r_state.cpp

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/*
Copyright (C) 1997-2001 Id Software, Inc.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/

#include "r_local.h"
#include "r_program.h"
#include "r_error.h"

/* useful for particles, pics, etc.. */
const vec2_t default_texcoords[4] = {
    {0.0, 0.0}, {1.0, 0.0}, {1.0, 1.0}, {0.0, 1.0}
};

/* Hack to keep track of active rendering program (have to reinit binings&parameters once it changed)*/
static r_program_t* lastProgram = nullptr;

bool R_SelectTexture (gltexunit_t* texunit)
{
    if (texunit == r_state.active_texunit)
        return true;

    /* not supported */
    if (texunit->texture >= r_config.maxTextureCoords + GL_TEXTURE0)
        return false;

    r_state.active_texunit = texunit;

    qglActiveTexture(texunit->texture);
    qglClientActiveTexture(texunit->texture);
    return true;
}

static void R_BindTexture_ (int texnum)
{
    if (texnum == r_state.active_texunit->texnum)
        return;

    assert(texnum > 0);

    r_state.active_texunit->texnum = texnum;

    glBindTexture(GL_TEXTURE_2D, texnum);
    R_CheckError();
}

void R_BindTextureDebug (int texnum, const char* file, int line, const char* function)
{
    if (texnum <= 0) {
        Com_Printf("Bad texnum (%d) in: %s (%d): %s\n", texnum, file, line, function);
    }
    R_BindTexture_(texnum);
}

void R_BindTextureForTexUnit (GLuint texnum, gltexunit_t* texunit)
{
    /* small optimization to save state changes */
    if (texnum == texunit->texnum)
        return;

    R_SelectTexture(texunit);

    R_BindTexture(texnum);

    R_SelectTexture(&texunit_diffuse);
}

void R_BindLightmapTexture (GLuint texnum)
{
    R_BindTextureForTexUnit(texnum, &texunit_lightmap);
}

void R_BindDeluxemapTexture (GLuint texnum)
{
    R_BindTextureForTexUnit(texnum, &texunit_deluxemap);
}

void R_BindNormalmapTexture (GLuint texnum)
{
    R_BindTextureForTexUnit(texnum, &texunit_normalmap);
}

void R_UseMaterial (const material_t* material)
{
    static float last_b, last_p, last_s, last_h;
    float b;

    if (r_state.active_material == material)
        return;

    if (!r_state.active_normalmap)
        return;

    if (material)
        r_state.active_material = material;
    else
        r_state.active_material = &defaultMaterial;

    b = r_state.active_material->bump * r_bumpmap->value;
    if (b != last_b)
        R_ProgramParameter1f("BUMP", b);
    last_b = b;

    if (r_state.active_program != r_state.world_program || r_programs->integer > 1) {
        const float p = r_state.active_material->parallax * r_parallax->value;
        if (p != last_p)
            R_ProgramParameter1f("PARALLAX", p);
        last_p = p;

        const float h = r_state.active_material->hardness * r_hardness->value;
        if (h != last_h)
            R_ProgramParameter1f("HARDNESS", h);
        last_h = h;

        const float s = r_state.active_material->specular * r_specular->value;
        if (s != last_s)
            R_ProgramParameter1f("SPECULAR", s);
        last_s = s;
    } else {
        last_p = -1;
        last_h = -1;
        last_s = -1;
    }
}

void R_BindArray (GLenum target, GLenum type, const void* array)
{
    const int v = static_cast<int>(target);
    switch (v) {
    case GL_VERTEX_ARRAY:
        glVertexPointer(COMPONENTS_VERTEX_ARRAY3D, type, 0, array);
        break;
    case GL_TEXTURE_COORD_ARRAY:
        glTexCoordPointer(COMPONENTS_TEXCOORD_ARRAY, type, 0, array);
        break;
    case GL_COLOR_ARRAY:
        glColorPointer(COMPONENTS_COLOR_ARRAY, type, 0, array);
        break;
    case GL_NORMAL_ARRAY:
        glNormalPointer(type, 0, array);
        break;
    case GL_TANGENT_ARRAY:
        R_AttributePointer("TANGENTS", COMPONENTS_TANGENT_ARRAY, array);
        break;
    case GL_NEXT_VERTEX_ARRAY:
        R_AttributePointer("NEXT_FRAME_VERTS", COMPONENTS_VERTEX_ARRAY3D, array);
        break;
    case GL_NEXT_NORMAL_ARRAY:
        R_AttributePointer("NEXT_FRAME_NORMALS", COMPONENTS_NORMAL_ARRAY, array);
        break;
    case GL_NEXT_TANGENT_ARRAY:
        R_AttributePointer("NEXT_FRAME_TANGENTS", COMPONENTS_TANGENT_ARRAY, array);
        break;
    }
}

