[OE-core] [sumo][PATCH] libsdl2: Fix left rotated display for RaspPi/VC4/GLES2
Andreas Müller
schnitzeltony at gmail.com
Thu Sep 27 19:06:48 UTC 2018
The patch should increase performance for libsdl2 on GLES2 too.
(From OE-Core rev: 52f9659f2bb44affec2f67935df01f13b6ff3e02)
Signed-off-by: Andreas Müller <schnitzeltony at gmail.com>
Signed-off-by: Richard Purdie <richard.purdie at linuxfoundation.org>
---
...01-GLES2-Get-sin-cos-out-of-vertex-shader.patch | 141 +++++++++++++++++++++
meta/recipes-graphics/libsdl2/libsdl2_2.0.8.bb | 1 +
2 files changed, 142 insertions(+)
create mode 100644 meta/recipes-graphics/libsdl2/libsdl2/0001-GLES2-Get-sin-cos-out-of-vertex-shader.patch
diff --git a/meta/recipes-graphics/libsdl2/libsdl2/0001-GLES2-Get-sin-cos-out-of-vertex-shader.patch b/meta/recipes-graphics/libsdl2/libsdl2/0001-GLES2-Get-sin-cos-out-of-vertex-shader.patch
new file mode 100644
index 0000000000..9b32b3788d
--- /dev/null
+++ b/meta/recipes-graphics/libsdl2/libsdl2/0001-GLES2-Get-sin-cos-out-of-vertex-shader.patch
@@ -0,0 +1,141 @@
+From c215ba1d52a3d4ef03af3ab1a5baa1863f812aed Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Andreas=20M=C3=BCller?= <schnitzeltony at gmail.com>
+Date: Fri, 24 Aug 2018 23:10:25 +0200
+Subject: [PATCH] GLES2: Get sin/cos out of vertex shader
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+The only place angle is activated and causes effect is RenderCopyEx. All other
+methods which use vertex shader, leave angle disabled and cause useless sin/cos
+calculation in shader.
+
+To get around shader's interface is changed to a vector that contains results
+of sin and cos. To behave properly when disabled, cos value is set with offset
+-1.0 making 0.0 default when deactivated.
+
+As nice side effect it simplifies GLES2_UpdateVertexBuffer: All attributes are
+vectors now.
+
+Additional background:
+
+* On RaspberryPi it gives a performace win for operations. Tested with
+ [1] numbers go down for 5-10% (not easy to estimate due to huge variation).
+* SDL_RenderCopyEx was tested with [2]
+* It works around left rotated display caused by low accuracy sin implemetation
+ in RaspberryPi/VC4 [3]
+
+Upstream-Status: Accepted [4]
+
+[1] https://github.com/schnitzeltony/sdl2box
+[2] https://github.com/schnitzeltony/sdl2rendercopyex
+[3] https://github.com/anholt/mesa/issues/110
+[4] https://hg.libsdl.org/SDL/rev/e5a666405750
+
+Signed-off-by: Andreas Müller <schnitzeltony at gmail.com>
+---
+ src/render/opengles2/SDL_render_gles2.c | 17 ++++++++++++-----
+ src/render/opengles2/SDL_shaders_gles2.c | 14 +++++++++-----
+ 2 files changed, 21 insertions(+), 10 deletions(-)
+
+diff --git a/src/render/opengles2/SDL_render_gles2.c b/src/render/opengles2/SDL_render_gles2.c
+index 14671f7c8..7c54a7333 100644
+--- a/src/render/opengles2/SDL_render_gles2.c
++++ b/src/render/opengles2/SDL_render_gles2.c
+@@ -1530,7 +1530,7 @@ GLES2_UpdateVertexBuffer(SDL_Renderer *renderer, GLES2_Attribute attr,
+ GLES2_DriverContext *data = (GLES2_DriverContext *)renderer->driverdata;
+
+ #if !SDL_GLES2_USE_VBOS
+- data->glVertexAttribPointer(attr, attr == GLES2_ATTRIBUTE_ANGLE ? 1 : 2, GL_FLOAT, GL_FALSE, 0, vertexData);
++ data->glVertexAttribPointer(attr, 2, GL_FLOAT, GL_FALSE, 0, vertexData);
+ #else
+ if (!data->vertex_buffers[attr]) {
+ data->glGenBuffers(1, &data->vertex_buffers[attr]);
+@@ -1545,7 +1545,7 @@ GLES2_UpdateVertexBuffer(SDL_Renderer *renderer, GLES2_Attribute attr,
+ data->glBufferSubData(GL_ARRAY_BUFFER, 0, dataSizeInBytes, vertexData);
+ }
+
+- data->glVertexAttribPointer(attr, attr == GLES2_ATTRIBUTE_ANGLE ? 1 : 2, GL_FLOAT, GL_FALSE, 0, 0);
++ data->glVertexAttribPointer(attr, 2, GL_FLOAT, GL_FALSE, 0, 0);
+ #endif
+
+ return 0;
+@@ -1853,6 +1853,8 @@ GLES2_RenderCopy(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect *s
+ return GL_CheckError("", renderer);
+ }
+
++#define PI 3.14159265f
