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[0ad.git] / source / lib / ogl.cpp

/* Copyright (C) 2017 Wildfire Games.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

/*
 * OpenGL helper functions.
 */

#include "precompiled.h"
#include "lib/ogl.h"

#include <stdio.h>
#include <string.h>
#include <stdarg.h>

#include "lib/external_libraries/libsdl.h"
#include "lib/debug.h"
#include "lib/sysdep/gfx.h"
#include "lib/res/h_mgr.h"

#if MSC_VERSION
#pragma comment(lib, "opengl32.lib")
#endif


//----------------------------------------------------------------------------
// extensions
//----------------------------------------------------------------------------

// define extension function pointers
extern "C"
{
#define FUNC(ret, name, params) ret (GL_CALL_CONV *p##name) params;
#define FUNC2(ret, nameARB, nameCore, version, params) ret (GL_CALL_CONV *p##nameARB) params;
#define FUNC3(ret, nameARB, nameCore, version, params) ret (GL_CALL_CONV *p##nameCore) params;
#include "lib/external_libraries/glext_funcs.h"
#undef FUNC3
#undef FUNC2
#undef FUNC
}


static const char* exts = NULL;
static bool have_30, have_21, have_20, have_15, have_14, have_13, have_12;


// return a C string of unspecified length containing a space-separated
// list of all extensions the OpenGL implementation advertises.
// (useful for crash logs).
const char* ogl_ExtensionString()
{
        ENSURE(exts && "call ogl_Init before using this function");
        return exts;
}


// paranoia: newer drivers may forget to advertise an extension
// indicating support for something that has been folded into the core.
// we therefore check for all extensions known to be offered by the
// GL implementation present on the user's system; ogl_HaveExtension will
// take this into account.
// the app can therefore just ask for extensions and not worry about this.
static bool isImplementedInCore(const char* ext)
{
#define MATCH(known_ext)\
        if(!strcmp(ext, #known_ext))\
                return true;

        if(have_30)
        {
                MATCH(GL_EXT_gpu_shader4);
                MATCH(GL_NV_conditional_render);
                MATCH(GL_ARB_color_buffer_float);
                MATCH(GL_ARB_depth_buffer_float);
                MATCH(GL_ARB_texture_float);
                MATCH(GL_EXT_packed_float);
                MATCH(GL_EXT_texture_shared_exponent);
                MATCH(GL_EXT_framebuffer_object);
                MATCH(GL_NV_half_float);
                MATCH(GL_ARB_half_float_pixel);
                MATCH(GL_EXT_framebuffer_multisample);
                MATCH(GL_EXT_framebuffer_blit);
                MATCH(GL_EXT_texture_integer);
                MATCH(GL_EXT_texture_array);
                MATCH(GL_EXT_packed_depth_stencil);
                MATCH(GL_EXT_draw_buffers2);
                MATCH(GL_EXT_texture_compression_rgtc);
                MATCH(GL_EXT_transform_feedback);
                MATCH(GL_APPLE_vertex_array_object);
                MATCH(GL_EXT_framebuffer_sRGB);
        }
        if(have_21)
        {
                MATCH(GL_ARB_pixel_buffer_object);
                MATCH(GL_EXT_texture_sRGB);
        }
        if(have_20)
        {
                MATCH(GL_ARB_shader_objects);
                MATCH(GL_ARB_vertex_shader);
                MATCH(GL_ARB_fragment_shader);
                MATCH(GL_ARB_shading_language_100);
                MATCH(GL_ARB_draw_buffers);
                MATCH(GL_ARB_texture_non_power_of_two);
                MATCH(GL_ARB_point_sprite);
                MATCH(GL_EXT_blend_equation_separate);
        }
        if(have_15)
        {
                MATCH(GL_ARB_vertex_buffer_object);
                MATCH(GL_ARB_occlusion_query);
                MATCH(GL_EXT_shadow_funcs);
        }
        if(have_14)
        {
                MATCH(GL_SGIS_generate_mipmap);
                MATCH(GL_NV_blend_square);
                MATCH(GL_ARB_depth_texture);
                MATCH(GL_ARB_shadow);
                MATCH(GL_EXT_fog_coord);
                MATCH(GL_EXT_multi_draw_arrays);
                MATCH(GL_ARB_point_parameters);
                MATCH(GL_EXT_secondary_color);
                MATCH(GL_EXT_blend_func_separate);
                MATCH(GL_EXT_stencil_wrap);
                MATCH(GL_ARB_texture_env_crossbar);
                MATCH(GL_EXT_texture_lod_bias);
                MATCH(GL_ARB_texture_mirrored_repeat);
                MATCH(GL_ARB_window_pos);

