1 files changed, 278 insertions, 0 deletions
diff --git a/src/opengl/swapchain.c b/src/opengl/swapchain.c
new file mode 100644
index 0000000..46d5f9e
--- /dev/null
+++ b/src/opengl/swapchain.c
@@ -0,0 +1,278 @@
+/*
+ * This file is part of libplacebo.
+ *
+ * libplacebo is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * libplacebo is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with libplacebo.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "common.h"
+#include "formats.h"
+#include "gpu.h"
+#include "swapchain.h"
+#include "utils.h"
+#include "pl_thread.h"
+
+struct priv {
+    struct pl_sw_fns impl;
+
+    struct pl_opengl_swapchain_params params;
+    pl_opengl gl;
+    pl_mutex lock;
+    bool has_sync;
+
+    // current parameters
+    pl_tex fb;
+    bool frame_started;
+
+    // vsync fences
+    int swapchain_depth;
+    PL_ARRAY(GLsync) vsync_fences;
+};
+
+static const struct pl_sw_fns opengl_swapchain;
+
+pl_swapchain pl_opengl_create_swapchain(pl_opengl pl_gl,
+                              const struct pl_opengl_swapchain_params *params)
+{
+    pl_gpu gpu = pl_gl->gpu;
+
+    if (params->max_swapchain_depth < 0) {
+        PL_ERR(gpu, "Tried specifying negative swapchain depth?");
+        return NULL;
+    }
+
+    if (!gl_make_current(pl_gl))
+        return NULL;
+
+    struct pl_swapchain_t *sw = pl_zalloc_obj(NULL, sw, struct priv);
+    sw->log = gpu->log;
+    sw->gpu = gpu;
+
+    struct priv *p = PL_PRIV(sw);
+    pl_mutex_init(&p->lock);
+    p->impl = opengl_swapchain;
+    p->params = *params;
+    p->has_sync = pl_opengl_has_ext(pl_gl, "GL_ARB_sync");
+    p->gl = pl_gl;
+
+    gl_release_current(pl_gl);
+    return sw;
+}
+
+static void gl_sw_destroy(pl_swapchain sw)
+{
+    pl_gpu gpu = sw->gpu;
+    struct priv *p = PL_PRIV(sw);
+
+    pl_gpu_flush(gpu);
+    pl_tex_destroy(gpu, &p->fb);
+    pl_mutex_destroy(&p->lock);
+    pl_free((void *) sw);
+}
+
+static int gl_sw_latency(pl_swapchain sw)
+{
+    struct priv *p = PL_PRIV(sw);
+    return p->params.max_swapchain_depth;
+}
+
+static bool gl_sw_resize(pl_swapchain sw, int *width, int *height)
+{
+    struct priv *p = PL_PRIV(sw);
+    const int w = *width, h = *height;
+
+    pl_mutex_lock(&p->lock);
+    if (p->fb && w == p->fb->params.w && h == p->fb->params.h) {
+        pl_mutex_unlock(&p->lock);
+        return true;
+    }
+
+    if (p->frame_started && (w || h)) {
+        PL_ERR(sw, "Tried resizing the swapchain while a frame was in progress! "
+               "Please submit the current frame first.");
+        pl_mutex_unlock(&p->lock);
+        return false;
+    }
+
+    if (w && h) {
+        pl_tex_destroy(sw->gpu, &p->fb);
+        p->fb = pl_opengl_wrap(sw->gpu, pl_opengl_wrap_params(
+            .framebuffer = p->params.framebuffer.id,
+            .width = w,
+            .height = h,
+        ));
+        if (!p->fb) {
+            PL_ERR(sw, "Failed wrapping OpenGL framebuffer!");
+            pl_mutex_unlock(&p->lock);
+            return false;
+        }
+    }
+
+    if (!p->fb) {
+        PL_ERR(sw, "Tried calling `pl_swapchain_resize` with unknown size! "
+               "This is forbidden for OpenGL. The first call to "
+               "`pl_swapchain_resize` must include the width and height of the "
+               "swapchain, because there's no way to figure this out from "
+               "within the API.");
+        pl_mutex_unlock(&p->lock);
+        return false;
+    }
+
+    *width = p->fb->params.w;
+    *height = p->fb->params.h;
+    pl_mutex_unlock(&p->lock);
+    return true;
+}
+
+void pl_opengl_swapchain_update_fb(pl_swapchain sw,
+                                   const struct pl_opengl_framebuffer *fb)
+{
+    struct priv *p = PL_PRIV(sw);
+    pl_mutex_lock(&p->lock);
+    if (p->frame_started) {
+        PL_ERR(sw,"Tried calling `pl_opengl_swapchain_update_fb` while a frame "
+               "was in progress! Please submit the current frame first.");
+        pl_mutex_unlock(&p->lock);
+        return;
+    }
+
+    if (p->params.framebuffer.id != fb->id)
