From 87bc1fb55240839f00e4346e56576ea9f7a20d67 Mon Sep 17 00:00:00 2001 From: Andreas M?ller Date: Tue, 28 Aug 2018 12:57:51 -0700 Subject: [PATCH] GLES2: Get sin/cos out of vertex shader 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] [1] https://github.com/schnitzeltony/sdl2box [2] https://github.com/schnitzeltony/sdl2rendercopyex [3] https://github.com/anholt/mesa/issues/110 Signed-off-by: Andreas M?ller --- 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 a2399a7ac4d94..af83740ec9ba2 100644 --- a/src/render/opengles2/SDL_render_gles2.c +++ b/src/render/opengles2/SDL_render_gles2.c @@ -1534,7 +1534,7 @@ 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]); @@ -1549,7 +1549,7 @@ 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; @@ -1857,6 +1857,8 @@ 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) @@ -1865,8 +1867,9 @@ 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); @@ -1876,7 +1879,11 @@ 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); @@ -1905,7 +1912,7 @@ 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 b0bcdff25e1fe..f428a494567b4 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; \