                // These extensions were added to GL 1.2, but as part of the optional
                // imaging subset; they're only guaranteed as of GL 1.4:
                MATCH(GL_EXT_blend_color);
                MATCH(GL_EXT_blend_minmax);
                MATCH(GL_EXT_blend_subtract);
        }
        if(have_13)
        {
                MATCH(GL_ARB_texture_compression);
                MATCH(GL_ARB_texture_cube_map);
                MATCH(GL_ARB_multisample);
                MATCH(GL_ARB_multitexture);
                MATCH(GL_ARB_transpose_matrix);
                MATCH(GL_ARB_texture_env_add);
                MATCH(GL_ARB_texture_env_combine);
                MATCH(GL_ARB_texture_env_dot3);
                MATCH(GL_ARB_texture_border_clamp);
        }
        if(have_12)
        {
                MATCH(GL_EXT_texture3D);
                MATCH(GL_EXT_bgra);
                MATCH(GL_EXT_packed_pixels);
                MATCH(GL_EXT_rescale_normal);
                MATCH(GL_EXT_separate_specular_color);
                MATCH(GL_SGIS_texture_edge_clamp);
                MATCH(GL_SGIS_texture_lod);
                MATCH(GL_EXT_draw_range_elements);
                // Skip the extensions that only affect the imaging subset
        }

#undef MATCH
        return false;
}


// check if the extension <ext> is supported by the OpenGL implementation.
// takes subsequently added core support for some extensions into account.
bool ogl_HaveExtension(const char* ext)
{
        ENSURE(exts && "call ogl_Init before using this function");

        if(isImplementedInCore(ext))
                return true;

        const char *p = exts, *end;

        // make sure ext is valid & doesn't contain spaces
        if(!ext || ext[0] == '\0' || strchr(ext, ' '))
                return false;

        for(;;)
        {
                p = strstr(p, ext);
                if(!p)
                        return false; // <ext> string not found - extension not supported
                end = p + strlen(ext); // end of current substring

                // make sure the substring found is an entire extension string,
                // i.e. it starts and ends with ' '
                if((p == exts || p[-1] == ' ') &&       // valid start AND
                   (*end == ' ' || *end == '\0'))       // valid end
                        return true;
                p = end;
        }
}


// check if the OpenGL implementation is at least at <version>.
// (format: "%d.%d" major minor)
bool ogl_HaveVersion(const char* desired_version)
{
        int desired_major, desired_minor;
        if(sscanf_s(desired_version, "%d.%d", &desired_major, &desired_minor) != 2)
        {
                DEBUG_WARN_ERR(ERR::LOGIC);     // invalid version string
                return false;
        }

        // guaranteed to be of the form "major.minor[.release][ vendor-specific]"
        // or "OpenGL ES major.minor[.release][ vendor-specific]".
        // we won't distinguish GLES 2.0 from GL 2.0, but that's okay since
        // they're close enough.
        const char* version = (const char*)glGetString(GL_VERSION);
        int major, minor;
        if(!version ||
            (sscanf_s(version, "%d.%d", &major, &minor) != 2 &&
                 sscanf_s(version, "OpenGL ES %d.%d", &major, &minor) != 2))
        {
                DEBUG_WARN_ERR(ERR::LOGIC);     // GL_VERSION invalid
                return false;
        }

        // note: don't just compare characters - major and minor may be >= 10.
        return (major > desired_major) ||
               (major == desired_major && minor >= desired_minor);
}


