obs-studio/plugins/obs-transitions/transition-fade.c
jpark37 9d7330ca44 obs-transitions: Blend in linear space
Color mismatch is apparent when using source transitions, which lerps
against transparent black and blends into the canvas nonlinearly. When
the transition is done, the blend switches to linear, leading to a pop.

Fix the issue by blending into the canvas in linear space. The lerp is
still nonlinear by design.
2021-05-08 20:53:44 -07:00

107 lines
2.5 KiB
C

#include <obs-module.h>
struct fade_info {
obs_source_t *source;
gs_effect_t *effect;
gs_eparam_t *a_param;
gs_eparam_t *b_param;
gs_eparam_t *fade_param;
};
static const char *fade_get_name(void *type_data)
{
UNUSED_PARAMETER(type_data);
return obs_module_text("FadeTransition");
}
static void *fade_create(obs_data_t *settings, obs_source_t *source)
{
struct fade_info *fade;
char *file = obs_module_file("fade_transition.effect");
gs_effect_t *effect;
obs_enter_graphics();
effect = gs_effect_create_from_file(file, NULL);
obs_leave_graphics();
bfree(file);
if (!effect) {
blog(LOG_ERROR, "Could not find fade_transition.effect");
return NULL;
}
fade = bmalloc(sizeof(*fade));
fade->source = source;
fade->effect = effect;
fade->a_param = gs_effect_get_param_by_name(effect, "tex_a");
fade->b_param = gs_effect_get_param_by_name(effect, "tex_b");
fade->fade_param = gs_effect_get_param_by_name(effect, "fade_val");
UNUSED_PARAMETER(settings);
return fade;
}
static void fade_destroy(void *data)
{
struct fade_info *fade = data;
bfree(fade);
}
static void fade_callback(void *data, gs_texture_t *a, gs_texture_t *b, float t,
uint32_t cx, uint32_t cy)
{
struct fade_info *fade = data;
const bool previous = gs_framebuffer_srgb_enabled();
gs_enable_framebuffer_srgb(true);
gs_effect_set_texture(fade->a_param, a);
gs_effect_set_texture(fade->b_param, b);
gs_effect_set_float(fade->fade_param, t);
while (gs_effect_loop(fade->effect, "Fade"))
gs_draw_sprite(NULL, 0, cx, cy);
gs_enable_framebuffer_srgb(previous);
}
static void fade_video_render(void *data, gs_effect_t *effect)
{
struct fade_info *fade = data;
obs_transition_video_render(fade->source, fade_callback);
UNUSED_PARAMETER(effect);
}
static float mix_a(void *data, float t)
{
UNUSED_PARAMETER(data);
return 1.0f - t;
}
static float mix_b(void *data, float t)
{
UNUSED_PARAMETER(data);
return t;
}
static bool fade_audio_render(void *data, uint64_t *ts_out,
struct obs_source_audio_mix *audio,
uint32_t mixers, size_t channels,
size_t sample_rate)
{
struct fade_info *fade = data;
return obs_transition_audio_render(fade->source, ts_out, audio, mixers,
channels, sample_rate, mix_a, mix_b);
}
struct obs_source_info fade_transition = {
.id = "fade_transition",
.type = OBS_SOURCE_TYPE_TRANSITION,
.get_name = fade_get_name,
.create = fade_create,
.destroy = fade_destroy,
.video_render = fade_video_render,
.audio_render = fade_audio_render,
};