src/mesa/state_tracker/st_cb_clear.c - third_party/mesa - Git at Google

 /**************************************************************************
  *
  * Copyright 2007 VMware, Inc.
  * All Rights Reserved.
  * Copyright 2009 VMware, Inc.  All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the
  * "Software"), to deal in the Software without restriction, including
  * without limitation the rights to use, copy, modify, merge, publish,
  * distribute, sub license, and/or sell copies of the Software, and to
  * permit persons to whom the Software is furnished to do so, subject to
  * the following conditions:
  *
  * The above copyright notice and this permission notice (including the
  * next paragraph) shall be included in all copies or substantial portions
  * of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
  * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  *
  **************************************************************************/

  /*
   * Authors:
   *   Keith Whitwell <keithw@vmware.com>
   *   Brian Paul
   *   Michel Dänzer
   */

 #include "main/glheader.h"
 #include "main/accum.h"
 #include "main/formats.h"
 #include "main/framebuffer.h"
 #include "main/macros.h"
 #include "main/glformats.h"
 #include "program/prog_instruction.h"
 #include "st_context.h"
 #include "st_atom.h"
 #include "st_cb_bitmap.h"
 #include "st_cb_clear.h"
 #include "st_cb_fbo.h"
 #include "st_draw.h"
 #include "st_format.h"
 #include "st_program.h"

 #include "pipe/p_context.h"
 #include "pipe/p_shader_tokens.h"
 #include "pipe/p_state.h"
 #include "pipe/p_defines.h"
 #include "util/u_format.h"
 #include "util/u_inlines.h"
 #include "util/u_simple_shaders.h"

 #include "cso_cache/cso_context.h"


 /**
  * Do per-context initialization for glClear.
  */
 void
 st_init_clear(struct st_context *st)
 {
    memset(&st->clear, 0, sizeof(st->clear));

    st->clear.raster.half_pixel_center = 1;
    st->clear.raster.bottom_edge_rule = 1;
    st->clear.raster.depth_clip = 1;
 }


 /**
  * Free per-context state for glClear.
  */
 void
 st_destroy_clear(struct st_context *st)
 {
    if (st->clear.fs) {
       cso_delete_fragment_shader(st->cso_context, st->clear.fs);
       st->clear.fs = NULL;
    }
    if (st->clear.vs) {
       cso_delete_vertex_shader(st->cso_context, st->clear.vs);
       st->clear.vs = NULL;
    }
    if (st->clear.vs_layered) {
       cso_delete_vertex_shader(st->cso_context, st->clear.vs_layered);
       st->clear.vs_layered = NULL;
    }
    if (st->clear.gs_layered) {
       cso_delete_geometry_shader(st->cso_context, st->clear.gs_layered);
       st->clear.gs_layered = NULL;
    }
 }


 /**
  * Helper function to set the fragment shaders.
  */
 static inline void
 set_fragment_shader(struct st_context *st)
 {
    if (!st->clear.fs)
       st->clear.fs =
          util_make_fragment_passthrough_shader(st->pipe, TGSI_SEMANTIC_GENERIC,
                                                TGSI_INTERPOLATE_CONSTANT,
                                                TRUE);

    cso_set_fragment_shader_handle(st->cso_context, st->clear.fs);
 }


 /**
  * Helper function to set the vertex shader.
  */
 static inline void
 set_vertex_shader(struct st_context *st)
 {
    /* vertex shader - still required to provide the linkage between
     * fragment shader input semantics and vertex_element/buffers.
     */
    if (!st->clear.vs)
    {
       const uint semantic_names[] = { TGSI_SEMANTIC_POSITION,
                                       TGSI_SEMANTIC_GENERIC };
       const uint semantic_indexes[] = { 0, 0 };
       st->clear.vs = util_make_vertex_passthrough_shader(st->pipe, 2,
                                                          semantic_names,
                                                          semantic_indexes,
                                                          FALSE);
    }

    cso_set_vertex_shader_handle(st->cso_context, st->clear.vs);
    cso_set_geometry_shader_handle(st->cso_context, NULL);
 }


 static void
 set_vertex_shader_layered(struct st_context *st)
 {
    struct pipe_context *pipe = st->pipe;

    if (!pipe->screen->get_param(pipe->screen, PIPE_CAP_TGSI_INSTANCEID)) {
       assert(!"Got layered clear, but VS instancing is unsupported");
       set_vertex_shader(st);
       return;
    }

    if (!st->clear.vs_layered) {
       bool vs_layer =
          pipe->screen->get_param(pipe->screen, PIPE_CAP_TGSI_VS_LAYER_VIEWPORT);
       if (vs_layer) {
          st->clear.vs_layered = util_make_layered_clear_vertex_shader(pipe);
       } else {
          st->clear.vs_layered = util_make_layered_clear_helper_vertex_shader(pipe);
          st->clear.gs_layered = util_make_layered_clear_geometry_shader(pipe);
       }
    }

    cso_set_vertex_shader_handle(st->cso_context, st->clear.vs_layered);
    cso_set_geometry_shader_handle(st->cso_context, st->clear.gs_layered);
 }