void R_BindDefaultArray (GLenum target)
{
    const int v = static_cast<int>(target);
    switch (v) {
    case GL_VERTEX_ARRAY:
        R_BindArray(target, GL_FLOAT, r_state.vertex_array_3d);
        break;
    case GL_TEXTURE_COORD_ARRAY:
        R_BindArray(target, GL_FLOAT, r_state.active_texunit->texcoord_array);
        break;
    case GL_COLOR_ARRAY:
        R_BindArray(target, GL_FLOAT, r_state.color_array);
        break;
    case GL_NORMAL_ARRAY:
        R_BindArray(target, GL_FLOAT, r_state.normal_array);
        break;
    case GL_TANGENT_ARRAY:
        R_BindArray(target, GL_FLOAT, r_state.tangent_array);
        break;
    case GL_NEXT_VERTEX_ARRAY:
        R_BindArray(target, GL_FLOAT, r_state.next_vertex_array_3d);
        break;
    case GL_NEXT_NORMAL_ARRAY:
        R_BindArray(target, GL_FLOAT, r_state.next_normal_array);
        break;
    case GL_NEXT_TANGENT_ARRAY:
        R_BindArray(target, GL_FLOAT, r_state.next_tangent_array);
        break;
    }
}

void R_BindBuffer (GLenum target, GLenum type, GLuint id)
{
    if (!qglBindBuffer)
        return;

    if (!r_vertexbuffers->integer)
        return;

    if (target == GL_ELEMENT_ARRAY_BUFFER) {
        qglBindBuffer(GL_ELEMENT_ARRAY_BUFFER, id);
        return; /* No need to call gl***Poiner -- this binding is special and automates that */
    } else {
        qglBindBuffer(GL_ARRAY_BUFFER, id);
    }

    if (type && id)  /* assign the array pointer as well */
        R_BindArray(target, type, nullptr);
}

void R_BlendFunc (GLenum src, GLenum dest)
{
    if (r_state.blend_src == src && r_state.blend_dest == dest)
        return;

    r_state.blend_src = src;
    r_state.blend_dest = dest;

    glBlendFunc(src, dest);
}

void R_EnableMultisample (bool enable)
{
    if (r_multisample->integer == 0 && enable)
        return;

    if (r_state.multisample_enabled == enable)
        return;

    r_state.multisample_enabled = enable;

    if (enable) {
        glEnable(GL_MULTISAMPLE);
    } else {
        glDisable(GL_MULTISAMPLE);
    }
    R_CheckError();
}

void R_EnableBlend (bool enable)
{
    if (r_state.blend_enabled == enable)
        return;

    r_state.blend_enabled = enable;

    if (enable) {
        glEnable(GL_BLEND);
        glDepthMask(GL_FALSE);
    } else {
        glDisable(GL_BLEND);
        glDepthMask(GL_TRUE);
    }
}

void R_EnableAlphaTest (bool enable)
{
    if (r_state.alpha_test_enabled == enable)
        return;

    r_state.alpha_test_enabled = enable;

    if (enable)
        glEnable(GL_ALPHA_TEST);
    else
        glDisable(GL_ALPHA_TEST);
}

void R_EnableStencilTest (bool enable)
{
    if (r_state.stencil_test_enabled == enable)
        return;

    r_state.stencil_test_enabled = enable;

    if (enable)
        glEnable(GL_STENCIL_TEST);
    else
        glDisable(GL_STENCIL_TEST);
}

void R_EnableTexture (gltexunit_t* texunit, bool enable)
{
    if (enable == texunit->enabled)
        return;

    texunit->enabled = enable;

