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// Gawain shader interface (C --> GLSL)
//
// This code is part of the Gawain library, with modifications
// specific to integration with Blender.
//
// Copyright 2017 Mike Erwin
//
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of
// the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.
#include "shader_interface.h"
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#define SUPPORT_LEGACY_GLSL 1
#define DEBUG_SHADER_INTERFACE 0
#if DEBUG_SHADER_INTERFACE
#include <stdio.h>
#endif
static const char* BuiltinUniform_name(BuiltinUniform u)
{
static const char* names[] =
{
[UNIFORM_NONE] = NULL,
[UNIFORM_MODELVIEW] = "ModelViewMatrix",
[UNIFORM_PROJECTION] = "ProjectionMatrix",
[UNIFORM_MVP] = "ModelViewProjectionMatrix",
[UNIFORM_MODELVIEW_INV] = "ModelViewInverseMatrix",
[UNIFORM_PROJECTION_INV] = "ProjectionInverseMatrix",
[UNIFORM_NORMAL] = "NormalMatrix",
[UNIFORM_COLOR] = "color",
[UNIFORM_CUSTOM] = NULL
};
return names[u];
}
static bool match(const char* a, const char* b)
{
return strcmp(a, b) == 0;
}
static unsigned hash_string(const char *str)
{
unsigned i = 0, c;
while ((c = *str++))
{
i = i * 37 + c;
}
return i;
}
static void set_input_name(ShaderInput* input, const char* name)
{
input->name = name;
input->name_hash = hash_string(name);
}
// keep these in sync with BuiltinUniform order
#define FIRST_MAT4_UNIFORM UNIFORM_MODELVIEW
#define LAST_MAT4_UNIFORM UNIFORM_PROJECTION_INV
static bool setup_builtin_uniform(ShaderInput* input, const char* name)
{
// TODO: reject DOUBLE, IMAGE, ATOMIC_COUNTER gl_types
// detect built-in uniforms (gl_type and name must match)
// if a match is found, use BuiltinUniform_name so name buffer space can be reclaimed
switch (input->gl_type)
{
case GL_FLOAT_MAT4:
for (BuiltinUniform u = FIRST_MAT4_UNIFORM; u <= LAST_MAT4_UNIFORM; ++u)
{
const char* builtin_name = BuiltinUniform_name(u);
if (match(name, builtin_name))
{
set_input_name(input, builtin_name);
input->builtin_type = u;
return true;
}
}
break;
case GL_FLOAT_MAT3:
{
const char* builtin_name = BuiltinUniform_name(UNIFORM_NORMAL);
if (match(name, builtin_name))
{
set_input_name(input, builtin_name);
input->builtin_type = UNIFORM_NORMAL;
return true;
}
}
break;
case GL_FLOAT_VEC4:
{
const char* builtin_name = BuiltinUniform_name(UNIFORM_COLOR);
if (match(name, builtin_name))
{
set_input_name(input, builtin_name);
input->builtin_type = UNIFORM_COLOR;
return true;
}
}
break;
default:
;
}
input->builtin_type = UNIFORM_CUSTOM;
return false;
}
ShaderInterface* ShaderInterface_create(GLint program)
{
#if DEBUG_SHADER_INTERFACE
printf("%s {\n", __func__); // enter function
#endif
GLint uniform_ct, attrib_ct;
glGetProgramiv(program, GL_ACTIVE_UNIFORMS, &uniform_ct);
glGetProgramiv(program, GL_ACTIVE_ATTRIBUTES, &attrib_ct);
const GLint input_ct = uniform_ct + attrib_ct;
GLint max_uniform_name_len, max_attrib_name_len;
glGetProgramiv(program, GL_ACTIVE_UNIFORM_MAX_LENGTH, &max_uniform_name_len);
glGetProgramiv(program, GL_ACTIVE_ATTRIBUTE_MAX_LENGTH, &max_attrib_name_len);
const uint32_t name_buffer_len = uniform_ct * max_uniform_name_len + attrib_ct * max_attrib_name_len;
// allocate enough space for input counts, details for each input, and a buffer for name strings
ShaderInterface* shaderface = calloc(1, offsetof(ShaderInterface, inputs) + input_ct * sizeof(ShaderInput) + name_buffer_len);
shaderface->uniform_ct = uniform_ct;
shaderface->attrib_ct = attrib_ct;
char* name_buffer = (char*)shaderface + offsetof(ShaderInterface, inputs) + input_ct * sizeof(ShaderInput);
uint32_t name_buffer_offset = 0;
for (uint32_t i = 0; i < uniform_ct; ++i)
{
ShaderInput* input = shaderface->inputs + i;
GLsizei remaining_buffer = name_buffer_len - name_buffer_offset;
char* name = name_buffer + name_buffer_offset;
GLsizei name_len = 0;
glGetActiveUniform(program, i, remaining_buffer, &name_len, &input->size, &input->gl_type, name);
