[Mesa-dev] [PATCH 4/5] texstore: Add a generic implementation of GL_ARB_clear_texture

[Neil Roberts]

Adds an implmentation of the ClearTexSubImage driver entry point that just
maps the texture and writes the values in. This should work as a reliable
fallback on any driver.
---
 src/mesa/drivers/common/driverfuncs.c |  2 +
 src/mesa/main/texstore.c              | 70 +++++++++++++++++++++++++++++++++++
 src/mesa/main/texstore.h              |  7 ++++
 3 files changed, 79 insertions(+)

diff --git a/src/mesa/drivers/common/driverfuncs.c b/src/mesa/drivers/common/driverfuncs.c
index ee8b390..34b6fef 100644
--- a/src/mesa/drivers/common/driverfuncs.c
+++ b/src/mesa/drivers/common/driverfuncs.c
@@ -95,6 +95,7 @@ _mesa_init_driver_functions(struct dd_function_table *driver)
    driver->TexImage = _mesa_store_teximage;
    driver->TexSubImage = _mesa_store_texsubimage;
    driver->GetTexImage = _mesa_meta_GetTexImage;
+   driver->ClearTexSubImage = _mesa_store_cleartexsubimage;
    driver->CopyTexSubImage = _mesa_meta_CopyTexSubImage;
    driver->GenerateMipmap = _mesa_meta_GenerateMipmap;
    driver->TestProxyTexImage = _mesa_test_proxy_teximage;
@@ -333,4 +334,5 @@ _mesa_init_driver_state(struct gl_context *ctx)
 void
 _mesa_init_driver_extensions(struct gl_context *ctx)
 {
+   ctx->Extensions.ARB_clear_texture = GL_TRUE;
 }
diff --git a/src/mesa/main/texstore.c b/src/mesa/main/texstore.c
index cb81f3f..9c90492 100644
--- a/src/mesa/main/texstore.c
+++ b/src/mesa/main/texstore.c
@@ -4157,6 +4157,76 @@ _mesa_store_texsubimage(struct gl_context *ctx, GLuint dims,
                      format, type, pixels, packing, "glTexSubImage");
 }
 
+static void
+clear_image_to_zero(GLubyte *dstMap, GLint dstRowStride,
+                    GLsizei width, GLsizei height,
+                    GLsizei clearValueSize)
+{
+   while (height-- > 0) {
+      memset(dstMap, 0, clearValueSize * width);
+      dstMap += dstRowStride;
+   }
+}
+
+static void
+clear_image_to_value(GLubyte *dstMap, GLint dstRowStride,
+                     GLsizei width, GLsizei height,
+                     const GLvoid *clearValue,
+                     GLsizei clearValueSize)
+{
+   GLsizei x;
+
+   while (height-- > 0) {
+      for (x = 0; x < width; x++) {
+         memcpy(dstMap, clearValue, clearValueSize);
+         dstMap += clearValueSize;
+      }
+      dstMap += dstRowStride - clearValueSize * width;
+   }
+}
+
+/*
+ * Fallback for Driver.ClearTexSubImage().
+ */
+void
+_mesa_store_cleartexsubimage(struct gl_context *ctx,
+                             struct gl_texture_image *texImage,
+                             GLint xoffset, GLint yoffset, GLint zoffset,
+                             GLsizei width, GLsizei height, GLsizei depth,
+                             const GLvoid *clearValue)
+{
+   GLubyte *dstMap;
+   GLint dstRowStride;
+   GLsizeiptr clearValueSize;
+   GLsizei z;
+
+   clearValueSize = _mesa_get_format_bytes(texImage->TexFormat);
+
+   for (z = 0; z < depth; z++) {
+      ctx->Driver.MapTextureImage(ctx, texImage,
+                                  z + zoffset, xoffset, yoffset,
+                                  width, height,
+                                  GL_MAP_WRITE_BIT,
+                                  &dstMap, &dstRowStride);
+      if (dstMap == NULL) {
+         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glClearTex*Image");
+         return;
+      }
+
+      if (clearValue) {
+         clear_image_to_value(dstMap, dstRowStride,
+                              width, height,
+                              clearValue,
+                              clearValueSize);
+      } else {
+         clear_image_to_zero(dstMap, dstRowStride,
+                             width, height,
+                             clearValueSize);
+      }
+
+      ctx->Driver.UnmapTextureImage(ctx, texImage, z + zoffset);
+   }
+}
 
 /**
  * Fallback for Driver.CompressedTexImage()
diff --git a/src/mesa/main/texstore.h b/src/mesa/main/texstore.h
index c4cfffd..dd1e1d0 100644
--- a/src/mesa/main/texstore.h
+++ b/src/mesa/main/texstore.h
@@ -118,6 +118,13 @@ _mesa_store_texsubimage(struct gl_context *ctx, GLuint dims,
 
 
 extern void
+_mesa_store_cleartexsubimage(struct gl_context *ctx,
+                             struct gl_texture_image *texImage,
+                             GLint xoffset, GLint yoffset, GLint zoffset,
+                             GLsizei width, GLsizei height, GLsizei depth,
+                             const GLvoid *clearValue);
+
+extern void
 _mesa_store_compressed_teximage(struct gl_context *ctx, GLuint dims,
                                 struct gl_texture_image *texImage,
                                 GLsizei imageSize, const GLvoid *data);
-- 
1.9.3