Skip to content

Commit

Permalink
Fixed vertex attribute aliasing in OpenGL glue code.
Browse files Browse the repository at this point in the history 
Another look at the GL_ARB_vertex_shader spec suggests we don't need a
 separate path for POSITION0...the GL reserves attr #0 to be equivalent to
 glVertexPointer(), but without the limitations.

--HG--
branch : trunk
  • Loading branch information
@icculus
icculus committed Apr 28, 2008
1 parent 758fe93 commit 109cccb
Showing 1 changed file with 29 additions and 66 deletions.
95 changes: 29 additions & 66 deletions mojoshader_opengl.c
View file
Expand Up @@ -51,11 +51,8 @@ struct MOJOSHADER_glProgram
uint32 refcount;
};

// A few entry points in base OpenGL that lack function pointer prototypes...
// Entry points in base OpenGL that lack function pointer prototypes...
typedef WINGDIAPI const GLubyte * (APIENTRYP PFNGLGETSTRINGPROC) (GLenum name);
typedef WINGDIAPI void (APIENTRYP PFNGLDISABLECLIENTSTATEPROC) (GLenum array);
typedef WINGDIAPI void (APIENTRYP PFNGLENABLECLIENTSTATEPROC) (GLenum array);
typedef WINGDIAPI void (APIENTRYP PFNGLVERTEXPOINTERPROC) (GLint size, GLenum type, GLsizei stride, const GLvoid *pointer);

struct MOJOSHADER_glContext
{
Expand Down Expand Up @@ -94,9 +91,7 @@ struct MOJOSHADER_glContext
PFNGLCOMPILESHADERARBPROC glCompileShader;
PFNGLCREATEPROGRAMOBJECTARBPROC glCreateProgramObject;
PFNGLCREATESHADEROBJECTARBPROC glCreateShaderObject;
PFNGLDISABLECLIENTSTATEPROC glDisableClientState;
PFNGLDISABLEVERTEXATTRIBARRAYARBPROC glDisableVertexAttribArray;
PFNGLENABLECLIENTSTATEPROC glEnableClientState;
PFNGLENABLEVERTEXATTRIBARRAYARBPROC glEnableVertexAttribArray;
PFNGLGETATTRIBLOCATIONARBPROC glGetAttribLocation;
PFNGLGETINFOLOGARBPROC glGetInfoLog;
Expand All @@ -109,7 +104,6 @@ struct MOJOSHADER_glContext
PFNGLUNIFORM4IVARBPROC glUniform4iv;
PFNGLUSEPROGRAMOBJECTARBPROC glUseProgramObject;
PFNGLVERTEXATTRIBPOINTERARBPROC glVertexAttribPointer;
PFNGLVERTEXPOINTERPROC glVertexPointer;
};

static MOJOSHADER_glContext *ctx = NULL;
Expand Down Expand Up @@ -179,9 +173,6 @@ static void lookup_entry_points(void *(*lookup)(const char *fnname))
{
#define DO_LOOKUP(ext, typ, fn) ctx->fn = (typ) loadsym(lookup, #fn, &ctx->have_##ext)
DO_LOOKUP(base_opengl, PFNGLGETSTRINGPROC, glGetString);
DO_LOOKUP(base_opengl, PFNGLDISABLECLIENTSTATEPROC, glDisableClientState);
DO_LOOKUP(base_opengl, PFNGLENABLECLIENTSTATEPROC, glEnableClientState);
DO_LOOKUP(base_opengl, PFNGLVERTEXPOINTERPROC, glVertexPointer);
DO_LOOKUP(GL_ARB_shader_objects, PFNGLDELETEOBJECTARBPROC, glDeleteObject);
DO_LOOKUP(GL_ARB_shader_objects, PFNGLATTACHOBJECTARBPROC, glAttachObject);
DO_LOOKUP(GL_ARB_shader_objects, PFNGLCOMPILESHADERARBPROC, glCompileShader);
Expand Down Expand Up @@ -564,9 +555,10 @@ void MOJOSHADER_glBindProgram(MOJOSHADER_glProgram *program)
return; // nothing to do.