// check if all given extension strings (passed as const char* parameters,
// terminated by a 0 pointer) are supported by the OpenGL implementation,
// as determined by ogl_HaveExtension.
// returns 0 if all are present; otherwise, the first extension in the
// list that's not supported (useful for reporting errors).
//
// note: dummy parameter is necessary to access parameter va_list.
//
//
// rationale: this interface is more convenient than individual
// ogl_HaveExtension calls and allows reporting which extension is missing.
//
// one disadvantage is that there is no way to indicate that either one
// of 2 extensions would be acceptable, e.g. (ARB|EXT)_texture_env_dot3.
// this is isn't so bad, since they wouldn't be named differently
// if there weren't non-trivial changes between them. for that reason,
// we refrain from equivalence checks (which would boil down to
// string-matching known extensions to their equivalents).
const char* ogl_HaveExtensions(int dummy, ...)
{
        const char* ext;

        va_list args;
        va_start(args, dummy);
        for(;;)
        {
                ext = va_arg(args, const char*);
                // end of list reached; all were present => return 0.
                if(!ext)
                        break;

                // not found => return name of missing extension.
                if(!ogl_HaveExtension(ext))
                        break;
        }
        va_end(args);

        return ext;
}


// to help when running with no hardware acceleration and only OpenGL 1.1
// (e.g. testing the game in virtual machines), we define dummy versions of
// some extension functions which our graphics code assumes exist.
// it will render incorrectly but at least it shouldn't crash.

#if CONFIG2_GLES

static void enableDummyFunctions()
{
}

#else

static void GL_CALL_CONV dummy_glDrawRangeElementsEXT(GLenum mode, GLuint, GLuint, GLsizei count, GLenum type, GLvoid* indices)
{
        glDrawElements(mode, count, type, indices);
}

static void GL_CALL_CONV dummy_glActiveTextureARB(int)
{
}

static void GL_CALL_CONV dummy_glClientActiveTextureARB(int)
{
}

static void GL_CALL_CONV dummy_glMultiTexCoord2fARB(int, float s, float t)
{
        glTexCoord2f(s, t);
}

static void GL_CALL_CONV dummy_glMultiTexCoord3fARB(int, float s, float t, float r)
{
        glTexCoord3f(s, t, r);
}

static void enableDummyFunctions()
{
        // fall back to the dummy functions when extensions (or equivalent core support) are missing

        if(!ogl_HaveExtension("GL_EXT_draw_range_elements"))
        {
                pglDrawRangeElementsEXT = &dummy_glDrawRangeElementsEXT;
        }

        if(!ogl_HaveExtension("GL_ARB_multitexture"))
        {
                pglActiveTextureARB = &dummy_glActiveTextureARB;
                pglClientActiveTextureARB = &dummy_glClientActiveTextureARB;
                pglMultiTexCoord2fARB = &dummy_glMultiTexCoord2fARB;
                pglMultiTexCoord3fARB = &dummy_glMultiTexCoord3fARB;
        }
}

#endif  // #if CONFIG2_GLES

static void importExtensionFunctions()
{
        // It should be safe to load the ARB function pointers even if the
        // extension isn't advertised, since we won't actually use them without
        // checking for the extension.
        // (TODO: this calls ogl_HaveVersion far more times than is necessary -
        // we should probably use the have_* variables instead)
        // Note: the xorg-x11 implementation of glXGetProcAddress doesn't return NULL
        //   if the function is unsupported (i.e. the rare case of a driver not reporting
        //   its supported version correctly, see http://trac.wildfiregames.com/ticket/171)
#define FUNC(ret, name, params) p##name = (ret (GL_CALL_CONV*) params)SDL_GL_GetProcAddress(#name);
#define FUNC23(pname, ret, nameARB, nameCore, version, params) \
        pname = NULL; \
        if(ogl_HaveVersion(version)) \
                pname = (ret (GL_CALL_CONV*) params)SDL_GL_GetProcAddress(#nameCore); \
        if(!pname) /* use the ARB name if the driver lied about what version it supports */ \
                pname = (ret (GL_CALL_CONV*) params)SDL_GL_GetProcAddress(#nameARB);
#define FUNC2(ret, nameARB, nameCore, version, params) FUNC23(p##nameARB, ret, nameARB, nameCore, version, params)
#define FUNC3(ret, nameARB, nameCore, version, params) FUNC23(p##nameCore, ret, nameARB, nameCore, version, params)
#include "lib/external_libraries/glext_funcs.h"
#undef FUNC3
#undef FUNC2
#undef FUNC23
#undef FUNC

