cheat there
-	// (although noting that the source coordinates become somewhat less
-	// accurate then, too).
-	glTexImage2D(GL_TEXTURE_2D, 0, (subfft_size <= 4) ? GL_RGBA16F : GL_RGBA32F, fft_size, 1, 0, GL_RGBA, GL_FLOAT, tmp);
+	// for the full reference); however, practical testing indicates that it's
+	// not a problem to keep the twiddle factors at 16-bit, at least as long as
+	// we round them properly--it would seem that Schatzman were mainly talking
+	// about poor sin()/cos() approximations. Thus, we store them in 16-bit,
+	// which gives a nice speed boost.
+	//
+	// Note that the source coordinates become somewhat less accurate too, though.
+	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, fft_size, 1, 0, GL_RGBA, GL_HALF_FLOAT, tmp);
 	check_error();
 
 	delete[] tmp;