Function init_compute_averages

Source/astcenc_compute_variance.cpp:507–556

See header for documentation. */

/* See header for documentation. */
size_t init_compute_averages(
	const astcenc_image& img,
	size_t alpha_kernel_radius,
	const astcenc_swizzle& swz,
	avg_args& ag
) {
	size_t size_x = img.dim_x;
	size_t size_y = img.dim_y;
	size_t size_z = img.dim_z;

	// Compute maximum block size and from that the working memory buffer size
	size_t kernel_radius = alpha_kernel_radius;
	size_t kerneldim = 2 * kernel_radius + 1;

	bool have_z = size_z > 1;
	size_t max_blk_size_xy = have_z ? 16u : 32u;

	size_t max_blk_size_z_lim = have_z ? 16u : 1u;
	size_t max_blk_size_z = astc::min(size_z, max_blk_size_z_lim);

	size_t max_padsize_xy = max_blk_size_xy + kerneldim;
	size_t max_padsize_z = max_blk_size_z + (have_z ? kerneldim : 0);

	// Perform block-wise averages calculations across the image
	// Initialize fields which are not populated until later
	ag.arg.size_x = 0;
	ag.arg.size_y = 0;
	ag.arg.size_z = 0;
	ag.arg.offset_x = 0;
	ag.arg.offset_y = 0;
	ag.arg.offset_z = 0;
	ag.arg.work_memory = nullptr;

	ag.arg.img = &img;
	ag.arg.swz = swz;
	ag.arg.have_z = have_z;
	ag.arg.alpha_kernel_radius = alpha_kernel_radius;

	ag.img_size_x = size_x;
	ag.img_size_y = size_y;
	ag.img_size_z = size_z;
	ag.blk_size_xy = max_blk_size_xy;
	ag.blk_size_z = max_blk_size_z;
	ag.work_memory_size = 2 * max_padsize_xy * max_padsize_xy * max_padsize_z;

	// The parallel task count
	size_t tasks_z = astc::get_block_count_safe(size_z, max_blk_size_z);
	size_t tasks_y = astc::get_block_count_safe(size_y, max_blk_size_xy);
	return tasks_z * tasks_y;
}

#endif