        enableDummyFunctions();
}


//----------------------------------------------------------------------------

const char* ogl_GetErrorName(GLenum err)
{
#define E(e) case e: return #e;
        switch (err)
        {
        E(GL_INVALID_ENUM)
        E(GL_INVALID_VALUE)
        E(GL_INVALID_OPERATION)
#if !CONFIG2_GLES
        E(GL_STACK_OVERFLOW)
        E(GL_STACK_UNDERFLOW)
#endif
        E(GL_OUT_OF_MEMORY)
        E(GL_INVALID_FRAMEBUFFER_OPERATION)
        default: return "Unknown GL error";
        }
#undef E
}

static void dump_gl_error(GLenum err)
{
        debug_printf("OGL| %s (%04x)\n", ogl_GetErrorName(err), err);
}

void ogl_WarnIfErrorLoc(const char *file, int line)
{
        // glGetError may return multiple errors, so we poll it in a loop.
        // the debug_printf should only happen once (if this is set), though.
        bool error_enountered = false;
        GLenum first_error = 0;

        for(;;)
        {
                GLenum err = glGetError();
                if(err == GL_NO_ERROR)
                        break;

                if(!error_enountered)
                        first_error = err;

                error_enountered = true;
                dump_gl_error(err);
        }

        if(error_enountered)
                debug_printf("%s:%d: OpenGL error(s) occurred: %s (%04x)\n", file, line, ogl_GetErrorName(first_error), (unsigned int)first_error);
}


// ignore and reset the specified error (as returned by glGetError).
// any other errors that have occurred are reported as ogl_WarnIfError would.
//
// this is useful for suppressing annoying error messages, e.g.
// "invalid enum" for GL_CLAMP_TO_EDGE even though we've already
// warned the user that their OpenGL implementation is too old.
bool ogl_SquelchError(GLenum err_to_ignore)
{
        // glGetError may return multiple errors, so we poll it in a loop.
        // the debug_printf should only happen once (if this is set), though.
        bool error_enountered = false;
        bool error_ignored = false;
        GLenum first_error = 0;

        for(;;)
        {
                GLenum err = glGetError();
                if(err == GL_NO_ERROR)
                        break;

                if(err == err_to_ignore)
                {
                        error_ignored = true;
                        continue;
                }

                if(!error_enountered)
                        first_error = err;

                error_enountered = true;
                dump_gl_error(err);
        }

        if(error_enountered)
                debug_printf("OpenGL error(s) occurred: %04x\n", (unsigned int)first_error);

        return error_ignored;
}


//----------------------------------------------------------------------------
// feature and limit detect
//----------------------------------------------------------------------------

GLint ogl_max_tex_size = -1;                            // [pixels]
GLint ogl_max_tex_units = -1;                           // limit on GL_TEXTUREn

// call after each video mode change, since thereafter extension functions
// may have changed [address].
void ogl_Init()
{
        // cache extension list and versions for oglHave*.
        // note: this is less about performance (since the above are not
        // time-critical) than centralizing the 'OpenGL is ready' check.
        exts = (const char*)glGetString(GL_EXTENSIONS);
        ENSURE(exts);   // else: called before OpenGL is ready for use
        have_12 = ogl_HaveVersion("1.2");
        have_13 = ogl_HaveVersion("1.3");
        have_14 = ogl_HaveVersion("1.4");
        have_15 = ogl_HaveVersion("1.5");
        have_20 = ogl_HaveVersion("2.0");
        have_21 = ogl_HaveVersion("2.1");
        have_30 = ogl_HaveVersion("3.0");

        importExtensionFunctions();

        glGetIntegerv(GL_MAX_TEXTURE_SIZE, &ogl_max_tex_size);
#if !CONFIG2_GLES
        glGetIntegerv(GL_MAX_TEXTURE_UNITS, &ogl_max_tex_units);
#endif
}