[Mesa-dev] [PATCH v2] mesa: handle a bunch of formats in IMPLEMENTATION_COLOR_READ_*

[Tomeu Vizoso]

Virgl could save a lot of work converting buffers in the host side
between formats if Mesa supported a bunch of other formats when reading
pixels.

This commit adds cases to handle specific formats so that the values
reported by the two calls match more closely the underlying native
formats.

In GLES is important that IMPLEMENTATION_COLOR_READ_* return the native
format and data type because the spec only allows reading with those,
besides GL_RGBA or GL_RGBA_INTEGER.

Additionally, because virgl currently doesn't implement such
conversions, this commit fixes several tests in
dEQP-GLES3.functional.fbo.color.clear.*, when using virgl in the guest
side.

Additionally, assert that those functions' result match
_mesa_format_matches_format_and_type, so both functions are kept in
sync.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso at collabora.com>

v2: * Let R10G10B10A2_UINT fall back to GL_RGBA_INTEGER (Eric Anholt)
    * Assert with _mesa_format_matches_format_and_type (Eric Anholt)
---
 src/mesa/main/framebuffer.c | 117 ++++++++++++++++++++++++------------
 1 file changed, 80 insertions(+), 37 deletions(-)

diff --git a/src/mesa/main/framebuffer.c b/src/mesa/main/framebuffer.c
index 8e751b453b75..6be4ecbc58f9 100644
--- a/src/mesa/main/framebuffer.c
+++ b/src/mesa/main/framebuffer.c
@@ -834,22 +834,72 @@ _mesa_get_color_read_format(struct gl_context *ctx,
    }
    else {
       const mesa_format format = fb->_ColorReadBuffer->Format;
-      const GLenum data_type = _mesa_get_format_datatype(format);
-
-      if (format == MESA_FORMAT_B8G8R8A8_UNORM)
-         return GL_BGRA;
-      else if (format == MESA_FORMAT_B5G6R5_UNORM)
-         return GL_RGB;
-      else if (format == MESA_FORMAT_R_UNORM8)
-         return GL_RED;
-
-      switch (data_type) {
-      case GL_UNSIGNED_INT:
-      case GL_INT:
-         return GL_RGBA_INTEGER;
+      GLenum gl_format, data_type;
+      GLuint comps;
+
+      _mesa_uncompressed_format_to_type_and_comps(format, &data_type, &comps);
+
+      switch(format) {
+      case MESA_FORMAT_RGBA_UINT8:
+         gl_format = GL_RGBA_INTEGER;
+         break;
+      case MESA_FORMAT_B8G8R8A8_UNORM:
+         gl_format = GL_BGRA;
+         break;
+      case MESA_FORMAT_B5G6R5_UNORM:
+      case MESA_FORMAT_R11G11B10_FLOAT:
+         gl_format = GL_RGB;
+         break;
+      case MESA_FORMAT_RG_FLOAT32:
+      case MESA_FORMAT_RG_FLOAT16:
+      case MESA_FORMAT_R8G8_UNORM:
+         gl_format = GL_RG;
+         break;
+      case MESA_FORMAT_RG_SINT32:
+      case MESA_FORMAT_RG_UINT32:
+      case MESA_FORMAT_RG_SINT16:
+      case MESA_FORMAT_RG_UINT16:
+      case MESA_FORMAT_RG_SINT8:
+      case MESA_FORMAT_RG_UINT8:
+         gl_format = GL_RG_INTEGER;
+         break;
+      case MESA_FORMAT_R_FLOAT32:
+      case MESA_FORMAT_R_FLOAT16:
+      case MESA_FORMAT_R_UNORM8:
+         gl_format = GL_RED;
+         break;
+      case MESA_FORMAT_R_SINT32:
+      case MESA_FORMAT_R_UINT32:
+      case MESA_FORMAT_R_SINT16:
+      case MESA_FORMAT_R_UINT16:
+      case MESA_FORMAT_R_SINT8:
+      case MESA_FORMAT_R_UINT8:
+         gl_format = GL_RED_INTEGER;
+         break;
       default:
-         return GL_RGBA;
+         switch (data_type) {
+         case GL_UNSIGNED_INT:
+         case GL_UNSIGNED_INT_2_10_10_10_REV:
+         case GL_UNSIGNED_SHORT:
+         case GL_INT:
+         case GL_SHORT:
+         case GL_BYTE:
+            gl_format = GL_RGBA_INTEGER;
+            break;
+         default:
+            gl_format = GL_RGBA;
+            break;
+         }
       }
+
+      /* GL_RGBA and GL_RGBA_INTEGER should be always valid */
+      assert(gl_format == GL_RGBA ||
+             gl_format == GL_RGBA_INTEGER ||
+             _mesa_format_matches_format_and_type(format, gl_format,
+                                                  data_type,
+                                                  ctx->Pack.SwapBytes, NULL));
+
+      return gl_format;
    }
 }
 
@@ -882,29 +932,22 @@ _mesa_get_color_read_type(struct gl_context *ctx,
       return GL_NONE;
    }
    else {
-      const GLenum format = fb->_ColorReadBuffer->Format;
-      const GLenum data_type = _mesa_get_format_datatype(format);
-
-      if (format == MESA_FORMAT_B5G6R5_UNORM)
-         return GL_UNSIGNED_SHORT_5_6_5;
-
-      if (format == MESA_FORMAT_B10G10R10A2_UNORM ||
-          format == MESA_FORMAT_B10G10R10X2_UNORM ||
-          format == MESA_FORMAT_R10G10B10A2_UNORM ||
-          format == MESA_FORMAT_R10G10B10X2_UNORM)
-         return GL_UNSIGNED_INT_2_10_10_10_REV;
-
-      switch (data_type) {
-      case GL_SIGNED_NORMALIZED:
-         return GL_BYTE;
-      case GL_UNSIGNED_INT:
-      case GL_INT:
-      case GL_FLOAT:
-         return data_type;
-      case GL_UNSIGNED_NORMALIZED:
-      default:
-         return GL_UNSIGNED_BYTE;
-      }
+      const mesa_format format = fb->_ColorReadBuffer->Format;
+      GLenum gl_format, data_type;
+      GLuint comps;
+
+      _mesa_uncompressed_format_to_type_and_comps(format, &data_type, &comps);
+
+      gl_format = _mesa_get_color_read_format(ctx, fb, NULL);
+
+      /* GL_RGBA and GL_RGBA_INTEGER should be always valid */
+      assert(gl_format == GL_RGBA ||
+             gl_format == GL_RGBA_INTEGER ||
+             _mesa_format_matches_format_and_type(format, gl_format,
+                                                  data_type,
+                                                  ctx->Pack.SwapBytes, NULL));
+
+      return data_type;
    }
 }
 
-- 
2.17.0