    R_SelectTexture(texunit);

    if (enable) {
        /* activate texture unit */
        glEnable(GL_TEXTURE_2D);

        glEnableClientState(GL_TEXTURE_COORD_ARRAY);

        if (texunit == &texunit_lightmap) {
            if (r_lightmap->integer)
                R_TexEnv(GL_REPLACE);
            else
                R_TexEnv(GL_MODULATE);
        }
    } else {
        /* disable on the second texture unit */
        glDisable(GL_TEXTURE_2D);
        glDisableClientState(GL_TEXTURE_COORD_ARRAY);
    }
    R_SelectTexture(&texunit_diffuse);
}

void R_EnableColorArray (bool enable)
{
    if (r_state.color_array_enabled == enable)
        return;

    r_state.color_array_enabled = enable;

    if (enable)
        glEnableClientState(GL_COLOR_ARRAY);
    else
        glDisableClientState(GL_COLOR_ARRAY);
}

bool R_EnableLighting (r_program_t* program, bool enable)
{
    if (!r_programs->integer)
        return r_state.lighting_enabled;

    if (enable && (!program || !program->id))
        return r_state.lighting_enabled;

    if (r_state.lighting_enabled == enable && r_state.active_program == program)
        return r_state.lighting_enabled;

    r_state.lighting_enabled = enable;

    if (enable) {  /* toggle state */
        R_UseProgram(program);

        glEnableClientState(GL_NORMAL_ARRAY);
    } else {
        glDisableClientState(GL_NORMAL_ARRAY);

        R_UseProgram(nullptr);
    }

    return r_state.lighting_enabled;
}

void R_SetupSpotLight (int index, const light_t* light)
{
    const vec4_t blackColor = {0.0, 0.0, 0.0, 1.0};
    vec4_t position;

    if (!r_programs->integer || !r_dynamic_lights->integer)
        return;

    if (index < 0 || index >= r_dynamic_lights->integer)
        return;

    index += GL_LIGHT0;

    glEnable(index);
    glLightf(index, GL_CONSTANT_ATTENUATION, MIN_GL_CONSTANT_ATTENUATION);
    glLightf(index, GL_LINEAR_ATTENUATION, 0);
    glLightf(index, GL_QUADRATIC_ATTENUATION, 16.0 / (light->radius * light->radius));

    VectorCopy(light->origin, position);
    position[3] = 1.0; /* spot light */

    glLightfv(index, GL_POSITION, position);
    glLightfv(index, GL_AMBIENT, blackColor);
    glLightfv(index, GL_DIFFUSE, light->color);
    glLightfv(index, GL_SPECULAR, blackColor);
}

void R_DisableSpotLight (int index)
{
    const vec4_t blackColor = {0.0, 0.0, 0.0, 1.0};

    if (!r_programs->integer || !r_dynamic_lights)
        return;

    if (index < 0 || index >= MAX_GL_LIGHTS - 1)
        return;

    index += GL_LIGHT0;

    glDisable(index);
    glLightf(index, GL_CONSTANT_ATTENUATION, MIN_GL_CONSTANT_ATTENUATION);
    glLightf(index, GL_LINEAR_ATTENUATION, 0.0);
    glLightf(index, GL_QUADRATIC_ATTENUATION, 0.0);
    glLightfv(index, GL_AMBIENT, blackColor);
    glLightfv(index, GL_DIFFUSE, blackColor);
    glLightfv(index, GL_SPECULAR, blackColor);
}

void R_EnableAnimation (const mAliasMesh_t* mesh, float backlerp, bool enable)
{
    if (!r_programs->integer || !r_state.lighting_enabled)
        return;

    r_state.animation_enabled = enable;

    if (enable) {
        R_EnableAttribute("NEXT_FRAME_VERTS");
        R_EnableAttribute("NEXT_FRAME_NORMALS");
        R_EnableAttribute("NEXT_FRAME_TANGENTS");
        R_ProgramParameter1i("ANIMATE", 1);

        R_ProgramParameter1f("TIME", backlerp);

        R_BindArray(GL_TEXTURE_COORD_ARRAY, GL_FLOAT, mesh->texcoords);
        R_BindArray(GL_VERTEX_ARRAY, GL_FLOAT, mesh->verts);
        R_BindArray(GL_NORMAL_ARRAY, GL_FLOAT, mesh->normals);
        R_BindArray(GL_TANGENT_ARRAY, GL_FLOAT, mesh->tangents);
        R_BindArray(GL_NEXT_VERTEX_ARRAY, GL_FLOAT, mesh->next_verts);
        R_BindArray(GL_NEXT_NORMAL_ARRAY, GL_FLOAT, mesh->next_normals);
        R_BindArray(GL_NEXT_TANGENT_ARRAY, GL_FLOAT, mesh->next_tangents);
    } else {
        R_DisableAttribute("NEXT_FRAME_VERTS");
        R_DisableAttribute("NEXT_FRAME_NORMALS");
        R_DisableAttribute("NEXT_FRAME_TANGENTS");
        R_ProgramParameter1i("ANIMATE", 0);
    }
}

