[Piglit] [PATCH 1/2] util: provide way to read a texture in ES compatible way

[Brian Paul]

It looks like this will bypass glGetTexImage even for desktop GL.  We 
may loose some test coverage because of that.  Could we do the 
fbo/ReadPixels work-around only on ES?

One indentation issue below.

-Brian


On 05/18/2018 02:29 AM, Tapani Pälli wrote:
> Any comments? I'm planning to push this in soon to be able to push 
> oes_texture_view changes to Mesa.
> 
> On 05/11/2018 01:17 PM, Tapani Pälli wrote:
>> Implementation supports GL_TEXTURE_2D, GL_TEXTURE_2D_ARRAY
>> and affects following functions:
>>
>>     - piglit_probe_texel_rect_rgba
>>     - piglit_probe_texel_volume_rgba
>>
>> Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
>> ---
>>   tests/util/piglit-util-gl.c | 109 
>> ++++++++++++++++++++++++++++++++++++++++++--
>>   1 file changed, 105 insertions(+), 4 deletions(-)
>>
>> diff --git a/tests/util/piglit-util-gl.c b/tests/util/piglit-util-gl.c
>> index 2443be03e..f6a83e717 100644
>> --- a/tests/util/piglit-util-gl.c
>> +++ b/tests/util/piglit-util-gl.c
>> @@ -1882,6 +1882,99 @@ piglit_probe_image_ubyte(int x, int y, int w, 
>> int h, GLenum format,
>>       return 1;
>>   }
>> +static GLuint
>> +create_fbo_from_texture(GLenum target, GLint texture, GLint level, 
>> GLint layer)
>> +{
>> +    GLuint fbo;
>> +
>> +    glGenFramebuffers(1, &fbo);
>> +    glBindFramebuffer(GL_FRAMEBUFFER, fbo);
>> +
>> +    if (layer > 0) {
>> +        glFramebufferTextureLayer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
>> +                      texture, level, layer);
>> +    } else {
>> +        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
>> +                       target, texture, level);
>> +    }
>> +
>> +    assert(glCheckFramebufferStatus(GL_FRAMEBUFFER) ==
>> +           GL_FRAMEBUFFER_COMPLETE);
>> +    return fbo;
>> +}
>> +
>> +static GLenum
>> +binding_from_target(GLenum target)
>> +{
>> +    switch (target)    {
>> +    case GL_TEXTURE_2D:
>> +        return GL_TEXTURE_BINDING_2D;
>> +    case GL_TEXTURE_2D_ARRAY:
>> +        return GL_TEXTURE_BINDING_2D_ARRAY;
>> +    default:
>> +        fprintf(stderr, "%s: unsupported target 0x%x\n",
>> +            __func__, target);
>> +        return 0;
>> +    }
>> +}
>> +
>> +/**
>> + * Read texels in OpenGL ES compatible way.
>> + *
>> + * Currently bound texture is attached to a framebuffer object and
>> + * contents are read using glReadPixels. Supported targets are
>> + * GL_TEXTURE_2D, GL_TEXTURE_2D_ARRAY.
>> + */
>> +static GLfloat *
>> +read_texture(int target, int level, int x, int y, int layer, int w, 
>> int h)
>> +{
>> +    GLint width, height, depth;
>> +    GLint current_read_fbo, current_draw_fbo, current_texture;
>> +    GLenum binding = binding_from_target(target);
>> +    unsigned char *buf;
>> +    GLfloat *buffer;
>> +    unsigned offset;
>> +
>> +    assert(binding != 0);
>> +
>> +    glGetIntegerv(binding, &current_texture);
>> +    glGetIntegerv(GL_READ_FRAMEBUFFER_BINDING, &current_read_fbo);
>> +    glGetIntegerv(GL_DRAW_FRAMEBUFFER_BINDING, &current_draw_fbo);
>> +
>> +    assert(target == GL_TEXTURE_2D || target == GL_TEXTURE_2D_ARRAY);
>> +
>> +    glGetTexLevelParameteriv(target, level, GL_TEXTURE_WIDTH, &width);
>> +    glGetTexLevelParameteriv(target, level, GL_TEXTURE_HEIGHT, &height);
>> +    glGetTexLevelParameteriv(target, level, GL_TEXTURE_DEPTH, &depth);
>> +
>> +    buffer = malloc(width * height * depth * 4 * sizeof(GLfloat));
>> +    buf = malloc(width * height * depth * 4 * sizeof(unsigned char));
>> +
>> +    GLuint fbo =
>> +        create_fbo_from_texture(target, current_texture, level, layer);
>> +    assert(fbo != 0);
>> +
>> +    /* Offset to the layer we are expected to read. */
>> +    offset = layer * (width * height * 4);
>> +
>> +    glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE,
>> +             buf + offset);
>> +
>> +    for (unsigned k = offset; k < offset + width * height * 4; k++)
>> +        buffer[k] = ((float) buf[k]) / 255.0;
>> +
>> +    free(buf);
>> +
>> +    glDeleteFramebuffers(1, &fbo);
>> +
>> +    /* Restore FBO state. */
>> +    glBindFramebuffer(GL_READ_FRAMEBUFFER, current_read_fbo);
>> +    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, current_draw_fbo);
>> +
>> +    return buffer;
>> +}
>> +
>> +
>>   /**
>>    * Read a texel rectangle from the given location and compare its 
>> RGB value to
>>    * the given expected values.
>> @@ -1957,9 +2050,13 @@ int piglit_probe_texel_rect_rgba(int target, 
>> int level, int x, int y,
>>       glGetTexLevelParameteriv(target, level, GL_TEXTURE_WIDTH, &width);
>>       glGetTexLevelParameteriv(target, level, GL_TEXTURE_HEIGHT, 
>> &height);
>> -    buffer = malloc(width * height * 4 * sizeof(GLfloat));
>> -    glGetTexImage(target, level, GL_RGBA, GL_FLOAT, buffer);
>> +    if (target == GL_TEXTURE_2D) {
>> +        buffer = read_texture(target, level, x, y, 0, w, h);
>> +    } else {
>> +        buffer = malloc(width * height * 4 * sizeof(GLfloat));
>> +        glGetTexImage(target, level, GL_RGBA, GL_FLOAT, buffer);
>> +    }
>>       assert(x >= 0);
>>       assert(y >= 0);
>> @@ -2021,9 +2118,13 @@ int piglit_probe_texel_volume_rgba(int target, 
>> int level, int x, int y, int z,
>>       glGetTexLevelParameteriv(target, level, GL_TEXTURE_WIDTH, &width);
>>       glGetTexLevelParameteriv(target, level, GL_TEXTURE_HEIGHT, 
>> &height);
>>       glGetTexLevelParameteriv(target, level, GL_TEXTURE_DEPTH, &depth);
>> -    buffer = malloc(width * height * depth * 4 * sizeof(GLfloat));
>> -    glGetTexImage(target, level, GL_RGBA, GL_FLOAT, buffer);
>> +    if (target == GL_TEXTURE_2D || GL_TEXTURE_2D_ARRAY) {
>> +        buffer = read_texture(target, level, x, y, z, w, h);
>> +        } else {

Fix indentation.

>> +        buffer = malloc(width * height * depth * 4 * sizeof(GLfloat));
>> +        glGetTexImage(target, level, GL_RGBA, GL_FLOAT, buffer);
>> +    }
>>       assert(x >= 0);
>>       assert(y >= 0);
>>
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