#include "blur_effect.h"
#include "util.h"
+// Must match blur_effect.frag.
+#define NUM_TAPS 16
+
BlurEffect::BlurEffect()
: radius(3.0f),
direction(HORIZONTAL)
{
Effect::set_uniforms(glsl_program_num, prefix, sampler_num);
- // We only have 15 taps to work with, and we want that to reach out to about 2.5*sigma.
- // Bump up the mipmap levels (giving us box blurs) until we have what we need.
+ int base_texture_size, texture_size;
+ if (direction == HORIZONTAL) {
+ base_texture_size = texture_size = 1280; // FIXME
+ } else if (direction == VERTICAL) {
+ base_texture_size = texture_size = 720; // FIXME
+ } else {
+ assert(false);
+ }
+
+ // We only have 16 taps to work with on each side, and we want that to
+ // reach out to about 2.5*sigma. Bump up the mipmap levels (giving us
+ // box blurs) until we have what we need.
+ //
+ // FIXME: we really need to pick the same mipmap level for both horizontal and vertical!
unsigned base_mipmap_level = 0;
float adjusted_radius = radius;
- float pixel_size = 1.0f;
- while (adjusted_radius * 2.5f > 7.0f) {
+ while (texture_size > 1 && adjusted_radius * 2.5f > NUM_TAPS / 2) {
++base_mipmap_level;
- adjusted_radius *= 0.5f;
- pixel_size *= 2.0f;
- }
+ texture_size /= 2; // Rounding down.
+ adjusted_radius = radius * float(texture_size) / float(base_texture_size);
+ }
// In the second pass, we do the same, but don't sample from a mipmap;
// that would re-blur the other direction in an ugly fashion, and we already
}
glActiveTexture(GL_TEXTURE0);
+ check_error();
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, base_mipmap_level);
check_error();
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, base_mipmap_level);
+ check_error();
- // FIXME
- if (direction == HORIZONTAL) {
- float ps[] = { pixel_size / 1280.0f, 0.0f };
- set_uniform_vec2(glsl_program_num, prefix, "pixel_offset", ps);
- } else if (direction == VERTICAL) {
- float ps[] = { 0.0f, pixel_size / 720.0f };
- set_uniform_vec2(glsl_program_num, prefix, "pixel_offset", ps);
+ // Compute the weights; they will be symmetrical, so we only compute
+ // the right side.
+ float weight[NUM_TAPS + 1];
+ if (radius < 1e-3) {
+ weight[0] = 1.0f;
+ for (unsigned i = 1; i < NUM_TAPS + 1; ++i) {
+ weight[i] = 0.0f;
+ }
} else {
- assert(false);
+ float sum = 0.0f;
+ for (unsigned i = 0; i < NUM_TAPS + 1; ++i) {
+ float z = i / adjusted_radius;
+
+ // Gaussian blur is a common, but maybe not the prettiest choice;
+ // it can feel a bit too blurry in the fine detail and too little
+ // long-tail. This is a simple logistic distribution, which has
+ // a narrower peak but longer tails.
+ weight[i] = 1.0f / (cosh(z) * cosh(z));
+
+ if (i == 0) {
+ sum += weight[i];
+ } else {
+ sum += 2.0f * weight[i];
+ }
+ }
+ for (unsigned i = 0; i < NUM_TAPS + 1; ++i) {
+ weight[i] /= sum;
+ }
}
- // Simple Gaussian weights for now.
- float weight[15], total = 0.0f;
- for (unsigned i = 0; i < 15; ++i) {
- float z = (i - 7.0f) / adjusted_radius;
- weight[i] = exp(-(z*z));
- total += weight[i];
+#if 0
+ // NOTE: This is currently broken.
+
+ // Since the GPU gives us bilinear sampling for free, we can get two
+ // samples for the price of one (for every but the center sample,
+ // in which case this trick doesn't buy us anything). Simply sample
+ // between the two pixel centers, and we can do with fewer weights.
+ // (This is right even in the vertical pass where we don't actually
+ // sample between the pixels, because we have linear interpolation
+ // there too.)
+ //
+ // We pack the parameters into a float4: The relative sample coordinates
+ // in (x,y), and the weight in z. w is unused.
+ float samples[4 * (NUM_TAPS / 2 + 1)];
+
+ // Center sample.
+ samples[4 * 0 + 0] = 0.0f;
+ samples[4 * 0 + 1] = 0.0f;
+ samples[4 * 0 + 2] = weight[0];
+ samples[4 * 0 + 3] = 0.0f;
+
+ // All other samples.