++
+ static int
+ GLES2_RenderCopyEx(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect *srcrect,
+ const SDL_FRect *dstrect, const double angle, const SDL_FPoint *center, const SDL_RendererFlip flip)
+@@ -1861,8 +1863,9 @@ GLES2_RenderCopyEx(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect
+ GLfloat vertices[8];
+ GLfloat texCoords[8];
+ GLfloat translate[8];
+- GLfloat fAngle[4];
++ GLfloat fAngle[8];
+ GLfloat tmp;
++ float radian_angle;
+
+ GLES2_ActivateRenderer(renderer);
+
+@@ -1872,7 +1875,11 @@ GLES2_RenderCopyEx(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect
+
+ data->glEnableVertexAttribArray(GLES2_ATTRIBUTE_CENTER);
+ data->glEnableVertexAttribArray(GLES2_ATTRIBUTE_ANGLE);
+- fAngle[0] = fAngle[1] = fAngle[2] = fAngle[3] = (GLfloat)(360.0f - angle);
++
++ radian_angle = PI * (360.0f - angle) / 180.f;
++ fAngle[0] = fAngle[2] = fAngle[4] = fAngle[6] = (GLfloat)sin(radian_angle);
++ /* render expects cos value - 1 (see GLES2_VertexSrc_Default_) */
++ fAngle[1] = fAngle[3] = fAngle[5] = fAngle[7] = (GLfloat)cos(radian_angle) - 1.0f;
+ /* Calculate the center of rotation */
+ translate[0] = translate[2] = translate[4] = translate[6] = (center->x + dstrect->x);
+ translate[1] = translate[3] = translate[5] = translate[7] = (center->y + dstrect->y);
+@@ -1901,7 +1908,7 @@ GLES2_RenderCopyEx(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect
+ data->glVertexAttribPointer(GLES2_ATTRIBUTE_CENTER, 2, GL_FLOAT, GL_FALSE, 0, translate);
+ data->glVertexAttribPointer(GLES2_ATTRIBUTE_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices);*/
+
+- GLES2_UpdateVertexBuffer(renderer, GLES2_ATTRIBUTE_ANGLE, fAngle, 4 * sizeof(GLfloat));
++ GLES2_UpdateVertexBuffer(renderer, GLES2_ATTRIBUTE_ANGLE, fAngle, 8 * sizeof(GLfloat));
+ GLES2_UpdateVertexBuffer(renderer, GLES2_ATTRIBUTE_CENTER, translate, 8 * sizeof(GLfloat));
+ GLES2_UpdateVertexBuffer(renderer, GLES2_ATTRIBUTE_POSITION, vertices, 8 * sizeof(GLfloat));
+
+diff --git a/src/render/opengles2/SDL_shaders_gles2.c b/src/render/opengles2/SDL_shaders_gles2.c
+index b0bcdff25..f428a4945 100644
+--- a/src/render/opengles2/SDL_shaders_gles2.c
++++ b/src/render/opengles2/SDL_shaders_gles2.c
+@@ -30,20 +30,24 @@
+ /*************************************************************************************************
+ * Vertex/fragment shader source *
+ *************************************************************************************************/
+-
++/* Notes on a_angle:
++ * It is a vector containing sin and cos for rotation matrix
++ * To get correct rotation for most cases when a_angle is disabled cos
++ value is decremented by 1.0 to get proper output with 0.0 which is
++ default value
++*/
+ static const Uint8 GLES2_VertexSrc_Default_[] = " \
+ uniform mat4 u_projection; \
+ attribute vec2 a_position; \
+ attribute vec2 a_texCoord; \
+- attribute float a_angle; \
++ attribute vec2 a_angle; \
+ attribute vec2 a_center; \
+ varying vec2 v_texCoord; \
+ \
+ void main() \
+ { \
+- float angle = radians(a_angle); \
+- float c = cos(angle); \
+- float s = sin(angle); \
++ float s = a_angle[0]; \
++ float c = a_angle[1] + 1.0; \
+ mat2 rotationMatrix = mat2(c, -s, s, c); \
+ vec2 position = rotationMatrix * (a_position - a_center) + a_center; \
+ v_texCoord = a_texCoord; \
+--
+2.14.4
+
diff --git a/meta/recipes-graphics/libsdl2/libsdl2_2.0.8.bb b/meta/recipes-graphics/libsdl2/libsdl2_2.0.8.bb
index c0cf70d7fd..8092fad11e 100644
--- a/meta/recipes-graphics/libsdl2/libsdl2_2.0.8.bb
+++ b/meta/recipes-graphics/libsdl2/libsdl2_2.0.8.bb
@@ -16,6 +16,7 @@ DEPENDS_class-nativesdk = "${@bb.utils.contains('DISTRO_FEATURES', 'x11', 'virtu
SRC_URI = " \
http://www.libsdl.org/release/SDL2-${PV}.tar.gz \
+ file://0001-GLES2-Get-sin-cos-out-of-vertex-shader.patch \
"
S = "${WORKDIR}/SDL2-${PV}"
--
2.14.4
More information about the Openembedded-core
mailing list