Brad Bishop | 6ef3265 | 2018-10-09 18:59:25 +0100 | [diff] [blame] | 1 | From c215ba1d52a3d4ef03af3ab1a5baa1863f812aed Mon Sep 17 00:00:00 2001 |
| 2 | From: =?UTF-8?q?Andreas=20M=C3=BCller?= <schnitzeltony@gmail.com> |
| 3 | Date: Fri, 24 Aug 2018 23:10:25 +0200 |
| 4 | Subject: [PATCH] GLES2: Get sin/cos out of vertex shader |
| 5 | MIME-Version: 1.0 |
| 6 | Content-Type: text/plain; charset=UTF-8 |
| 7 | Content-Transfer-Encoding: 8bit |
| 8 | |
| 9 | The only place angle is activated and causes effect is RenderCopyEx. All other |
| 10 | methods which use vertex shader, leave angle disabled and cause useless sin/cos |
| 11 | calculation in shader. |
| 12 | |
| 13 | To get around shader's interface is changed to a vector that contains results |
| 14 | of sin and cos. To behave properly when disabled, cos value is set with offset |
| 15 | -1.0 making 0.0 default when deactivated. |
| 16 | |
| 17 | As nice side effect it simplifies GLES2_UpdateVertexBuffer: All attributes are |
| 18 | vectors now. |
| 19 | |
| 20 | Additional background: |
| 21 | |
| 22 | * On RaspberryPi it gives a performace win for operations. Tested with |
| 23 | [1] numbers go down for 5-10% (not easy to estimate due to huge variation). |
| 24 | * SDL_RenderCopyEx was tested with [2] |
| 25 | * It works around left rotated display caused by low accuracy sin implemetation |
| 26 | in RaspberryPi/VC4 [3] |
| 27 | |
| 28 | Upstream-Status: Accepted [4] |
| 29 | |
| 30 | [1] https://github.com/schnitzeltony/sdl2box |
| 31 | [2] https://github.com/schnitzeltony/sdl2rendercopyex |
| 32 | [3] https://github.com/anholt/mesa/issues/110 |
| 33 | [4] https://hg.libsdl.org/SDL/rev/e5a666405750 |
| 34 | |
| 35 | Signed-off-by: Andreas Müller <schnitzeltony@gmail.com> |
| 36 | --- |
| 37 | src/render/opengles2/SDL_render_gles2.c | 17 ++++++++++++----- |
| 38 | src/render/opengles2/SDL_shaders_gles2.c | 14 +++++++++----- |
| 39 | 2 files changed, 21 insertions(+), 10 deletions(-) |
| 40 | |
| 41 | diff --git a/src/render/opengles2/SDL_render_gles2.c b/src/render/opengles2/SDL_render_gles2.c |
| 42 | index 14671f7c8..7c54a7333 100644 |
| 43 | --- a/src/render/opengles2/SDL_render_gles2.c |
| 44 | +++ b/src/render/opengles2/SDL_render_gles2.c |
| 45 | @@ -1530,7 +1530,7 @@ GLES2_UpdateVertexBuffer(SDL_Renderer *renderer, GLES2_Attribute attr, |
| 46 | GLES2_DriverContext *data = (GLES2_DriverContext *)renderer->driverdata; |
| 47 | |
| 48 | #if !SDL_GLES2_USE_VBOS |
| 49 | - data->glVertexAttribPointer(attr, attr == GLES2_ATTRIBUTE_ANGLE ? 1 : 2, GL_FLOAT, GL_FALSE, 0, vertexData); |
| 50 | + data->glVertexAttribPointer(attr, 2, GL_FLOAT, GL_FALSE, 0, vertexData); |
| 51 | #else |
| 52 | if (!data->vertex_buffers[attr]) { |
| 53 | data->glGenBuffers(1, &data->vertex_buffers[attr]); |
| 54 | @@ -1545,7 +1545,7 @@ GLES2_UpdateVertexBuffer(SDL_Renderer *renderer, GLES2_Attribute attr, |
| 55 | data->glBufferSubData(GL_ARRAY_BUFFER, 0, dataSizeInBytes, vertexData); |
| 56 | } |
| 57 | |
| 58 | - data->glVertexAttribPointer(attr, attr == GLES2_ATTRIBUTE_ANGLE ? 1 : 2, GL_FLOAT, GL_FALSE, 0, 0); |
| 59 | + data->glVertexAttribPointer(attr, 2, GL_FLOAT, GL_FALSE, 0, 0); |
| 60 | #endif |
| 61 | |
| 62 | return 0; |
| 63 | @@ -1853,6 +1853,8 @@ GLES2_RenderCopy(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect *s |
| 64 | return GL_CheckError("", renderer); |
| 65 | } |
| 66 | |
| 67 | +#define PI 3.14159265f |
| 68 | + |
| 69 | static int |
| 70 | GLES2_RenderCopyEx(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect *srcrect, |
| 71 | const SDL_FRect *dstrect, const double angle, const SDL_FPoint *center, const SDL_RendererFlip flip) |
