From f33853f8619f0e775745a46c28434af8841a48f6 Mon Sep 17 00:00:00 2001 From: Jose Maria Casanova Crespo Date: Fri, 6 Mar 2026 12:07:30 +0100 Subject: [PATCH] render/gles2: add scissor-based clipping for tile-based renderers Add an optional scissor-based clipping strategy to the GLES2 render pass, it is enabled with WLR_GLES2_SCISSOR_CLIP=1 env var. And it is disabled by default so it doesn't affect current users. On tile-based renderers like V3D (Broadcom VideoCore, used in Raspberry Pi), not using scissoring makes the GPU to render the full-surface. If scissor is applied only the tiles affected are load/render/stored reducing the GPU usage. Patch backported to wlroots 0.19 with labwc on Raspberry Pi OS with v3d running glxgear 300x300 on top left corner of screen: - Before: labwc uses 21.5% of GPU render availability. - After : labwc uses 3.3% of GPU render availability. This patch over wlroots master with sway on Raspberry Pi OS with v3d running glxgear half-screen and a terminal half screen: - Before: sway uses 23.5% of GPU render availability. - After : sway uses 13.6% of GPU render availability. --- include/render/gles2.h | 2 ++ render/gles2/pass.c | 78 +++++++++++++++++++++++++++-------------- render/gles2/renderer.c | 6 ++++ 3 files changed, 59 insertions(+), 27 deletions(-) diff --git a/include/render/gles2.h b/include/render/gles2.h index 6b852dcb7..633b89df1 100644 --- a/include/render/gles2.h +++ b/include/render/gles2.h @@ -87,6 +87,8 @@ struct wlr_gles2_renderer { struct wl_list buffers; // wlr_gles2_buffer.link struct wl_list textures; // wlr_gles2_texture.link + + bool scissor; // enables scissor clipping for tile render GPUs }; struct wlr_gles2_render_timer { diff --git a/render/gles2/pass.c b/render/gles2/pass.c index a70ea1320..9c39ac193 100644 --- a/render/gles2/pass.c +++ b/render/gles2/pass.c @@ -75,7 +75,7 @@ out: return ok; } -static void render(const struct wlr_box *box, const pixman_region32_t *clip, GLint attrib) { +static void render(const struct wlr_box *box, const pixman_region32_t *clip, GLint attrib, bool scissor) { pixman_region32_t region; pixman_region32_init_rect(®ion, box->x, box->y, box->width, box->height); @@ -92,31 +92,55 @@ static void render(const struct wlr_box *box, const pixman_region32_t *clip, GLi glEnableVertexAttribArray(attrib); - for (int i = 0; i < rects_len;) { - int batch = rects_len - i < MAX_QUADS ? rects_len - i : MAX_QUADS; - int batch_end = batch + i; - - size_t vert_index = 0; - GLfloat verts[MAX_QUADS * 6 * 2]; - for (; i < batch_end; i++) { - const pixman_box32_t *rect = &rects[i]; - - verts[vert_index++] = (GLfloat)(rect->x1 - box->x) / box->width; - verts[vert_index++] = (GLfloat)(rect->y1 - box->y) / box->height; - verts[vert_index++] = (GLfloat)(rect->x2 - box->x) / box->width; - verts[vert_index++] = (GLfloat)(rect->y1 - box->y) / box->height; - verts[vert_index++] = (GLfloat)(rect->x1 - box->x) / box->width; - verts[vert_index++] = (GLfloat)(rect->y2 - box->y) / box->height; - verts[vert_index++] = (GLfloat)(rect->x2 - box->x) / box->width; - verts[vert_index++] = (GLfloat)(rect->y1 - box->y) / box->height; - verts[vert_index++] = (GLfloat)(rect->x2 - box->x) / box->width; - verts[vert_index++] = (GLfloat)(rect->y2 - box->y) / box->height; - verts[vert_index++] = (GLfloat)(rect->x1 - box->x) / box->width; - verts[vert_index++] = (GLfloat)(rect->y2 - box->y) / box->height; - } - + if (scissor) { + GLfloat verts[12]; glVertexAttribPointer(attrib, 2, GL_FLOAT, GL_FALSE, 0, verts); - glDrawArrays(GL_TRIANGLES, 0, batch * 6); + glEnable(GL_SCISSOR_TEST); + for (int i = 0; i < rects_len; i++) { + const pixman_box32_t *rect = &rects[i]; + verts[0] = (GLfloat)(rect->x1 - box->x) / box->width; + verts[1] = (GLfloat)(rect->y1 - box->y) / box->height; + verts[2] = (GLfloat)(rect->x2 - box->x) / box->width; + verts[3] = (GLfloat)(rect->y1 - box->y) / box->height; + verts[4] = (GLfloat)(rect->x1 - box->x) / box->width; + verts[5] = (GLfloat)(rect->y2 - box->y) / box->height; + verts[6] = (GLfloat)(rect->x2 - box->x) / box->width; + verts[7] = (GLfloat)(rect->y1 - box->y) / box->height; + verts[8] = (GLfloat)(rect->x2 - box->x) / box->width; + verts[9] = (GLfloat)(rect->y2 - box->y) / box->height; + verts[10] = (GLfloat)(rect->x1 - box->x) / box->width; + verts[11] = (GLfloat)(rect->y2 - box->y) / box->height; + glScissor(rect->x1, rect->y1, rect->x2 - rect->x1, rect->y2 - rect->y1); + glDrawArrays(GL_TRIANGLES, 0, 6); + } + glDisable(GL_SCISSOR_TEST); + } else { + for (int i = 0; i < rects_len;) { + int batch = rects_len - i < MAX_QUADS ? rects_len - i : MAX_QUADS; + int batch_end = batch + i; + + size_t vert_index = 0; + GLfloat verts[MAX_QUADS * 6 * 2]; + for (; i < batch_end; i++) { + const pixman_box32_t *rect = &rects[i]; + + verts[vert_index++] = (GLfloat)(rect->x1 - box->x) / box->width; + verts[vert_index++] = (GLfloat)(rect->y1 - box->y) / box->height; + verts[vert_index++] = (GLfloat)(rect->x2 - box->x) / box->width; + verts[vert_index++] = (GLfloat)(rect->y1 - box->y) / box->height; + verts[vert_index++] = (GLfloat)(rect->x1 - box->x) / box->width; + verts[vert_index++] = (GLfloat)(rect->y2 - box->y) / box->height; + verts[vert_index++] = (GLfloat)(rect->x2 - box->x) / box->width; + verts[vert_index++] = (GLfloat)(rect->y1 - box->y) / box->height; + verts[vert_index++] = (GLfloat)(rect->x2 - box->x) / box->width; + verts[vert_index++] = (GLfloat)(rect->y2 - box->y) / box->height; + verts[vert_index++] = (GLfloat)(rect->x1 - box->x) / box->width; + verts[vert_index++] = (GLfloat)(rect->y2 - box->y) / box->height; + } + + glVertexAttribPointer(attrib, 2, GL_FLOAT, GL_FALSE, 0, verts); + glDrawArrays(GL_TRIANGLES, 0, batch * 6); + } } glDisableVertexAttribArray(attrib); @@ -247,7 +271,7 @@ static void render_pass_add_texture(struct wlr_render_pass *wlr_pass, set_proj_matrix(shader->proj, pass->projection_matrix, &dst_box); set_tex_matrix(shader->tex_proj, options->transform, &src_fbox); - render(&dst_box, options->clip, shader->pos_attrib); + render(&dst_box, options->clip, shader->pos_attrib, renderer->scissor); glBindTexture(texture->target, 0); pop_gles2_debug(renderer); @@ -278,7 +302,7 @@ static void render_pass_add_rect(struct wlr_render_pass *wlr_pass, glUseProgram(renderer->shaders.quad.program); set_proj_matrix(renderer->shaders.quad.proj, pass->projection_matrix, &box); glUniform4f(renderer->shaders.quad.color, color->r, color->g, color->b, color->a); - render(&box, options->clip, renderer->shaders.quad.pos_attrib); + render(&box, options->clip, renderer->shaders.quad.pos_attrib, renderer->scissor); } pop_gles2_debug(renderer); diff --git a/render/gles2/renderer.c b/render/gles2/renderer.c index 7f01b8acd..bdae0619b 100644 --- a/render/gles2/renderer.c +++ b/render/gles2/renderer.c @@ -18,6 +18,7 @@ #include "render/egl.h" #include "render/gles2.h" #include "render/pixel_format.h" +#include "util/env.h" #include "util/time.h" #include "common_vert_src.h" @@ -541,6 +542,11 @@ struct wlr_renderer *wlr_gles2_renderer_create(struct wlr_egl *egl) { wlr_log(WLR_INFO, "GL renderer: %s", glGetString(GL_RENDERER)); wlr_log(WLR_INFO, "Supported GLES2 extensions: %s", exts_str); + renderer->scissor = env_parse_bool("WLR_GLES2_SCISSOR_CLIP"); + if (renderer->scissor) { + wlr_log(WLR_INFO, "Enabled scissoring clipping"); + } + if (!renderer->egl->exts.EXT_image_dma_buf_import) { wlr_log(WLR_ERROR, "EGL_EXT_image_dma_buf_import not supported"); free(renderer);