 /**
  * Do glClear by drawing a quadrilateral.
  * The vertices of the quad will be computed from the
  * ctx->DrawBuffer->_X/Ymin/max fields.
  */
 static void
 clear_with_quad(struct gl_context *ctx, unsigned clear_buffers)
 {
    struct st_context *st = st_context(ctx);
    struct cso_context *cso = st->cso_context;
    const struct gl_framebuffer *fb = ctx->DrawBuffer;
    const GLfloat fb_width = (GLfloat) fb->Width;
    const GLfloat fb_height = (GLfloat) fb->Height;

    _mesa_update_draw_buffer_bounds(ctx, ctx->DrawBuffer);

    const GLfloat x0 = (GLfloat) ctx->DrawBuffer->_Xmin / fb_width * 2.0f - 1.0f;
    const GLfloat x1 = (GLfloat) ctx->DrawBuffer->_Xmax / fb_width * 2.0f - 1.0f;
    const GLfloat y0 = (GLfloat) ctx->DrawBuffer->_Ymin / fb_height * 2.0f - 1.0f;
    const GLfloat y1 = (GLfloat) ctx->DrawBuffer->_Ymax / fb_height * 2.0f - 1.0f;
    unsigned num_layers = st->state.fb_num_layers;

    /*
    printf("%s %s%s%s %f,%f %f,%f\n", __func__,
 	  color ? "color, " : "",
 	  depth ? "depth, " : "",
 	  stencil ? "stencil" : "",
 	  x0, y0,
 	  x1, y1);
    */

    cso_save_state(cso, (CSO_BIT_BLEND |
                         CSO_BIT_STENCIL_REF |
                         CSO_BIT_DEPTH_STENCIL_ALPHA |
                         CSO_BIT_RASTERIZER |
                         CSO_BIT_SAMPLE_MASK |
                         CSO_BIT_MIN_SAMPLES |
                         CSO_BIT_VIEWPORT |
                         CSO_BIT_STREAM_OUTPUTS |
                         CSO_BIT_VERTEX_ELEMENTS |
                         CSO_BIT_AUX_VERTEX_BUFFER_SLOT |
                         CSO_BIT_PAUSE_QUERIES |
                         CSO_BITS_ALL_SHADERS));

    /* blend state: RGBA masking */
    {
       struct pipe_blend_state blend;
       memset(&blend, 0, sizeof(blend));
       if (clear_buffers & PIPE_CLEAR_COLOR) {
          int num_buffers = ctx->Extensions.EXT_draw_buffers2 ?
                            ctx->DrawBuffer->_NumColorDrawBuffers : 1;
          int i;

          blend.independent_blend_enable = num_buffers > 1;

          for (i = 0; i < num_buffers; i++) {
             if (!(clear_buffers & (PIPE_CLEAR_COLOR0 << i)))
                continue;

             if (ctx->Color.ColorMask[i][0])
                blend.rt[i].colormask |= PIPE_MASK_R;
             if (ctx->Color.ColorMask[i][1])
                blend.rt[i].colormask |= PIPE_MASK_G;
             if (ctx->Color.ColorMask[i][2])
                blend.rt[i].colormask |= PIPE_MASK_B;
             if (ctx->Color.ColorMask[i][3])
                blend.rt[i].colormask |= PIPE_MASK_A;
          }

          if (ctx->Color.DitherFlag)
             blend.dither = 1;
       }
       cso_set_blend(cso, &blend);
    }