// Disable any client-side arrays the current program could have used.
// !!! FIXME: don't disable yet...see which ones get reused, and disable
// !!! FIXME: only what we don't need in MOJOSHADER_glProgramReady().
if (ctx->bound_program != NULL)
{
ctx->glDisableClientState(GL_VERTEX_ARRAY);
const int count = ctx->bound_program->attribute_count;
for (i = 0; i < count; i++)
{
Expand Down Expand Up @@ -669,30 +661,6 @@ void MOJOSHADER_glSetPixelShaderUniformB(unsigned int idx, const int *data,
} // MOJOSHADER_glSetPixelShaderUniformB


static inline GLenum opengl_posattr_type(const MOJOSHADER_attributeType type)
{
// we don't ever use the glVertexPointer() stream, so we just need to
// make the data types reasonably match, so the GL doesn't overrun
// the buffer when dereferencing it.

switch (type)
{
case MOJOSHADER_ATTRIBUTE_UNKNOWN: return GL_NONE; // oh well.
case MOJOSHADER_ATTRIBUTE_BYTE: return GL_NONE; // oh well.
case MOJOSHADER_ATTRIBUTE_UBYTE: return GL_NONE; // oh well.
case MOJOSHADER_ATTRIBUTE_SHORT: return GL_SHORT;
case MOJOSHADER_ATTRIBUTE_USHORT: return GL_SHORT;
case MOJOSHADER_ATTRIBUTE_INT: return GL_INT;
case MOJOSHADER_ATTRIBUTE_UINT: return GL_INT;
case MOJOSHADER_ATTRIBUTE_FLOAT: return GL_FLOAT;
case MOJOSHADER_ATTRIBUTE_DOUBLE: return GL_DOUBLE;
case MOJOSHADER_ATTRIBUTE_HALF_FLOAT: return GL_SHORT;
} // switch

return GL_NONE; // oh well. Raises a GL error later.
} // opengl_posattr_type


static inline GLenum opengl_attr_type(const MOJOSHADER_attributeType type)
{
switch (type)
Expand Down Expand Up @@ -726,44 +694,39 @@ void MOJOSHADER_glSetVertexAttribute(MOJOSHADER_usage usage,
if ((ctx->bound_program == NULL) || (ctx->bound_program->vertex == NULL))
return;

// Since glVertexPointer() lacks the flexibility that we can get from
// glVertexAttribPointer(), we set POSITION0 to a generic vertex
// attribute, and the shaders we generate know to look there instead of
// GLSL's gl_Position global variable. But to keep the GL handy, we
// also set the best possible equivalent with glVertexPointer(). Messy.
const GLenum gl_type = opengl_attr_type(type);
const GLboolean norm = (normalized) ? GL_TRUE : GL_FALSE;
GLuint gl_index = 0;

if ((usage == MOJOSHADER_USAGE_POSITION) && (index == 0))
{
// !!! FIXME: fails if size==1.
ctx->glVertexPointer(size, opengl_posattr_type(type), stride, ptr);
ctx->glEnableClientState(GL_VERTEX_ARRAY);
} // if
// We have to map POSITION0 to generic vertex attribute 0; the
// GL_ARB_vertex_shader spec says this is equivalent to using
// glVertexPointer(), but without the limitations of that entry point.

int i;
GLuint gl_index = 0;
const int count = ctx->bound_program->attribute_count;
for (i = 0; i < count; i++)
if ((usage != MOJOSHADER_USAGE_POSITION) || (index != 0))
{
const AttributeMap *map = &ctx->bound_program->attributes[i];
const MOJOSHADER_attribute *a = map->attribute;
int i;
const int count = ctx->bound_program->attribute_count;
for (i = 0; i < count; i++)
{
const AttributeMap *map = &ctx->bound_program->attributes[i];
const MOJOSHADER_attribute *a = map->attribute;

// !!! FIXME: is this array guaranteed to be sorted by usage?
// !!! FIXME: if so, we can break out of the loop if a->usage > usage.
// !!! FIXME: is this array guaranteed to be sorted by usage?
// !!! FIXME: if so, we can break if a->usage > usage.

if ((a->usage == usage) && (a->index == index))
{
gl_index = map->location;
break;
} // if
} // for
if ((a->usage == usage) && (a->index == index))
{
gl_index = map->location;
break;
} // if
} // for

if (gl_index != 0)
{
const GLenum gl_type = opengl_attr_type(type);
const GLboolean norm = (normalized) ? GL_TRUE : GL_FALSE;
ctx->glVertexAttribPointer(gl_index, size, gl_type, norm, stride, ptr);
ctx->glEnableVertexAttribArray(gl_index);
if (gl_index == 0)
return; // nothing to do, this shader doesn't use this stream.
} // if

ctx->glVertexAttribPointer(gl_index, size, gl_type, norm, stride, ptr);
ctx->glEnableVertexAttribArray(gl_index);
} // MOJOSHADER_glSetVertexAttribute


Expand Down

0 comments on commit 109cccb

Please sign in to comment.