input->location = glGetUniformLocation(program, name);
#if SUPPORT_LEGACY_GLSL
if (input->location != -1)
{
#elif TRUST_NO_ONE
assert(input->location != -1);
#endif
if (setup_builtin_uniform(input, name))
; // reclaim space from name buffer (don't advance offset)
else
{
set_input_name(input, name);
name_buffer_offset += name_len + 1; // include NULL terminator
}
#if SUPPORT_LEGACY_GLSL
}
#endif
#if DEBUG_SHADER_INTERFACE
printf("uniform[%u] '%s' at location %d\n", i, name, input->location);
#endif
}
for (uint32_t i = 0; i < attrib_ct; ++i)
{
ShaderInput* input = shaderface->inputs + uniform_ct + i;
GLsizei remaining_buffer = name_buffer_len - name_buffer_offset;
char* name = name_buffer + name_buffer_offset;
GLsizei name_len = 0;
glGetActiveAttrib(program, i, remaining_buffer, &name_len, &input->size, &input->gl_type, name);
// TODO: reject DOUBLE gl_types
input->location = glGetAttribLocation(program, name);
#if SUPPORT_LEGACY_GLSL
if (input->location != -1)
{
#elif TRUST_NO_ONE
assert(input->location != -1);
#endif
set_input_name(input, name);
name_buffer_offset += name_len + 1; // include NULL terminator
#if SUPPORT_LEGACY_GLSL
}
#endif
#if DEBUG_SHADER_INTERFACE
printf("attrib[%u] '%s' at location %d\n", i, name, input->location);
#endif
}
const uint32_t name_buffer_used = name_buffer_offset;
#if DEBUG_SHADER_INTERFACE
printf("using %u of %u bytes from name buffer\n", name_buffer_used, name_buffer_len);
printf("}\n"); // exit function
#endif
if (name_buffer_used < name_buffer_len)
{
// realloc shaderface to shrink name buffer
const size_t shaderface_alloc =
offsetof(ShaderInterface, inputs) + (input_ct * sizeof(ShaderInput)) + name_buffer_used;
const char* shaderface_orig_start = (const char*)shaderface;
const char* shaderface_orig_end = &shaderface_orig_start[shaderface_alloc];
shaderface = realloc(shaderface, shaderface_alloc);
const ptrdiff_t delta = (char*)shaderface - shaderface_orig_start;
if (delta)
{
// each input->name will need adjustment (except static built-in names)
for (uint32_t i = 0; i < input_ct; ++i)
{
ShaderInput* input = shaderface->inputs + i;
if (input->name >= shaderface_orig_start && input->name < shaderface_orig_end)
input->name += delta;
}
}
}
return shaderface;
}
void ShaderInterface_discard(ShaderInterface* shaderface)
{
// allocated as one chunk, so discard is simple
free(shaderface);
}
const ShaderInput* ShaderInterface_uniform(const ShaderInterface* shaderface, const char* name)
{
const unsigned name_hash = hash_string(name);
for (uint32_t i = 0; i < shaderface->uniform_ct; ++i)
{
const ShaderInput* uniform = shaderface->inputs + i;
#if SUPPORT_LEGACY_GLSL
if (uniform->name == NULL) continue;
#endif
if (uniform->name_hash != name_hash) continue;
if (match(uniform->name, name))
return uniform;
// TODO: warn if we find a matching builtin, since these can be looked up much quicker --v
}
return NULL; // not found
}
const ShaderInput* ShaderInterface_builtin_uniform(const ShaderInterface* shaderface, BuiltinUniform builtin)
{
#if TRUST_NO_ONE
assert(builtin != UNIFORM_NONE);
assert(builtin != UNIFORM_CUSTOM);
#endif
// look up by enum, not name
for (uint32_t i = 0; i < shaderface->uniform_ct; ++i)
{
const ShaderInput* uniform = shaderface->inputs + i;
if (uniform->builtin_type == builtin)
return uniform;
}
return NULL; // not found
}
const ShaderInput* ShaderInterface_attrib(const ShaderInterface* shaderface, const char* name)
{
// attribs are stored after uniforms
const uint32_t input_ct = shaderface->uniform_ct + shaderface->attrib_ct;
const unsigned name_hash = hash_string(name);
for (uint32_t i = shaderface->uniform_ct; i < input_ct; ++i)
{
const ShaderInput* attrib = shaderface->inputs + i;
#if SUPPORT_LEGACY_GLSL
if (attrib->name == NULL) continue;
#endif
if (attrib->name_hash != name_hash) continue;
if (match(attrib->name, name))
return attrib;
}
return NULL; // not found
}
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