    /* depth_stencil state: always pass/set to ref value */
    {
       struct pipe_depth_stencil_alpha_state depth_stencil;
       memset(&depth_stencil, 0, sizeof(depth_stencil));
       if (clear_buffers & PIPE_CLEAR_DEPTH) {
          depth_stencil.depth.enabled = 1;
          depth_stencil.depth.writemask = 1;
          depth_stencil.depth.func = PIPE_FUNC_ALWAYS;
       }

       if (clear_buffers & PIPE_CLEAR_STENCIL) {
          struct pipe_stencil_ref stencil_ref;
          memset(&stencil_ref, 0, sizeof(stencil_ref));
          depth_stencil.stencil[0].enabled = 1;
          depth_stencil.stencil[0].func = PIPE_FUNC_ALWAYS;
          depth_stencil.stencil[0].fail_op = PIPE_STENCIL_OP_REPLACE;
          depth_stencil.stencil[0].zpass_op = PIPE_STENCIL_OP_REPLACE;
          depth_stencil.stencil[0].zfail_op = PIPE_STENCIL_OP_REPLACE;
          depth_stencil.stencil[0].valuemask = 0xff;
          depth_stencil.stencil[0].writemask = ctx->Stencil.WriteMask[0] & 0xff;
          stencil_ref.ref_value[0] = ctx->Stencil.Clear;
          cso_set_stencil_ref(cso, &stencil_ref);
       }

       cso_set_depth_stencil_alpha(cso, &depth_stencil);
    }

    cso_set_vertex_elements(cso, 2, st->util_velems);
    cso_set_stream_outputs(cso, 0, NULL, NULL);
    cso_set_sample_mask(cso, ~0);
    cso_set_min_samples(cso, 1);
    cso_set_rasterizer(cso, &st->clear.raster);

    /* viewport state: viewport matching window dims */
    cso_set_viewport_dims(st->cso_context, fb_width, fb_height,
                          st_fb_orientation(fb) == Y_0_TOP);

    set_fragment_shader(st);
    cso_set_tessctrl_shader_handle(cso, NULL);
    cso_set_tesseval_shader_handle(cso, NULL);

    if (num_layers > 1)
       set_vertex_shader_layered(st);
    else
       set_vertex_shader(st);

    /* draw quad matching scissor rect.
     *
     * Note: if we're only clearing depth/stencil we still setup vertices
     * with color, but they'll be ignored.
     *
     * We can't translate the clear color to the colorbuffer format,
     * because different colorbuffers may have different formats.
     */
    if (!st_draw_quad(st, x0, y0, x1, y1,
                      ctx->Depth.Clear * 2.0f - 1.0f,
                      0.0f, 0.0f, 0.0f, 0.0f,
                      (const float *) &ctx->Color.ClearColor.f,
                      num_layers)) {
       _mesa_error(ctx, GL_OUT_OF_MEMORY, "glClear");
    }

    /* Restore pipe state */
    cso_restore_state(cso);
 }


 /**
  * Return if the scissor must be enabled during the clear.
  */
 static inline GLboolean
 is_scissor_enabled(struct gl_context *ctx, struct gl_renderbuffer *rb)
 {
    const struct gl_scissor_rect *scissor = &ctx->Scissor.ScissorArray[0];

    return (ctx->Scissor.EnableFlags & 1) &&
           (scissor->X > 0 ||
            scissor->Y > 0 ||
            scissor->X + scissor->Width < (int)rb->Width ||
            scissor->Y + scissor->Height < (int)rb->Height);
 }

 /**
  * Return if window rectangles must be enabled during the clear.
  */
 static inline bool
 is_window_rectangle_enabled(struct gl_context *ctx)
 {
    if (ctx->DrawBuffer == ctx->WinSysDrawBuffer)
       return false;
    return ctx->Scissor.NumWindowRects > 0 ||
       ctx->Scissor.WindowRectMode == GL_INCLUSIVE_EXT;
 }


 /**
  * Return if all of the color channels are masked.
  */
 static inline GLboolean
 is_color_disabled(struct gl_context *ctx, int i)
 {
    return !ctx->Color.ColorMask[i][0] &&
           !ctx->Color.ColorMask[i][1] &&
           !ctx->Color.ColorMask[i][2] &&
           !ctx->Color.ColorMask[i][3];
 }


 /**
  * Return if any of the color channels are masked.
  */
 static inline GLboolean
 is_color_masked(struct gl_context *ctx, int i)
 {
    return !ctx->Color.ColorMask[i][0] ||
           !ctx->Color.ColorMask[i][1] ||
           !ctx->Color.ColorMask[i][2] ||
           !ctx->Color.ColorMask[i][3];
 }


 /**
  * Return if all of the stencil bits are masked.
  */
 static inline GLboolean
 is_stencil_disabled(struct gl_context *ctx, struct gl_renderbuffer *rb)
 {
    const GLuint stencilMax = 0xff;

    assert(_mesa_get_format_bits(rb->Format, GL_STENCIL_BITS) > 0);
    return (ctx->Stencil.WriteMask[0] & stencilMax) == 0;
 }


