[Mesa-dev] [PATCH v2 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. The extension is not yet enabled by
default because it doesn't work with multisample textures as they don't have a
simple linear layout.

Reviewed-by: Jason Ekstrand <jason.ekstrand at intel.com>
---
 src/mesa/main/texstore.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/mesa/main/texstore.h |  7 +++++
 2 files changed, 79 insertions(+)

diff --git a/src/mesa/main/texstore.c b/src/mesa/main/texstore.c
index d363f9f..555ac03 100644
--- a/src/mesa/main/texstore.c
+++ b/src/mesa/main/texstore.c
@@ -4079,6 +4079,78 @@ _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)
+{
+   GLsizei y;
+
+   for (y = 0; y < height; y++) {
+      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 y, x;
+
+   for (y = 0; y < height; y++) {
+      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