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[cogl-vertex-buffer] fix n_components validation for GL's builtin attributes

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glVertexPointer expects positions with 2, 3 or 4 components, glColorPointer
expects colors with 3 or 4 components and glNormalPointer expects normals
with three components so when adding vertex buffer atributes with the names
"gl_Vertex", "gl_Color" or "gl_Normal" we assert these constraints and print
an explanation to the developer if not met.

This also fixes the previosly incorrect constraint that gl_Normal attributes
must have n_components == 1; thanks to Cat Sidhe for reporting this:

Bug: http://bugzilla.openedhand.com/show_bug.cgi?id=1819
This commit is contained in:
Robert Bragg 2009-09-24 17:34:26 +01:00
parent 84441610de
commit 61e6c57bdd
1 changed files with 15 additions and 4 deletions
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17
common/cogl-vertex-buffer.c
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@ -241,7 +241,7 @@ cogl_vertex_buffer_get_n_vertices (CoglHandle handle)
*/ */
static CoglVertexBufferAttribFlags static CoglVertexBufferAttribFlags
validate_gl_attribute (const char *gl_attribute, validate_gl_attribute (const char *gl_attribute,
guint8 *n_components, guint8 n_components,
guint8 *texture_unit) guint8 *texture_unit)
{ {
CoglVertexBufferAttribFlags type; CoglVertexBufferAttribFlags type;
@ -256,10 +256,18 @@ validate_gl_attribute (const char *gl_attribute,
if (strncmp (gl_attribute, "Vertex", name_len) == 0) if (strncmp (gl_attribute, "Vertex", name_len) == 0)
{ {
if (G_UNLIKELY (n_components == 1))
g_critical ("glVertexPointer doesn't allow 1 component vertex "
"positions so we currently only support \"gl_Vertex\" "
"attributes where n_components == 2, 3 or 4");
type = COGL_VERTEX_BUFFER_ATTRIB_FLAG_VERTEX_ARRAY; type = COGL_VERTEX_BUFFER_ATTRIB_FLAG_VERTEX_ARRAY;
} }
else if (strncmp (gl_attribute, "Color", name_len) == 0) else if (strncmp (gl_attribute, "Color", name_len) == 0)
{ {
if (G_UNLIKELY (n_components != 3 && n_components != 4))
g_critical ("glColorPointer expects 3 or 4 component colors so we "
"currently only support \"gl_Color\" attributes where "
"n_components == 3 or 4");
type = COGL_VERTEX_BUFFER_ATTRIB_FLAG_COLOR_ARRAY; type = COGL_VERTEX_BUFFER_ATTRIB_FLAG_COLOR_ARRAY;
} }
else if (strncmp (gl_attribute, else if (strncmp (gl_attribute,
@ -280,7 +288,10 @@ validate_gl_attribute (const char *gl_attribute,
} }
else if (strncmp (gl_attribute, "Normal", name_len) == 0) else if (strncmp (gl_attribute, "Normal", name_len) == 0)
{ {
*n_components = 1; if (G_UNLIKELY (n_components != 3))
g_critical ("glNormalPointer expects 3 component normals so we "
"currently only support \"gl_Normal\" attributes where "
"n_components == 3");
type = COGL_VERTEX_BUFFER_ATTRIB_FLAG_NORMAL_ARRAY; type = COGL_VERTEX_BUFFER_ATTRIB_FLAG_NORMAL_ARRAY;
} }
else else
@ -468,7 +479,7 @@ cogl_vertex_buffer_add (CoglHandle handle,
if (strncmp (attribute_name, "gl_", 3) == 0) if (strncmp (attribute_name, "gl_", 3) == 0)
{ {
flags |= validate_gl_attribute (attribute_name + 3, flags |= validate_gl_attribute (attribute_name + 3,
&n_components, n_components,
&texture_unit); &texture_unit);
if (flags & COGL_VERTEX_BUFFER_ATTRIB_FLAG_INVALID) if (flags & COGL_VERTEX_BUFFER_ATTRIB_FLAG_INVALID)
return; return;