 /**
  * Return if any of the stencil bits are masked.
  */
 static inline GLboolean
 is_stencil_masked(struct gl_context *ctx, struct gl_renderbuffer *rb)
 {
    const GLuint stencilMax = 0xff;

    assert(_mesa_get_format_bits(rb->Format, GL_STENCIL_BITS) > 0);
    return (ctx->Stencil.WriteMask[0] & stencilMax) != stencilMax;
 }


 /**
  * Called via ctx->Driver.Clear()
  */
 static void
 st_Clear(struct gl_context *ctx, GLbitfield mask)
 {
    struct st_context *st = st_context(ctx);
    struct gl_renderbuffer *depthRb
       = ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer;
    struct gl_renderbuffer *stencilRb
       = ctx->DrawBuffer->Attachment[BUFFER_STENCIL].Renderbuffer;
    GLbitfield quad_buffers = 0x0;
    GLbitfield clear_buffers = 0x0;
    GLuint i;

    st_flush_bitmap_cache(st);
    st_invalidate_readpix_cache(st);

    /* This makes sure the pipe has the latest scissor, etc values */
    st_validate_state(st, ST_PIPELINE_CLEAR);

    if (mask & BUFFER_BITS_COLOR) {
       for (i = 0; i < ctx->DrawBuffer->_NumColorDrawBuffers; i++) {
          GLint b = ctx->DrawBuffer->_ColorDrawBufferIndexes[i];

          if (b >= 0 && mask & (1 << b)) {
             struct gl_renderbuffer *rb
                = ctx->DrawBuffer->Attachment[b].Renderbuffer;
             struct st_renderbuffer *strb = st_renderbuffer(rb);
             int colormask_index = ctx->Extensions.EXT_draw_buffers2 ? i : 0;

             if (!strb || !strb->surface)
                continue;

             if (is_color_disabled(ctx, colormask_index))
                continue;

             if (is_scissor_enabled(ctx, rb) ||
                 is_window_rectangle_enabled(ctx) ||
                 is_color_masked(ctx, colormask_index))
                quad_buffers |= PIPE_CLEAR_COLOR0 << i;
             else
                clear_buffers |= PIPE_CLEAR_COLOR0 << i;
          }
       }
    }

    if (mask & BUFFER_BIT_DEPTH) {
       struct st_renderbuffer *strb = st_renderbuffer(depthRb);

       if (strb->surface && ctx->Depth.Mask) {
          if (is_scissor_enabled(ctx, depthRb) ||
              is_window_rectangle_enabled(ctx))
             quad_buffers |= PIPE_CLEAR_DEPTH;
          else
             clear_buffers |= PIPE_CLEAR_DEPTH;
       }
    }
    if (mask & BUFFER_BIT_STENCIL) {
       struct st_renderbuffer *strb = st_renderbuffer(stencilRb);

       if (strb->surface && !is_stencil_disabled(ctx, stencilRb)) {
          if (is_scissor_enabled(ctx, stencilRb) ||
              is_window_rectangle_enabled(ctx) ||
              is_stencil_masked(ctx, stencilRb))
             quad_buffers |= PIPE_CLEAR_STENCIL;
          else
             clear_buffers |= PIPE_CLEAR_STENCIL;
       }
    }

    /* Always clear depth and stencil together.
     * This can only happen when the stencil writemask is not a full mask.
     */
    if (quad_buffers & PIPE_CLEAR_DEPTHSTENCIL &&
        clear_buffers & PIPE_CLEAR_DEPTHSTENCIL) {
       quad_buffers |= clear_buffers & PIPE_CLEAR_DEPTHSTENCIL;
       clear_buffers &= ~PIPE_CLEAR_DEPTHSTENCIL;
    }

    /* Only use quad-based clearing for the renderbuffers which cannot
     * use pipe->clear. We want to always use pipe->clear for the other
     * renderbuffers, because it's likely to be faster.
     */
    if (quad_buffers) {
       clear_with_quad(ctx, quad_buffers);
    }
    if (clear_buffers) {
       /* We can't translate the clear color to the colorbuffer format,
        * because different colorbuffers may have different formats.
        */
       st->pipe->clear(st->pipe, clear_buffers,
                       (union pipe_color_union*)&ctx->Color.ClearColor,
                       ctx->Depth.Clear, ctx->Stencil.Clear);
    }
    if (mask & BUFFER_BIT_ACCUM)
       _mesa_clear_accum_buffer(ctx);
 }


 void
 st_init_clear_functions(struct dd_function_table *functions)
 {
    functions->Clear = st_Clear;
 }
	/**************************************************************************
	*
	* Copyright 2007 VMware, Inc.
	* All Rights Reserved.
	* Copyright 2009 VMware, Inc. All Rights Reserved.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the
	* "Software"), to deal in the Software without restriction, including
	* without limitation the rights to use, copy, modify, merge, publish,
	* distribute, sub license, and/or sell copies of the Software, and to
	* permit persons to whom the Software is furnished to do so, subject to
	* the following conditions:
	*
	* The above copyright notice and this permission notice (including the
	* next paragraph) shall be included in all copies or substantial portions
	* of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
	* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
	* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
	* IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
	* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
	* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
	* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
	*
	**************************************************************************/

