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Use Gaussian approximation for backbuffer mipmaps in GL Compatibility renderer #78168

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Jul 12, 2023
Merged

Use Gaussian approximation for backbuffer mipmaps in GL Compatibility renderer #78168

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76 changes: 76 additions & 0 deletions drivers/gles3/effects/copy_effects.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@
#ifdef GLES3_ENABLED

#include "copy_effects.h"
#include "../storage/texture_storage.h"

using namespace GLES3;

Expand Down Expand Up @@ -133,6 +134,7 @@ void CopyEffects::copy_screen() {
draw_screen_triangle();
}

// Intended for efficiently mipmapping textures.
void CopyEffects::bilinear_blur(GLuint p_source_texture, int p_mipmap_count, const Rect2i &p_region) {
GLuint framebuffers[2];
glGenFramebuffers(2, framebuffers);
Expand All @@ -158,6 +160,80 @@ void CopyEffects::bilinear_blur(GLuint p_source_texture, int p_mipmap_count, con
glDeleteFramebuffers(2, framebuffers);
}

// Intended for approximating a gaussian blur. Used for 2D backbuffer mipmaps. Slightly less efficient than bilinear_blur().
void CopyEffects::gaussian_blur(GLuint p_source_texture, int p_mipmap_count, const Rect2i &p_region, const Size2i &p_size) {
GLuint framebuffer;
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, p_source_texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

Size2i base_size = p_size;

Rect2i source_region = p_region;
Rect2i dest_region = p_region;

Size2 float_size = Size2(p_size);
Rect2 normalized_source_region = Rect2(p_region);
normalized_source_region.position = normalized_source_region.position / float_size;
normalized_source_region.size = normalized_source_region.size / float_size;
Rect2 normalized_dest_region = Rect2(p_region);
for (int i = 1; i < p_mipmap_count; i++) {
dest_region.position.x >>= 1;
dest_region.position.y >>= 1;
dest_region.size.x = MAX(1, dest_region.size.x >> 1);
dest_region.size.y = MAX(1, dest_region.size.y >> 1);
base_size.x >>= 1;
base_size.y >>= 1;

glBindTexture(GL_TEXTURE_2D, p_source_texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, i - 1);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, i - 1);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, p_source_texture, i);
#ifdef DEV_ENABLED
GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
if (status != GL_FRAMEBUFFER_COMPLETE) {
WARN_PRINT("Could not bind Gaussian blur framebuffer, status: " + GLES3::TextureStorage::get_singleton()->get_framebuffer_error(status));
}
#endif

glViewport(0, 0, base_size.x, base_size.y);

bool success = copy.shader.version_bind_shader(copy.shader_version, CopyShaderGLES3::MODE_GAUSSIAN_BLUR);
if (!success) {
return;
}

float_size = Size2(base_size);
normalized_dest_region.position = Size2(dest_region.position) / float_size;
normalized_dest_region.size = Size2(dest_region.size) / float_size;

copy.shader.version_set_uniform(CopyShaderGLES3::COPY_SECTION, normalized_dest_region.position.x, normalized_dest_region.position.y, normalized_dest_region.size.x, normalized_dest_region.size.y, copy.shader_version, CopyShaderGLES3::MODE_GAUSSIAN_BLUR);
copy.shader.version_set_uniform(CopyShaderGLES3::SOURCE_SECTION, normalized_source_region.position.x, normalized_source_region.position.y, normalized_source_region.size.x, normalized_source_region.size.y, copy.shader_version, CopyShaderGLES3::MODE_GAUSSIAN_BLUR);
copy.shader.version_set_uniform(CopyShaderGLES3::PIXEL_SIZE, 1.0 / float_size.x, 1.0 / float_size.y, copy.shader_version, CopyShaderGLES3::MODE_GAUSSIAN_BLUR);

draw_screen_quad();

source_region = dest_region;
normalized_source_region = normalized_dest_region;
}
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glDeleteFramebuffers(1, &framebuffer);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, p_mipmap_count - 1);
glBindTexture(GL_TEXTURE_2D, 0);

glViewport(0, 0, p_size.x, p_size.y);
}

void CopyEffects::set_color(const Color &p_color, const Rect2i &p_region) {
bool success = copy.shader.version_bind_shader(copy.shader_version, CopyShaderGLES3::MODE_SIMPLE_COLOR);
if (!success) {
Expand Down
1 change: 1 addition & 0 deletions drivers/gles3/effects/copy_effects.h
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Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,7 @@ class CopyEffects {
void copy_to_rect(const Rect2 &p_rect);
void copy_screen();
void bilinear_blur(GLuint p_source_texture, int p_mipmap_count, const Rect2i &p_region);
void gaussian_blur(GLuint p_source_texture, int p_mipmap_count, const Rect2i &p_region, const Size2i &p_size);
void set_color(const Color &p_color, const Rect2i &p_region);
void draw_screen_triangle();
void draw_screen_quad();
Expand Down
39 changes: 37 additions & 2 deletions drivers/gles3/shaders/copy.glsl
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Original file line number Diff line number Diff line change
Expand Up @@ -16,17 +16,24 @@ layout(location = 0) in vec2 vertex_attrib;
out vec2 uv_interp;
/* clang-format on */

