[PATCH] YUV textures on cards having no GL_ARB_texture_rectangle stretched horizontally

SDL Development
1

When graphic card has no GL_ARB_texture_rectangle YUV textures mapped with SDL_RenderCopy are stretched 2x horizontally, so only left half of texture is visible. This is due:
data->texw = (GLfloat) (texture->w) / texture_w;
data->texh = (GLfloat) texture->h / texture_h;
But afterwards texture_w /= 2 for YUV texture, but data->texw stays as it was before, while it should be multiplied 2x.

This bug can be seen in any program setting env variables: GL_APPLE_ycbcr_422=0 GL_EXT_texture_rectangle=0 GL_ARB_texture_rectangle=0

Here’s a patch:

Index: src/video/SDL_renderer_gl.c===================================================================
— src/video/SDL_renderer_gl.c (revision 5541)
+++ src/video/SDL_renderer_gl.c (working copy)
@@ -830,10 +830,13 @@
/* YUV formats use RGBA but are really two bytes per pixel */
if (internalFormat == GL_RGBA && bytes_per_pixel(texture->format) < 4) {
data->HACK_RYAN_FIXME = 2;

  •    texture_w /= 2;

  •    if (data->type == GL_TEXTURE_2D) {

  •        data->texw *= 2.0f;

  •    }
    } else {
    data->HACK_RYAN_FIXME = 1;
    }

  • texture_w /= data->HACK_RYAN_FIXME;

    data->format = format;
    data->formattype = type;

Regards,

Adam

2

Thanks, this patch is in subversion! :)On Tue, Feb 9, 2010 at 5:11 AM, Adam Strzelecki wrote:

When graphic card has no GL_ARB_texture_rectangle YUV textures mapped with SDL_RenderCopy are stretched 2x horizontally, so only left half of texture is visible. This is due:
? ? ? ?data->texw = (GLfloat) (texture->w) / texture_w;
? ? ? ?data->texh = (GLfloat) texture->h / texture_h;
But afterwards texture_w /= 2 for YUV texture, but data->texw stays as it was before, while it should be multiplied 2x.

This bug can be seen in any program setting env variables: GL_APPLE_ycbcr_422=0 GL_EXT_texture_rectangle=0 GL_ARB_texture_rectangle=0

Here’s a patch:

Index: src/video/SDL_renderer_gl.c

— src/video/SDL_renderer_gl.c (revision 5541)
+++ src/video/SDL_renderer_gl.c (working copy)
@@ -830,10 +830,13 @@
? ? /* YUV formats use RGBA but are really two bytes per pixel */
? ? if (internalFormat == GL_RGBA && bytes_per_pixel(texture->format) < 4) {
? ? ? ? data->HACK_RYAN_FIXME = 2;

  • ? ? ? ?texture_w /= 2;
  • ? ? ? ?if (data->type == GL_TEXTURE_2D) {
  • ? ? ? ? ? ?data->texw *= 2.0f;
  • ? ? ? ?}
    ? ? } else {
    ? ? ? ? data->HACK_RYAN_FIXME = 1;
    ? ? }
  • ? ?texture_w /= data->HACK_RYAN_FIXME;

? ? data->format = format;
? ? data->formattype = type;

Regards,

Adam

SDL mailing list
SDL at lists.libsdl.org
http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org

–
-Sam Lantinga, Founder and President, Galaxy Gameworks LLC