	/*
	* Authors:
	* Keith Whitwell <keithw@vmware.com>
	* Brian Paul
	* Michel Dänzer
	*/

	#include "main/glheader.h"
	#include "main/accum.h"
	#include "main/formats.h"
	#include "main/framebuffer.h"
	#include "main/macros.h"
	#include "main/glformats.h"
	#include "program/prog_instruction.h"
	#include "st_context.h"
	#include "st_atom.h"
	#include "st_cb_bitmap.h"
	#include "st_cb_clear.h"
	#include "st_cb_fbo.h"
	#include "st_draw.h"
	#include "st_format.h"
	#include "st_program.h"

	#include "pipe/p_context.h"
	#include "pipe/p_shader_tokens.h"
	#include "pipe/p_state.h"
	#include "pipe/p_defines.h"
	#include "util/u_format.h"
	#include "util/u_inlines.h"
	#include "util/u_simple_shaders.h"

	#include "cso_cache/cso_context.h"


	/**
	* Do per-context initialization for glClear.
	*/
	void
	st_init_clear(struct st_context *st)
	{
	memset(&st->clear, 0, sizeof(st->clear));

	st->clear.raster.half_pixel_center = 1;
	st->clear.raster.bottom_edge_rule = 1;
	st->clear.raster.depth_clip = 1;
	}


	/**
	* Free per-context state for glClear.
	*/
	void
	st_destroy_clear(struct st_context *st)
	{
	if (st->clear.fs) {
	cso_delete_fragment_shader(st->cso_context, st->clear.fs);
	st->clear.fs = NULL;
	}
	if (st->clear.vs) {
	cso_delete_vertex_shader(st->cso_context, st->clear.vs);
	st->clear.vs = NULL;
	}
	if (st->clear.vs_layered) {
	cso_delete_vertex_shader(st->cso_context, st->clear.vs_layered);
	st->clear.vs_layered = NULL;
	}
	if (st->clear.gs_layered) {
	cso_delete_geometry_shader(st->cso_context, st->clear.gs_layered);
	st->clear.gs_layered = NULL;
	}
	}


	/**
	* Helper function to set the fragment shaders.
	*/
	static inline void
	set_fragment_shader(struct st_context *st)
	{
	if (!st->clear.fs)
	st->clear.fs =
	util_make_fragment_passthrough_shader(st->pipe, TGSI_SEMANTIC_GENERIC,
	TGSI_INTERPOLATE_CONSTANT,
	TRUE);

	cso_set_fragment_shader_handle(st->cso_context, st->clear.fs);
	}


	/**
	* Helper function to set the vertex shader.
	*/
	static inline void
	set_vertex_shader(struct st_context *st)
	{
	/* vertex shader - still required to provide the linkage between
	* fragment shader input semantics and vertex_element/buffers.
	*/
	if (!st->clear.vs)
	{
	const uint semantic_names[] = { TGSI_SEMANTIC_POSITION,
	TGSI_SEMANTIC_GENERIC };
	const uint semantic_indexes[] = { 0, 0 };
	st->clear.vs = util_make_vertex_passthrough_shader(st->pipe, 2,
	semantic_names,
	semantic_indexes,
	FALSE);
	}

	cso_set_vertex_shader_handle(st->cso_context, st->clear.vs);
	cso_set_geometry_shader_handle(st->cso_context, NULL);
	}


	static void
	set_vertex_shader_layered(struct st_context *st)
	{
	struct pipe_context *pipe = st->pipe;

	if (!pipe->screen->get_param(pipe->screen, PIPE_CAP_TGSI_INSTANCEID)) {
	assert(!"Got layered clear, but VS instancing is unsupported");
	set_vertex_shader(st);
	return;
	}

	if (!st->clear.vs_layered) {
	bool vs_layer =
	pipe->screen->get_param(pipe->screen, PIPE_CAP_TGSI_VS_LAYER_VIEWPORT);
	if (vs_layer) {
	st->clear.vs_layered = util_make_layered_clear_vertex_shader(pipe);
	} else {
	st->clear.vs_layered = util_make_layered_clear_helper_vertex_shader(pipe);
	st->clear.gs_layered = util_make_layered_clear_geometry_shader(pipe);
	}
	}

	cso_set_vertex_shader_handle(st->cso_context, st->clear.vs_layered);
	cso_set_geometry_shader_handle(st->cso_context, st->clear.gs_layered);
	}