#ifdef USE_COPY_SECTION
#if defined(USE_COPY_SECTION) || defined(MODE_GAUSSIAN_BLUR)
// Defined in 0-1 coords.
uniform highp vec4 copy_section;
#endif
#ifdef MODE_GAUSSIAN_BLUR
uniform highp vec4 source_section;
#endif

void main() {
uv_interp = vertex_attrib * 0.5 + 0.5;
gl_Position = vec4(vertex_attrib, 1.0, 1.0);

#ifdef USE_COPY_SECTION
#if defined(USE_COPY_SECTION) || defined(MODE_GAUSSIAN_BLUR)
gl_Position.xy = (copy_section.xy + uv_interp.xy * copy_section.zw) * 2.0 - 1.0;
#endif
#ifdef MODE_GAUSSIAN_BLUR
uv_interp = source_section.xy + uv_interp * source_section.zw;
#endif
}

/* clang-format off */
Expand All @@ -39,6 +46,7 @@ uniform vec4 color_in;
#endif

#ifdef MODE_GAUSSIAN_BLUR
// Defined in 0-1 coords.
uniform highp vec2 pixel_size;
#endif

Expand All @@ -55,4 +63,31 @@ void main() {
#ifdef MODE_SIMPLE_COLOR
frag_color = color_in;
#endif

// Efficient box filter from Jimenez: http://www.iryoku.com/next-generation-post-processing-in-call-of-duty-advanced-warfare
// Approximates a Gaussian in a single pass.
#ifdef MODE_GAUSSIAN_BLUR
vec4 A = textureLod(source, uv_interp + pixel_size * vec2(-1.0, -1.0), 0.0);
vec4 B = textureLod(source, uv_interp + pixel_size * vec2(0.0, -1.0), 0.0);
vec4 C = textureLod(source, uv_interp + pixel_size * vec2(1.0, -1.0), 0.0);
vec4 D = textureLod(source, uv_interp + pixel_size * vec2(-0.5, -0.5), 0.0);
vec4 E = textureLod(source, uv_interp + pixel_size * vec2(0.5, -0.5), 0.0);
vec4 F = textureLod(source, uv_interp + pixel_size * vec2(-1.0, 0.0), 0.0);
vec4 G = textureLod(source, uv_interp, 0.0);
vec4 H = textureLod(source, uv_interp + pixel_size * vec2(1.0, 0.0), 0.0);
vec4 I = textureLod(source, uv_interp + pixel_size * vec2(-0.5, 0.5), 0.0);
vec4 J = textureLod(source, uv_interp + pixel_size * vec2(0.5, 0.5), 0.0);
vec4 K = textureLod(source, uv_interp + pixel_size * vec2(-1.0, 1.0), 0.0);
vec4 L = textureLod(source, uv_interp + pixel_size * vec2(0.0, 1.0), 0.0);
vec4 M = textureLod(source, uv_interp + pixel_size * vec2(1.0, 1.0), 0.0);

float weight = 0.5 / 4.0;
float lesser_weight = 0.125 / 4.0;

frag_color = (D + E + I + J) * weight;
frag_color += (A + B + G + F) * lesser_weight;
frag_color += (B + C + H + G) * lesser_weight;
frag_color += (F + G + L + K) * lesser_weight;
frag_color += (G + H + M + L) * lesser_weight;
#endif
}
14 changes: 8 additions & 6 deletions drivers/gles3/storage/texture_storage.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1827,10 +1827,10 @@ void TextureStorage::_create_render_target_backbuffer(RenderTarget *rt) {
return;
}

// Initialize all levels to opaque Magenta.
// Initialize all levels to clear black.
for (int j = 0; j < count; j++) {
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, rt->backbuffer, j);
glClearColor(1.0, 0.0, 1.0, 1.0);
glClearColor(0.0, 0.0, 0.0, 0.0);
glClear(GL_COLOR_BUFFER_BIT);
}

Expand Down Expand Up @@ -2548,18 +2548,18 @@ void TextureStorage::render_target_copy_to_back_buffer(RID p_render_target, cons
}

glDisable(GL_BLEND);
//single texture copy for backbuffer
// Single texture copy for backbuffer.
glBindFramebuffer(GL_FRAMEBUFFER, rt->backbuffer_fbo);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, rt->color);
GLES3::CopyEffects::get_singleton()->copy_screen();

if (p_gen_mipmaps) {
GLES3::CopyEffects::get_singleton()->bilinear_blur(rt->backbuffer, rt->mipmap_count, region);
GLES3::CopyEffects::get_singleton()->gaussian_blur(rt->backbuffer, rt->mipmap_count, region, rt->size);
glBindFramebuffer(GL_FRAMEBUFFER, rt->backbuffer_fbo);
}

glEnable(GL_BLEND); // 2D almost always uses blend.
glEnable(GL_BLEND); // 2D starts with blend enabled.
}

void TextureStorage::render_target_clear_back_buffer(RID p_render_target, const Rect2i &p_region, const Color &p_color) {
Expand Down Expand Up @@ -2604,8 +2604,10 @@ void TextureStorage::render_target_gen_back_buffer_mipmaps(RID p_render_target,
return; //nothing to do
}
}
glDisable(GL_BLEND);
GLES3::CopyEffects::get_singleton()->gaussian_blur(rt->backbuffer, rt->mipmap_count, region, rt->size);
glEnable(GL_BLEND); // 2D starts with blend enabled.

GLES3::CopyEffects::get_singleton()->bilinear_blur(rt->backbuffer, rt->mipmap_count, region);
glBindFramebuffer(GL_FRAMEBUFFER, rt->backbuffer_fbo);
}

Expand Down