From ff11a2b20717cd5f093646924b3ec085bba9d43b Mon Sep 17 00:00:00 2001 From: Neil Roberts Date: Mon, 19 Nov 2012 17:28:52 +0000 Subject: [PATCH] Use GL_ARB_texture_swizzle to emulate GL_ALPHA textures MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The core profile of GL3 has removed support for component-alpha textures. Previously the GL3 driver would just ignore this and try to create them anyway. This would generate a GL error on Mesa. To fix this the GL texture driver will now create a GL_RED texture when GL_ALPHA textures are not supported natively. It will then set a texture swizzle using the GL_ARB_texture_swizzle extension so that the alpha component will be taken from the red component of the texture. The swizzle is part of the texture object state so it only needs to be set once when the texture is created. The ‘gen’ virtual function of the texture driver has been changed to also take the internal format as a parameter. The GL driver will now set the swizzle as appropriate here. The GL3 driver now reports an error if the texture swizzle extension is not available because Cogl can't really work properly without out it. The extension is part of GL 3.3 so it is quite likely that it has wide support from drivers. Eventually we could get rid of this requirement if we have our own GLSL front-end and we could generate the swizzle ourselves. When uploading or downloading texture data to or from a component-alpha texture, we can no longer rely on GL to do the conversion. The swizzle doesn't have any effect on the texture data functions. In these cases Cogl will now force an intermediate buffer to be used and it will manually do the conversion as it does for the GLES drivers. Reviewed-by: Robert Bragg (cherry picked from commit 32bacf81ebaa3be21a8f26af07d8f6eed6607652) --- cogl/cogl-internal.h | 4 +- cogl/cogl-texture-3d.c | 6 +- cogl/cogl-texture-driver.h | 5 +- cogl/cogl-texture-rectangle.c | 16 ++--- cogl/cogl-texture.c | 38 ++++++++++- cogl/driver/gl/cogl-texture-2d-gl.c | 9 ++- cogl/driver/gl/gl/cogl-driver-gl.c | 39 ++++++++++- cogl/driver/gl/gl/cogl-texture-driver-gl.c | 66 +++++++++++-------- cogl/driver/gl/gles/cogl-driver-gles.c | 3 +- .../driver/gl/gles/cogl-texture-driver-gles.c | 38 +++++------ 10 files changed, 156 insertions(+), 68 deletions(-) diff --git a/cogl/cogl-internal.h b/cogl/cogl-internal.h index c2f387999..7a288aebf 100644 --- a/cogl/cogl-internal.h +++ b/cogl/cogl-internal.h @@ -114,7 +114,9 @@ typedef enum COGL_PRIVATE_FEATURE_BLEND_CONSTANT = 1L<<18, COGL_PRIVATE_FEATURE_QUERY_FRAMEBUFFER_BITS = 1L<<19, COGL_PRIVATE_FEATURE_BUILTIN_POINT_SIZE_UNIFORM = 1L<<20, - COGL_PRIVATE_FEATURE_QUERY_TEXTURE_PARAMETERS = 1L<<21 + COGL_PRIVATE_FEATURE_QUERY_TEXTURE_PARAMETERS = 1L<<21, + COGL_PRIVATE_FEATURE_ALPHA_TEXTURES = 1L<<22, + COGL_PRIVATE_FEATURE_TEXTURE_SWIZZLE = 1L<<23 } CoglPrivateFeatureFlags; /* Sometimes when evaluating pipelines, either during comparisons or diff --git a/cogl/cogl-texture-3d.c b/cogl/cogl-texture-3d.c index 6000b370e..de00cb143 100644 --- a/cogl/cogl-texture-3d.c +++ b/cogl/cogl-texture-3d.c @@ -234,7 +234,8 @@ cogl_texture_3d_new_with_size (CoglContext *ctx, width, height, depth, internal_format); - ctx->texture_driver->gen (ctx, GL_TEXTURE_3D, 1, &tex_3d->gl_texture); + tex_3d->gl_texture = + ctx->texture_driver->gen (ctx, GL_TEXTURE_3D, internal_format); _cogl_bind_gl_texture_transient (GL_TEXTURE_3D, tex_3d->gl_texture, FALSE); @@ -308,7 +309,8 @@ cogl_texture_3d_new_from_bitmap (CoglBitmap *bmp, _cogl_bitmap_unmap (dst_bmp); } - ctx->texture_driver->gen (ctx, GL_TEXTURE_3D, 1, &tex_3d->gl_texture); + tex_3d->gl_texture = + ctx->texture_driver->gen (ctx, GL_TEXTURE_3D, internal_format); ctx->texture_driver->upload_to_gl_3d (ctx, GL_TEXTURE_3D, diff --git a/cogl/cogl-texture-driver.h b/cogl/cogl-texture-driver.h index d4b2b0d86..7a186ba48 100644 --- a/cogl/cogl-texture-driver.h +++ b/cogl/cogl-texture-driver.h @@ -33,11 +33,10 @@ struct _CoglTextureDriver * non-mipmap filters when creating textures. This is to save some memory as * the driver will not allocate room for the mipmap tree. */ - void + GLuint (* gen) (CoglContext *ctx, GLenum gl_target, - GLsizei n, - GLuint *textures); + CoglPixelFormat internal_format); /* * This sets up the glPixelStore state for an upload to a destination with diff --git a/cogl/cogl-texture-rectangle.c b/cogl/cogl-texture-rectangle.c index 3dca1ed4e..1ffeb839d 100644 --- a/cogl/cogl-texture-rectangle.c +++ b/cogl/cogl-texture-rectangle.c @@ -219,10 +219,10 @@ cogl_texture_rectangle_new_with_size (CoglContext *ctx, width, height, internal_format); - ctx->texture_driver->gen (ctx, - GL_TEXTURE_RECTANGLE_ARB, - 1, /* num textures */ - &tex_rect->gl_texture); + tex_rect->gl_texture = + ctx->texture_driver->gen (ctx, + GL_TEXTURE_RECTANGLE_ARB, + internal_format); _cogl_bind_gl_texture_transient (GL_TEXTURE_RECTANGLE_ARB, tex_rect->gl_texture, tex_rect->is_foreign); @@ -274,10 +274,10 @@ cogl_texture_rectangle_new_from_bitmap (CoglBitmap *bmp, cogl_bitmap_get_height (bmp), internal_format); - ctx->texture_driver->gen (ctx, - GL_TEXTURE_RECTANGLE_ARB, - 1, /* num textures */ - &tex_rect->gl_texture); + tex_rect->gl_texture = + ctx->texture_driver->gen (ctx, + GL_TEXTURE_RECTANGLE_ARB, + internal_format); ctx->texture_driver->upload_to_gl (ctx, GL_TEXTURE_RECTANGLE_ARB, tex_rect->gl_texture, diff --git a/cogl/cogl-texture.c b/cogl/cogl-texture.c index 95608c624..e5fe460b9 100644 --- a/cogl/cogl-texture.c +++ b/cogl/cogl-texture.c @@ -206,7 +206,15 @@ _cogl_texture_prepare_for_upload (CoglBitmap *src_bmp, limited number of formats so we must convert using the Cogl bitmap code instead */ - if ((ctx->private_feature_flags & COGL_PRIVATE_FEATURE_FORMAT_CONVERSION)) + /* If the driver doesn't natively support alpha textures then it + * won't work correctly to convert to/from component-alpha + * textures */ + + if ((ctx->private_feature_flags & COGL_PRIVATE_FEATURE_FORMAT_CONVERSION) && + ((ctx->private_feature_flags & COGL_PRIVATE_FEATURE_ALPHA_TEXTURES) || + (src_format != COGL_PIXEL_FORMAT_A_8 && + dst_format != COGL_PIXEL_FORMAT_A_8) || + src_format == dst_format)) { /* If the source format does not have the same premult flag as the dst format then we need to copy and convert it */ @@ -1202,6 +1210,34 @@ cogl_texture_get_data (CoglTexture *texture, closest_format = ((closest_format & ~COGL_PREMULT_BIT) | (texture_format & COGL_PREMULT_BIT)); + /* If the application is requesting a conversion from a + * component-alpha texture and the driver doesn't support them + * natively then we can only read into an alpha-format buffer. In + * this case the driver will be faking the alpha textures with a + * red-component texture and it won't swizzle to the correct format + * while reading */ + if ((ctx->private_feature_flags & COGL_PRIVATE_FEATURE_ALPHA_TEXTURES) == 0) + { + if (texture_format == COGL_PIXEL_FORMAT_A_8) + { + closest_format = COGL_PIXEL_FORMAT_A_8; + closest_gl_format = GL_RED; + closest_gl_type = GL_UNSIGNED_BYTE; + } + else if (format == COGL_PIXEL_FORMAT_A_8) + { + /* If we are converting to a component-alpha texture then we + * need to read all of the components to a temporary buffer + * because there is no way to get just the 4th component. + * Note: it doesn't matter whether the texture is + * pre-multiplied here because we're only going to look at + * the alpha component */ + closest_format = COGL_PIXEL_FORMAT_RGBA_8888; + closest_gl_format = GL_RGBA; + closest_gl_type = GL_UNSIGNED_BYTE; + } + } + /* Is the requested format supported? */ if (closest_format == format) /* Target user data directly */ diff --git a/cogl/driver/gl/cogl-texture-2d-gl.c b/cogl/driver/gl/cogl-texture-2d-gl.c index 1d64d5b2c..7c344acd2 100644 --- a/cogl/driver/gl/cogl-texture-2d-gl.c +++ b/cogl/driver/gl/cogl-texture-2d-gl.c @@ -108,7 +108,8 @@ _cogl_texture_2d_gl_new_with_size (CoglContext *ctx, width, height, internal_format); - ctx->texture_driver->gen (ctx, GL_TEXTURE_2D, 1, &tex_2d->gl_texture); + tex_2d->gl_texture = + ctx->texture_driver->gen (ctx, GL_TEXTURE_2D, internal_format); _cogl_bind_gl_texture_transient (GL_TEXTURE_2D, tex_2d->gl_texture, tex_2d->is_foreign); @@ -164,7 +165,8 @@ _cogl_texture_2d_gl_new_from_bitmap (CoglBitmap *bmp, _cogl_bitmap_unmap (dst_bmp); } - ctx->texture_driver->gen (ctx, GL_TEXTURE_2D, 1, &tex_2d->gl_texture); + tex_2d->gl_texture = + ctx->texture_driver->gen (ctx, GL_TEXTURE_2D, internal_format); ctx->texture_driver->upload_to_gl (ctx, GL_TEXTURE_2D, tex_2d->gl_texture, @@ -198,7 +200,8 @@ _cogl_egl_texture_2d_gl_new_from_image (CoglContext *ctx, width, height, format); - ctx->texture_driver->gen (ctx, GL_TEXTURE_2D, 1, &tex_2d->gl_texture); + tex_2d->gl_texture = + ctx->texture_driver->gen (ctx, GL_TEXTURE_2D, format); _cogl_bind_gl_texture_transient (GL_TEXTURE_2D, tex_2d->gl_texture, FALSE); diff --git a/cogl/driver/gl/gl/cogl-driver-gl.c b/cogl/driver/gl/gl/cogl-driver-gl.c index 2597161fe..6887fb834 100644 --- a/cogl/driver/gl/gl/cogl-driver-gl.c +++ b/cogl/driver/gl/gl/cogl-driver-gl.c @@ -54,6 +54,10 @@ _cogl_driver_pixel_format_from_gl_internal (CoglContext *context, { case GL_ALPHA: case GL_ALPHA4: case GL_ALPHA8: case GL_ALPHA12: case GL_ALPHA16: + /* Cogl only supports one single-component texture so if we have + * ended up with a red texture then it is probably being used as + * a component-alpha texture */ + case GL_RED: *out_format = COGL_PIXEL_FORMAT_A_8; return TRUE; @@ -98,8 +102,20 @@ _cogl_driver_pixel_format_to_gl (CoglContext *context, switch (format) { case COGL_PIXEL_FORMAT_A_8: - glintformat = GL_ALPHA; - glformat = GL_ALPHA; + /* If the driver doesn't natively support alpha textures then we + * will use a red component texture with a swizzle to implement + * the texture */ + if ((context->private_feature_flags & + COGL_PRIVATE_FEATURE_ALPHA_TEXTURES) == 0) + { + glintformat = GL_RED; + glformat = GL_RED; + } + else + { + glintformat = GL_ALPHA; + glformat = GL_ALPHA; + } gltype = GL_UNSIGNED_BYTE; break; case COGL_PIXEL_FORMAT_G_8: @@ -564,11 +580,17 @@ _cogl_driver_update_features (CoglContext *ctx, if (ctx->glGenSamplers) private_flags |= COGL_PRIVATE_FEATURE_SAMPLER_OBJECTS; + if (COGL_CHECK_GL_VERSION (gl_major, gl_minor, 3, 3) || + _cogl_check_extension ("GL_ARB_texture_swizzle", gl_extensions) || + _cogl_check_extension ("GL_EXT_texture_swizzle", gl_extensions)) + private_flags |= COGL_PRIVATE_FEATURE_TEXTURE_SWIZZLE; + if (ctx->driver == COGL_DRIVER_GL) /* Features which are not available in GL 3 */ private_flags |= (COGL_PRIVATE_FEATURE_FIXED_FUNCTION | COGL_PRIVATE_FEATURE_ALPHA_TEST | - COGL_PRIVATE_FEATURE_QUADS); + COGL_PRIVATE_FEATURE_QUADS | + COGL_PRIVATE_FEATURE_ALPHA_TEXTURES); private_flags |= (COGL_PRIVATE_FEATURE_READ_PIXELS_ANY_FORMAT | COGL_PRIVATE_FEATURE_ANY_GL | @@ -583,6 +605,17 @@ _cogl_driver_update_features (CoglContext *ctx, g_strfreev (gl_extensions); + if ((private_flags & (COGL_PRIVATE_FEATURE_ALPHA_TEXTURES | + COGL_PRIVATE_FEATURE_TEXTURE_SWIZZLE)) == 0) + { + _cogl_set_error (error, + COGL_DRIVER_ERROR, + COGL_DRIVER_ERROR_NO_SUITABLE_DRIVER_FOUND, + "The GL_ARB_texture_swizzle extension is required " + "to use the GL3 driver"); + return FALSE; + } + return TRUE; } diff --git a/cogl/driver/gl/gl/cogl-texture-driver-gl.c b/cogl/driver/gl/gl/cogl-texture-driver-gl.c index 2d05c57d5..88f58fa03 100644 --- a/cogl/driver/gl/gl/cogl-texture-driver-gl.c +++ b/cogl/driver/gl/gl/cogl-texture-driver-gl.c @@ -45,41 +45,55 @@ #include #include -static void +#ifndef GL_TEXTURE_SWIZZLE_RGBA +#define GL_TEXTURE_SWIZZLE_RGBA 0x8E46 +#endif + +static GLuint _cogl_texture_driver_gen (CoglContext *ctx, GLenum gl_target, - GLsizei n, - GLuint *textures) + CoglPixelFormat internal_format) { - unsigned int i; + GLuint tex; - GE (ctx, glGenTextures (n, textures)); + GE (ctx, glGenTextures (1, &tex)); - for (i = 0; i < n; i++) + _cogl_bind_gl_texture_transient (gl_target, tex, FALSE); + + switch (gl_target) { - _cogl_bind_gl_texture_transient (gl_target, - textures[i], - FALSE); + case GL_TEXTURE_2D: + case GL_TEXTURE_3D: + /* GL_TEXTURE_MAG_FILTER defaults to GL_LINEAR, no need to set it */ + GE( ctx, glTexParameteri (gl_target, + GL_TEXTURE_MIN_FILTER, + GL_LINEAR) ); + break; - switch (gl_target) - { - case GL_TEXTURE_2D: - case GL_TEXTURE_3D: - /* GL_TEXTURE_MAG_FILTER defaults to GL_LINEAR, no need to set it */ - GE( ctx, glTexParameteri (gl_target, - GL_TEXTURE_MIN_FILTER, - GL_LINEAR) ); - break; + case GL_TEXTURE_RECTANGLE_ARB: + /* Texture rectangles already default to GL_LINEAR so nothing + needs to be done */ + break; - case GL_TEXTURE_RECTANGLE_ARB: - /* Texture rectangles already default to GL_LINEAR so nothing - needs to be done */ - break; - - default: - g_assert_not_reached(); - } + default: + g_assert_not_reached(); } + + /* If the driver doesn't support alpha textures directly then we'll + * fake them by setting the swizzle parameters */ + if (internal_format == COGL_PIXEL_FORMAT_A_8 && + (ctx->private_feature_flags & (COGL_PRIVATE_FEATURE_ALPHA_TEXTURES | + COGL_PRIVATE_FEATURE_TEXTURE_SWIZZLE)) == + COGL_PRIVATE_FEATURE_TEXTURE_SWIZZLE) + { + static const GLint red_swizzle[] = { GL_ZERO, GL_ZERO, GL_ZERO, GL_RED }; + + GE( ctx, glTexParameteriv (gl_target, + GL_TEXTURE_SWIZZLE_RGBA, + red_swizzle) ); + } + + return tex; } /* OpenGL - unlike GLES - can upload a sub region of pixel data from a larger diff --git a/cogl/driver/gl/gles/cogl-driver-gles.c b/cogl/driver/gl/gles/cogl-driver-gles.c index ddd9b530b..414e3f90a 100644 --- a/cogl/driver/gl/gles/cogl-driver-gles.c +++ b/cogl/driver/gl/gles/cogl-driver-gles.c @@ -271,7 +271,8 @@ _cogl_driver_update_features (CoglContext *context, COGL_PRIVATE_FEATURE_BUILTIN_POINT_SIZE_UNIFORM); private_flags |= (COGL_PRIVATE_FEATURE_VBOS | - COGL_PRIVATE_FEATURE_ANY_GL); + COGL_PRIVATE_FEATURE_ANY_GL | + COGL_PRIVATE_FEATURE_ALPHA_TEXTURES); /* Both GLES 1.1 and GLES 2.0 support point sprites in core */ flags |= COGL_FEATURE_POINT_SPRITE; diff --git a/cogl/driver/gl/gles/cogl-texture-driver-gles.c b/cogl/driver/gl/gles/cogl-texture-driver-gles.c index af95c60e8..b42d0fb09 100644 --- a/cogl/driver/gl/gles/cogl-texture-driver-gles.c +++ b/cogl/driver/gl/gles/cogl-texture-driver-gles.c @@ -64,34 +64,32 @@ #define GL_UNPACK_SKIP_PIXELS 0x0CF4 #endif -static void +static GLuint _cogl_texture_driver_gen (CoglContext *ctx, GLenum gl_target, - GLsizei n, - GLuint *textures) + CoglPixelFormat internal_format) { - unsigned int i; + GLuint tex; - GE (ctx, glGenTextures (n, textures)); + GE (ctx, glGenTextures (1, &tex)); - for (i = 0; i < n; i++) + _cogl_bind_gl_texture_transient (gl_target, tex, FALSE); + + switch (gl_target) { - _cogl_bind_gl_texture_transient (gl_target, textures[i], FALSE); + case GL_TEXTURE_2D: + case GL_TEXTURE_3D: + /* GL_TEXTURE_MAG_FILTER defaults to GL_LINEAR, no need to set it */ + GE( ctx, glTexParameteri (gl_target, + GL_TEXTURE_MIN_FILTER, + GL_LINEAR) ); + break; - switch (gl_target) - { - case GL_TEXTURE_2D: - case GL_TEXTURE_3D: - /* GL_TEXTURE_MAG_FILTER defaults to GL_LINEAR, no need to set it */ - GE( ctx, glTexParameteri (gl_target, - GL_TEXTURE_MIN_FILTER, - GL_LINEAR) ); - break; - - default: - g_assert_not_reached(); - } + default: + g_assert_not_reached(); } + + return tex; } static void