	/**
	* Do glClear by drawing a quadrilateral.
	* The vertices of the quad will be computed from the
	* ctx->DrawBuffer->_X/Ymin/max fields.
	*/
	static void
	clear_with_quad(struct gl_context *ctx, unsigned clear_buffers)
	{
	struct st_context *st = st_context(ctx);
	struct cso_context *cso = st->cso_context;
	const struct gl_framebuffer *fb = ctx->DrawBuffer;
	const GLfloat fb_width = (GLfloat) fb->Width;
	const GLfloat fb_height = (GLfloat) fb->Height;

	_mesa_update_draw_buffer_bounds(ctx, ctx->DrawBuffer);

	const GLfloat x0 = (GLfloat) ctx->DrawBuffer->_Xmin / fb_width * 2.0f - 1.0f;
	const GLfloat x1 = (GLfloat) ctx->DrawBuffer->_Xmax / fb_width * 2.0f - 1.0f;
	const GLfloat y0 = (GLfloat) ctx->DrawBuffer->_Ymin / fb_height * 2.0f - 1.0f;
	const GLfloat y1 = (GLfloat) ctx->DrawBuffer->_Ymax / fb_height * 2.0f - 1.0f;
	unsigned num_layers = st->state.fb_num_layers;

	/*
	printf("%s %s%s%s %f,%f %f,%f\n", __func__,
	color ? "color, " : "",
	depth ? "depth, " : "",
	stencil ? "stencil" : "",
	x0, y0,
	x1, y1);
	*/

	cso_save_state(cso, (CSO_BIT_BLEND \|
	CSO_BIT_STENCIL_REF \|
	CSO_BIT_DEPTH_STENCIL_ALPHA \|
	CSO_BIT_RASTERIZER \|
	CSO_BIT_SAMPLE_MASK \|
	CSO_BIT_MIN_SAMPLES \|
	CSO_BIT_VIEWPORT \|
	CSO_BIT_STREAM_OUTPUTS \|
	CSO_BIT_VERTEX_ELEMENTS \|
	CSO_BIT_AUX_VERTEX_BUFFER_SLOT \|
	CSO_BIT_PAUSE_QUERIES \|
	CSO_BITS_ALL_SHADERS));

	/* blend state: RGBA masking */
	{
	struct pipe_blend_state blend;
	memset(&blend, 0, sizeof(blend));
	if (clear_buffers & PIPE_CLEAR_COLOR) {
	int num_buffers = ctx->Extensions.EXT_draw_buffers2 ?
	ctx->DrawBuffer->_NumColorDrawBuffers : 1;
	int i;

	blend.independent_blend_enable = num_buffers > 1;

	for (i = 0; i < num_buffers; i++) {
	if (!(clear_buffers & (PIPE_CLEAR_COLOR0 << i)))
	continue;

	if (ctx->Color.ColorMask[i][0])
	blend.rt[i].colormask \|= PIPE_MASK_R;
	if (ctx->Color.ColorMask[i][1])
	blend.rt[i].colormask \|= PIPE_MASK_G;
	if (ctx->Color.ColorMask[i][2])
	blend.rt[i].colormask \|= PIPE_MASK_B;
	if (ctx->Color.ColorMask[i][3])
	blend.rt[i].colormask \|= PIPE_MASK_A;
	}

	if (ctx->Color.DitherFlag)
	blend.dither = 1;
	}
	cso_set_blend(cso, &blend);
	}

	/* depth_stencil state: always pass/set to ref value */
	{
	struct pipe_depth_stencil_alpha_state depth_stencil;
	memset(&depth_stencil, 0, sizeof(depth_stencil));
	if (clear_buffers & PIPE_CLEAR_DEPTH) {
	depth_stencil.depth.enabled = 1;
	depth_stencil.depth.writemask = 1;
	depth_stencil.depth.func = PIPE_FUNC_ALWAYS;
	}