+        pl_tex_destroy(sw->gpu, &p->fb);
+
+    p->params.framebuffer = *fb;
+    pl_mutex_unlock(&p->lock);
+}
+
+static bool gl_sw_start_frame(pl_swapchain sw,
+                              struct pl_swapchain_frame *out_frame)
+{
+    struct priv *p = PL_PRIV(sw);
+    pl_mutex_lock(&p->lock);
+    bool ok = false;
+
+    if (!p->fb) {
+        PL_ERR(sw, "Unknown framebuffer size. Please call `pl_swapchain_resize` "
+               "before `pl_swapchain_start_frame` for OpenGL swapchains!");
+        goto error;
+    }
+
+    if (p->frame_started) {
+        PL_ERR(sw, "Attempted calling `pl_swapchain_start` while a frame was "
+               "already in progress! Call `pl_swapchain_submit_frame` first.");
+        goto error;
+    }
+
+    if (!gl_make_current(p->gl))
+        goto error;
+
+    *out_frame = (struct pl_swapchain_frame) {
+        .fbo = p->fb,
+        .flipped = !p->params.framebuffer.flipped,
+        .color_repr = {
+            .sys = PL_COLOR_SYSTEM_RGB,
+            .levels = PL_COLOR_LEVELS_FULL,
+            .alpha = p->fb->params.format->num_components == 4
+                        ? PL_ALPHA_PREMULTIPLIED
+                        : PL_ALPHA_UNKNOWN,
+            .bits = {
+                // Just use the red channel in the absence of anything more
+                // sane to do, because the red channel is both guaranteed to
+                // exist and also typically has the minimum number of bits
+                // (which is arguably what matters for dithering)
+                .sample_depth = p->fb->params.format->component_depth[0],
+                .color_depth = p->fb->params.format->component_depth[0],
+            },
+        },
+        .color_space = pl_color_space_monitor,
+    };
+
+    p->frame_started = gl_check_err(sw->gpu, "gl_sw_start_frame");
+    if (!p->frame_started)
+        goto error;
+
+    // keep p->lock held
+    gl_release_current(p->gl);
+    return true;
+
+error:
+    gl_release_current(p->gl);
+    pl_mutex_unlock(&p->lock);
+    return ok;
+}
+
+static bool gl_sw_submit_frame(pl_swapchain sw)
+{
+    struct priv *p = PL_PRIV(sw);
+    struct gl_ctx *glctx = PL_PRIV(p->gl);
+    const gl_funcs *gl = &glctx->func;
+    if (!gl_make_current(p->gl)) {
+        p->frame_started = false;
+        pl_mutex_unlock(&p->lock);
+        return false;
+    }
+
+    pl_assert(p->frame_started);
+    if (p->has_sync && p->params.max_swapchain_depth) {
+        GLsync fence = gl->FenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
+        if (fence)
+            PL_ARRAY_APPEND(sw, p->vsync_fences, fence);
+    }
+
+    gl->Flush();
+    p->frame_started = false;
+    bool ok = gl_check_err(sw->gpu, "gl_sw_submit_frame");
+    gl_release_current(p->gl);
+    pl_mutex_unlock(&p->lock);
+
+    return ok;
+}
+
+static void gl_sw_swap_buffers(pl_swapchain sw)
+{
+    struct priv *p = PL_PRIV(sw);
+    struct gl_ctx *glctx = PL_PRIV(p->gl);
+    const gl_funcs *gl = &glctx->func;
+    if (!p->params.swap_buffers) {
+        PL_ERR(sw, "`pl_swapchain_swap_buffers` called but no "
+               "`params.swap_buffers` callback set!");
+        return;
+    }
+
+    pl_mutex_lock(&p->lock);
+    if (!gl_make_current(p->gl)) {
+        pl_mutex_unlock(&p->lock);
+        return;
+    }
+
+    p->params.swap_buffers(p->params.priv);
+
+    const int max_depth = p->params.max_swapchain_depth;
+    while (max_depth && p->vsync_fences.num >= max_depth) {
+        gl->ClientWaitSync(p->vsync_fences.elem[0], GL_SYNC_FLUSH_COMMANDS_BIT, 1e9);
+        gl->DeleteSync(p->vsync_fences.elem[0]);
+        PL_ARRAY_REMOVE_AT(p->vsync_fences, 0);
+    }
+
+    gl_check_err(sw->gpu, "gl_sw_swap_buffers");
+    gl_release_current(p->gl);
+    pl_mutex_unlock(&p->lock);
+}
+
+static const struct pl_sw_fns opengl_swapchain = {
+    .destroy      = gl_sw_destroy,
+    .latency      = gl_sw_latency,
+    .resize       = gl_sw_resize,
+    .start_frame  = gl_sw_start_frame,
+    .submit_frame = gl_sw_submit_frame,
+    .swap_buffers = gl_sw_swap_buffers,
+};