| 72 | @@ -1861,8 +1863,9 @@ GLES2_RenderCopyEx(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect |
| 73 | GLfloat vertices[8]; |
| 74 | GLfloat texCoords[8]; |
| 75 | GLfloat translate[8]; |
| 76 | - GLfloat fAngle[4]; |
| 77 | + GLfloat fAngle[8]; |
| 78 | GLfloat tmp; |
| 79 | + float radian_angle; |
| 80 | |
| 81 | GLES2_ActivateRenderer(renderer); |
| 82 | |
| 83 | @@ -1872,7 +1875,11 @@ GLES2_RenderCopyEx(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect |
| 84 | |
| 85 | data->glEnableVertexAttribArray(GLES2_ATTRIBUTE_CENTER); |
| 86 | data->glEnableVertexAttribArray(GLES2_ATTRIBUTE_ANGLE); |
| 87 | - fAngle[0] = fAngle[1] = fAngle[2] = fAngle[3] = (GLfloat)(360.0f - angle); |
| 88 | + |
| 89 | + radian_angle = PI * (360.0f - angle) / 180.f; |
| 90 | + fAngle[0] = fAngle[2] = fAngle[4] = fAngle[6] = (GLfloat)sin(radian_angle); |
| 91 | + /* render expects cos value - 1 (see GLES2_VertexSrc_Default_) */ |
| 92 | + fAngle[1] = fAngle[3] = fAngle[5] = fAngle[7] = (GLfloat)cos(radian_angle) - 1.0f; |
| 93 | /* Calculate the center of rotation */ |
| 94 | translate[0] = translate[2] = translate[4] = translate[6] = (center->x + dstrect->x); |
| 95 | translate[1] = translate[3] = translate[5] = translate[7] = (center->y + dstrect->y); |
| 96 | @@ -1901,7 +1908,7 @@ GLES2_RenderCopyEx(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect |
| 97 | data->glVertexAttribPointer(GLES2_ATTRIBUTE_CENTER, 2, GL_FLOAT, GL_FALSE, 0, translate); |
| 98 | data->glVertexAttribPointer(GLES2_ATTRIBUTE_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices);*/ |
| 99 | |
| 100 | - GLES2_UpdateVertexBuffer(renderer, GLES2_ATTRIBUTE_ANGLE, fAngle, 4 * sizeof(GLfloat)); |
| 101 | + GLES2_UpdateVertexBuffer(renderer, GLES2_ATTRIBUTE_ANGLE, fAngle, 8 * sizeof(GLfloat)); |
| 102 | GLES2_UpdateVertexBuffer(renderer, GLES2_ATTRIBUTE_CENTER, translate, 8 * sizeof(GLfloat)); |
| 103 | GLES2_UpdateVertexBuffer(renderer, GLES2_ATTRIBUTE_POSITION, vertices, 8 * sizeof(GLfloat)); |
| 104 | |
| 105 | diff --git a/src/render/opengles2/SDL_shaders_gles2.c b/src/render/opengles2/SDL_shaders_gles2.c |
| 106 | index b0bcdff25..f428a4945 100644 |
| 107 | --- a/src/render/opengles2/SDL_shaders_gles2.c |
| 108 | +++ b/src/render/opengles2/SDL_shaders_gles2.c |
| 109 | @@ -30,20 +30,24 @@ |
| 110 | /************************************************************************************************* |
| 111 | * Vertex/fragment shader source * |
| 112 | *************************************************************************************************/ |
| 113 | - |
| 114 | +/* Notes on a_angle: |
| 115 | + * It is a vector containing sin and cos for rotation matrix |
| 116 | + * To get correct rotation for most cases when a_angle is disabled cos |
| 117 | + value is decremented by 1.0 to get proper output with 0.0 which is |
| 118 | + default value |
| 119 | +*/ |
| 120 | static const Uint8 GLES2_VertexSrc_Default_[] = " \ |
| 121 | uniform mat4 u_projection; \ |
| 122 | attribute vec2 a_position; \ |
| 123 | attribute vec2 a_texCoord; \ |
| 124 | - attribute float a_angle; \ |
| 125 | + attribute vec2 a_angle; \ |
| 126 | attribute vec2 a_center; \ |
| 127 | varying vec2 v_texCoord; \ |
| 128 | \ |
| 129 | void main() \ |
| 130 | { \ |
| 131 | - float angle = radians(a_angle); \ |
| 132 | - float c = cos(angle); \ |
| 133 | - float s = sin(angle); \ |
| 134 | + float s = a_angle[0]; \ |
| 135 | + float c = a_angle[1] + 1.0; \ |
| 136 | mat2 rotationMatrix = mat2(c, -s, s, c); \ |
| 137 | vec2 position = rotationMatrix * (a_position - a_center) + a_center; \ |
| 138 | v_texCoord = a_texCoord; \ |
| 139 | -- |
| 140 | 2.14.4 |
| 141 | |