	if (clear_buffers & PIPE_CLEAR_STENCIL) {
	struct pipe_stencil_ref stencil_ref;
	memset(&stencil_ref, 0, sizeof(stencil_ref));
	depth_stencil.stencil[0].enabled = 1;
	depth_stencil.stencil[0].func = PIPE_FUNC_ALWAYS;
	depth_stencil.stencil[0].fail_op = PIPE_STENCIL_OP_REPLACE;
	depth_stencil.stencil[0].zpass_op = PIPE_STENCIL_OP_REPLACE;
	depth_stencil.stencil[0].zfail_op = PIPE_STENCIL_OP_REPLACE;
	depth_stencil.stencil[0].valuemask = 0xff;
	depth_stencil.stencil[0].writemask = ctx->Stencil.WriteMask[0] & 0xff;
	stencil_ref.ref_value[0] = ctx->Stencil.Clear;
	cso_set_stencil_ref(cso, &stencil_ref);
	}

	cso_set_depth_stencil_alpha(cso, &depth_stencil);
	}

	cso_set_vertex_elements(cso, 2, st->util_velems);
	cso_set_stream_outputs(cso, 0, NULL, NULL);
	cso_set_sample_mask(cso, ~0);
	cso_set_min_samples(cso, 1);
	cso_set_rasterizer(cso, &st->clear.raster);

	/* viewport state: viewport matching window dims */
	cso_set_viewport_dims(st->cso_context, fb_width, fb_height,
	st_fb_orientation(fb) == Y_0_TOP);

	set_fragment_shader(st);
	cso_set_tessctrl_shader_handle(cso, NULL);
	cso_set_tesseval_shader_handle(cso, NULL);

	if (num_layers > 1)
	set_vertex_shader_layered(st);
	else
	set_vertex_shader(st);

	/* draw quad matching scissor rect.
	*
	* Note: if we're only clearing depth/stencil we still setup vertices
	* with color, but they'll be ignored.
	*
	* We can't translate the clear color to the colorbuffer format,
	* because different colorbuffers may have different formats.
	*/
	if (!st_draw_quad(st, x0, y0, x1, y1,
	ctx->Depth.Clear * 2.0f - 1.0f,
	0.0f, 0.0f, 0.0f, 0.0f,
	(const float *) &ctx->Color.ClearColor.f,
	num_layers)) {
	_mesa_error(ctx, GL_OUT_OF_MEMORY, "glClear");
	}

	/* Restore pipe state */
	cso_restore_state(cso);
	}


	/**
	* Return if the scissor must be enabled during the clear.
	*/
	static inline GLboolean
	is_scissor_enabled(struct gl_context ctx, struct gl_renderbuffer rb)
	{
	const struct gl_scissor_rect *scissor = &ctx->Scissor.ScissorArray[0];

	return (ctx->Scissor.EnableFlags & 1) &&
	(scissor->X > 0 \|\|
	scissor->Y > 0 \|\|
	scissor->X + scissor->Width < (int)rb->Width \|\|
	scissor->Y + scissor->Height < (int)rb->Height);
	}

	/**
	* Return if window rectangles must be enabled during the clear.
	*/
	static inline bool
	is_window_rectangle_enabled(struct gl_context *ctx)
	{
	if (ctx->DrawBuffer == ctx->WinSysDrawBuffer)
	return false;
	return ctx->Scissor.NumWindowRects > 0 \|\|
	ctx->Scissor.WindowRectMode == GL_INCLUSIVE_EXT;
	}


	/**
	* Return if all of the color channels are masked.
	*/
	static inline GLboolean
	is_color_disabled(struct gl_context *ctx, int i)
	{
	return !ctx->Color.ColorMask[i][0] &&
	!ctx->Color.ColorMask[i][1] &&
	!ctx->Color.ColorMask[i][2] &&
	!ctx->Color.ColorMask[i][3];
	}


	/**
	* Return if any of the color channels are masked.
	*/
	static inline GLboolean
	is_color_masked(struct gl_context *ctx, int i)
	{
	return !ctx->Color.ColorMask[i][0] \|\|
	!ctx->Color.ColorMask[i][1] \|\|
	!ctx->Color.ColorMask[i][2] \|\|
	!ctx->Color.ColorMask[i][3];
	}


	/**
	* Return if all of the stencil bits are masked.
	*/
	static inline GLboolean
	is_stencil_disabled(struct gl_context ctx, struct gl_renderbuffer rb)
	{
	const GLuint stencilMax = 0xff;

	assert(_mesa_get_format_bits(rb->Format, GL_STENCIL_BITS) > 0);
	return (ctx->Stencil.WriteMask[0] & stencilMax) == 0;
	}