+ for (unsigned i = 1; i < NUM_TAPS / 2 + 1; ++i) {
+ unsigned base_pos = i * 2 - 1;
+ float w1 = weight[base_pos];
+ float w2 = weight[base_pos + 1];
+
+ float offset, total_weight;
+ if (w1 + w2 < 1e-6) {
+ offset = 0.5f;
+ total_weight = 0.0f;
+ } else {
+ offset = w2 / (w1 + w2);
+ total_weight = w1 + w2;
+ }
+#if 0
+ // hack for easier visualization
+ offset = 0.5f;
+ total_weight = 8.0f;
+#endif
+ float x = 0.0f, y = 0.0f;
+
+ if (direction == HORIZONTAL) {
+ x = (base_pos + offset) / (float)texture_size;
+ } else if (direction == VERTICAL) {
+ y = (base_pos + offset) / (float)texture_size;
+ } else {
+ assert(false);
+ }
+
+ samples[4 * i + 0] = x;
+ samples[4 * i + 1] = y;
+ samples[4 * i + 2] = total_weight;
+ samples[4 * i + 3] = 0.0f;
}
- printf("[mip level %d] ", base_mipmap_level);
- for (unsigned i = 0; i < 15; ++i) {
- weight[i] /= total;
- printf("%f ", weight[i]);
+
+ set_uniform_vec4_array(glsl_program_num, prefix, "samples", samples, NUM_TAPS / 2 + 1);
+#else
+ // Boring, at-whole-pixels sampling.
+ float samples[4 * NUM_TAPS];
+
+ // All other samples.
+ for (unsigned i = 0; i < NUM_TAPS + 1; ++i) {
+ float x = 0.0f, y = 0.0f;
+
+ if (direction == HORIZONTAL) {
+ x = i / (float)texture_size;
+ } else if (direction == VERTICAL) {
+ y = i / (float)texture_size;
+ } else {
+ assert(false);
+ }
+
+ samples[4 * i + 0] = x;
+ samples[4 * i + 1] = y;
+ samples[4 * i + 2] = weight[i];
+ samples[4 * i + 3] = 0.0f;
}
- printf("\n");
- set_uniform_float_array(glsl_program_num, prefix, "weight", weight, 15);
+
+ set_uniform_vec4_array(glsl_program_num, prefix, "samples", samples, NUM_TAPS + 1);
+#endif
}
// A simple unidirectional blur.
-uniform vec2 PREFIX(pixel_offset);
-uniform float PREFIX(weight)[15];
+#define NUM_TAPS 16
+
+uniform vec4 PREFIX(samples)[NUM_TAPS + 1];
vec4 FUNCNAME(vec2 tc) {
- vec4 x = LAST_INPUT(tc);
- return
- vec4(PREFIX(weight)[ 0]) * LAST_INPUT(tc - 7.0 * PREFIX(pixel_offset)) +
- vec4(PREFIX(weight)[ 1]) * LAST_INPUT(tc - 6.0 * PREFIX(pixel_offset)) +
- vec4(PREFIX(weight)[ 2]) * LAST_INPUT(tc - 5.0 * PREFIX(pixel_offset)) +
- vec4(PREFIX(weight)[ 3]) * LAST_INPUT(tc - 4.0 * PREFIX(pixel_offset)) +
- vec4(PREFIX(weight)[ 4]) * LAST_INPUT(tc - 3.0 * PREFIX(pixel_offset)) +
- vec4(PREFIX(weight)[ 5]) * LAST_INPUT(tc - 2.0 * PREFIX(pixel_offset)) +
- vec4(PREFIX(weight)[ 6]) * LAST_INPUT(tc - PREFIX(pixel_offset)) +
- vec4(PREFIX(weight)[ 7]) * LAST_INPUT(tc) +
- vec4(PREFIX(weight)[ 8]) * LAST_INPUT(tc + PREFIX(pixel_offset)) +
- vec4(PREFIX(weight)[ 9]) * LAST_INPUT(tc + 2.0 * PREFIX(pixel_offset)) +
- vec4(PREFIX(weight)[10]) * LAST_INPUT(tc + 3.0 * PREFIX(pixel_offset)) +
- vec4(PREFIX(weight)[11]) * LAST_INPUT(tc + 4.0 * PREFIX(pixel_offset)) +
- vec4(PREFIX(weight)[12]) * LAST_INPUT(tc + 5.0 * PREFIX(pixel_offset)) +
- vec4(PREFIX(weight)[13]) * LAST_INPUT(tc + 6.0 * PREFIX(pixel_offset)) +
- vec4(PREFIX(weight)[14]) * LAST_INPUT(tc + 7.0 * PREFIX(pixel_offset));
+ vec4 sum = vec4(PREFIX(samples)[0].z) * LAST_INPUT(tc);
+ for (int i = 1; i < NUM_TAPS + 1; ++i) {
+ vec4 sample = PREFIX(samples)[i];
+ sum += vec4(sample.z) * (LAST_INPUT(tc - sample.xy) + LAST_INPUT(tc + sample.xy));
+ }
+ return sum;
}
projects / movit / commitdiff