[Mesa-dev] [PATCH] i965/fs: Implement GL_CLAMP behavior on texture rectangles on gen6+.

[Ian Romanick]

On 02/04/2012 05:24 AM, Eric Anholt wrote:
> We were doing saturate-based clamping on the [0,width] or [0,height]
> coordinate, which meant only the first pixel was addressable.
>
> Fixes piglit ARB_texture_rectangle/texwrap-RECT-bordercolor

Tag this for stable branches too.

Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>

> ---
>
> I feel dirty.
>
>   src/mesa/drivers/dri/i965/brw_fs_visitor.cpp |   54 +++++++++++++++++++++++--
>   1 files changed, 49 insertions(+), 5 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
> index e57e175..ea8cd37 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
> @@ -1079,12 +1079,18 @@ fs_visitor::visit(ir_texture *ir)
>      /* Should be lowered by do_lower_texture_projection */
>      assert(!ir->projector);
>
> +   bool needs_gl_clamp = true;
> +
> +   fs_reg scale_x, scale_y;
> +
>      /* The 965 requires the EU to do the normalization of GL rectangle
>       * texture coordinates.  We use the program parameter state
>       * tracking to get the scaling factor.
>       */
> -   if (intel->gen<  6&&
> -       ir->sampler->type->sampler_dimensionality == GLSL_SAMPLER_DIM_RECT) {
> +   if (ir->sampler->type->sampler_dimensionality == GLSL_SAMPLER_DIM_RECT&&
> +       (intel->gen<  6 ||
> +	(intel->gen>= 6&&  (c->key.tex.gl_clamp_mask[0]&  (1<<  sampler) ||
> +			     c->key.tex.gl_clamp_mask[1]&  (1<<  sampler))))) {
>         struct gl_program_parameter_list *params = c->fp->program.Base.Parameters;
>         int tokens[STATE_LENGTH] = {
>   	 STATE_INTERNAL,
> @@ -1105,8 +1111,9 @@ fs_visitor::visit(ir_texture *ir)
>         c->prog_data.param_convert[c->prog_data.nr_params + 1] =
>   	 PARAM_NO_CONVERT;
>
> -      fs_reg scale_x = fs_reg(UNIFORM, c->prog_data.nr_params);
> -      fs_reg scale_y = fs_reg(UNIFORM, c->prog_data.nr_params + 1);
> +      scale_x = fs_reg(UNIFORM, c->prog_data.nr_params);
> +      scale_y = fs_reg(UNIFORM, c->prog_data.nr_params + 1);
> +
>         GLuint index = _mesa_add_state_reference(params,
>   					       (gl_state_index *)tokens);
>
> @@ -1116,7 +1123,14 @@ fs_visitor::visit(ir_texture *ir)
>         this->param_index[c->prog_data.nr_params] = index;
>         this->param_offset[c->prog_data.nr_params] = 1;
>         c->prog_data.nr_params++;
> +   }
>
> +   /* The 965 requires the EU to do the normalization of GL rectangle
> +    * texture coordinates.  We use the program parameter state
> +    * tracking to get the scaling factor.
> +    */
> +   if (intel->gen<  6&&
> +       ir->sampler->type->sampler_dimensionality == GLSL_SAMPLER_DIM_RECT) {
>         fs_reg dst = fs_reg(this, ir->coordinate->type);
>         fs_reg src = coordinate;
>         coordinate = dst;
> @@ -1125,9 +1139,39 @@ fs_visitor::visit(ir_texture *ir)
>         dst.reg_offset++;
>         src.reg_offset++;
>         emit(BRW_OPCODE_MUL, dst, src, scale_y);
> +   } else if (ir->sampler->type->sampler_dimensionality == GLSL_SAMPLER_DIM_RECT) {
> +      /* On gen6+, the sampler handles the rectangle coordinates
> +       * natively, without needing rescaling.  But that means we have
> +       * to do GL_CLAMP clamping at the [0, width], [0, height] scale,
> +       * not [0, 1] like the default case below.
> +       */
> +      needs_gl_clamp = false;
> +
> +      for (int i = 0; i<  2; i++) {
> +	 if (c->key.tex.gl_clamp_mask[i]&  (1<<  sampler)) {
> +	    fs_reg chan = coordinate;
> +	    chan.reg_offset += i;
> +
> +	    inst = emit(BRW_OPCODE_SEL, chan, chan, brw_imm_f(0.0));
> +	    inst->conditional_mod = BRW_CONDITIONAL_G;
> +
> +	    /* Our parameter comes in as 1.0/width or 1.0/height,
> +	     * because that's what people normally want for doing
> +	     * texture rectangle handling.  We need width or height
> +	     * for clamping, but we don't care enough to make a new
> +	     * parameter type, so just invert back.
> +	     */
> +	    fs_reg limit = fs_reg(this, glsl_type::float_type);
> +	    emit(BRW_OPCODE_MOV, limit, i == 0 ? scale_x : scale_y);
> +	    emit(SHADER_OPCODE_RCP, limit, limit);
> +
> +	    inst = emit(BRW_OPCODE_SEL, chan, chan, limit);
> +	    inst->conditional_mod = BRW_CONDITIONAL_L;
> +	 }
> +      }
>      }
>
> -   if (ir->coordinate) {
> +   if (ir->coordinate&&  needs_gl_clamp) {
>         for (int i = 0; i<  MIN2(ir->coordinate->type->vector_elements, 3); i++) {
>   	 if (c->key.tex.gl_clamp_mask[i]&  (1<<  sampler)) {
>   	    fs_reg chan = coordinate;