	/**
	* Return if any of the stencil bits are masked.
	*/
	static inline GLboolean
	is_stencil_masked(struct gl_context ctx, struct gl_renderbuffer rb)
	{
	const GLuint stencilMax = 0xff;

	assert(_mesa_get_format_bits(rb->Format, GL_STENCIL_BITS) > 0);
	return (ctx->Stencil.WriteMask[0] & stencilMax) != stencilMax;
	}


	/**
	* Called via ctx->Driver.Clear()
	*/
	static void
	st_Clear(struct gl_context *ctx, GLbitfield mask)
	{
	struct st_context *st = st_context(ctx);
	struct gl_renderbuffer *depthRb
	= ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer;
	struct gl_renderbuffer *stencilRb
	= ctx->DrawBuffer->Attachment[BUFFER_STENCIL].Renderbuffer;
	GLbitfield quad_buffers = 0x0;
	GLbitfield clear_buffers = 0x0;
	GLuint i;

	st_flush_bitmap_cache(st);
	st_invalidate_readpix_cache(st);

	/* This makes sure the pipe has the latest scissor, etc values */
	st_validate_state(st, ST_PIPELINE_CLEAR);

	if (mask & BUFFER_BITS_COLOR) {
	for (i = 0; i < ctx->DrawBuffer->_NumColorDrawBuffers; i++) {
	GLint b = ctx->DrawBuffer->_ColorDrawBufferIndexes[i];

	if (b >= 0 && mask & (1 << b)) {
	struct gl_renderbuffer *rb
	= ctx->DrawBuffer->Attachment[b].Renderbuffer;
	struct st_renderbuffer *strb = st_renderbuffer(rb);
	int colormask_index = ctx->Extensions.EXT_draw_buffers2 ? i : 0;

	if (!strb \|\| !strb->surface)
	continue;

	if (is_color_disabled(ctx, colormask_index))
	continue;

	if (is_scissor_enabled(ctx, rb) \|\|
	is_window_rectangle_enabled(ctx) \|\|
	is_color_masked(ctx, colormask_index))
	quad_buffers \|= PIPE_CLEAR_COLOR0 << i;
	else
	clear_buffers \|= PIPE_CLEAR_COLOR0 << i;
	}
	}
	}

	if (mask & BUFFER_BIT_DEPTH) {
	struct st_renderbuffer *strb = st_renderbuffer(depthRb);

	if (strb->surface && ctx->Depth.Mask) {
	if (is_scissor_enabled(ctx, depthRb) \|\|
	is_window_rectangle_enabled(ctx))
	quad_buffers \|= PIPE_CLEAR_DEPTH;
	else
	clear_buffers \|= PIPE_CLEAR_DEPTH;
	}
	}
	if (mask & BUFFER_BIT_STENCIL) {
	struct st_renderbuffer *strb = st_renderbuffer(stencilRb);

	if (strb->surface && !is_stencil_disabled(ctx, stencilRb)) {
	if (is_scissor_enabled(ctx, stencilRb) \|\|
	is_window_rectangle_enabled(ctx) \|\|
	is_stencil_masked(ctx, stencilRb))
	quad_buffers \|= PIPE_CLEAR_STENCIL;
	else
	clear_buffers \|= PIPE_CLEAR_STENCIL;
	}
	}

	/* Always clear depth and stencil together.
	* This can only happen when the stencil writemask is not a full mask.
	*/
	if (quad_buffers & PIPE_CLEAR_DEPTHSTENCIL &&
	clear_buffers & PIPE_CLEAR_DEPTHSTENCIL) {
	quad_buffers \|= clear_buffers & PIPE_CLEAR_DEPTHSTENCIL;
	clear_buffers &= ~PIPE_CLEAR_DEPTHSTENCIL;
	}

	/* Only use quad-based clearing for the renderbuffers which cannot
	* use pipe->clear. We want to always use pipe->clear for the other
	* renderbuffers, because it's likely to be faster.
	*/
	if (quad_buffers) {
	clear_with_quad(ctx, quad_buffers);
	}
	if (clear_buffers) {
	/* We can't translate the clear color to the colorbuffer format,
	* because different colorbuffers may have different formats.
	*/
	st->pipe->clear(st->pipe, clear_buffers,
	(union pipe_color_union*)&ctx->Color.ClearColor,
	ctx->Depth.Clear, ctx->Stencil.Clear);
	}
	if (mask & BUFFER_BIT_ACCUM)
	_mesa_clear_accum_buffer(ctx);
	}


	void
	st_init_clear_functions(struct dd_function_table *functions)
	{
	functions->Clear = st_Clear;
	}