void R_EnableBumpmap (const image_t* normalmap)
{
    if (!r_state.lighting_enabled)
        return;

    if (!r_bumpmap->value)
        return;

    if (r_state.active_normalmap == normalmap)
        return;

    if (!normalmap) {
        /* disable bump mapping */
        R_ProgramParameter1i("BUMPMAP", 0);

        r_state.active_normalmap = normalmap;
        return;
    }

    if (!r_state.active_normalmap) {
        /* enable bump mapping */
        R_ProgramParameter1i("BUMPMAP", 1);
        /* default material to use if no material gets loaded */
        R_UseMaterial(&defaultMaterial);
    }

    R_BindNormalmapTexture(normalmap->texnum);

    r_state.active_normalmap = normalmap;
}

void R_EnableWarp (r_program_t* program, bool enable)
{
    if (!r_programs->integer)
        return;

    if (enable && (!program || !program->id))
        return;

    if (!r_warp->integer || r_state.warp_enabled == enable)
        return;

    r_state.warp_enabled = enable;

    R_SelectTexture(&texunit_lightmap);

    if (enable) {
        glEnable(GL_TEXTURE_2D);
        R_BindTexture(r_warpTexture->texnum);
        R_UseProgram(program);
    } else {
        glDisable(GL_TEXTURE_2D);
        R_UseProgram(nullptr);
    }

    R_SelectTexture(&texunit_diffuse);
}

void R_EnableBlur (r_program_t* program, bool enable, r_framebuffer_t* source, r_framebuffer_t* dest, int dir)
{
    if (!r_programs->integer)
        return;

    if (enable && (!program || !program->id))
        return;

    if (!r_postprocess->integer || r_state.blur_enabled == enable)
        return;

    r_state.blur_enabled = enable;

    R_SelectTexture(&texunit_lightmap);

    if (enable) {
        float userdata[] = { static_cast<float>(source->width), static_cast<float>(dir) };
        R_UseFramebuffer(dest);
        program->userdata = userdata;
        R_UseProgram(program);
    } else {
        R_UseFramebuffer(fbo_screen);
        R_UseProgram(nullptr);
    }

    R_SelectTexture(&texunit_diffuse);
}

void R_EnableShell (bool enable)
{
    if (enable == r_state.shell_enabled)
        return;

    r_state.shell_enabled = enable;

    if (enable) {
        glEnable(GL_POLYGON_OFFSET_FILL);
        glPolygonOffset(-1.0, 1.0);

        R_EnableDrawAsGlow(true);
        R_EnableBlend(true);
        R_BlendFunc(GL_SRC_ALPHA, GL_ONE);

        if (r_state.lighting_enabled)
            R_ProgramParameter1f("OFFSET", refdef.time / 3.0);
    } else {
        R_BlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
        R_EnableBlend(false);
        R_EnableDrawAsGlow(false);

        glPolygonOffset(0.0, 0.0);
        glDisable(GL_POLYGON_OFFSET_FILL);

        if (r_state.lighting_enabled)
            R_ProgramParameter1f("OFFSET", 0.0);
    }
}

#define FOG_START   300.0
#define FOG_END     2500.0

vec2_t fogRange = {FOG_START, FOG_END};

void R_EnableFog (bool enable)
{
    if (!r_fog->integer || r_state.fog_enabled == enable)
        return;

    r_state.fog_enabled = false;

    /* This is ugly. Shaders could be enabled or disabled between this and rendering call, so we have to setup both FFP and GLSL */
    if (enable) {
        if (((refdef.weather & WEATHER_FOG) && r_fog->integer) || r_fog->integer == 2) {
            r_state.fog_enabled = true;

            glFogfv(GL_FOG_COLOR, refdef.fogColor);
            glFogf(GL_FOG_DENSITY, refdef.fogColor[3]);
            glEnable(GL_FOG);

            if (r_programs->integer && (r_state.active_program == r_state.world_program || r_state.active_program == r_state.model_program || r_state.active_program == r_state.warp_program)) {
                R_ProgramParameter3fv("FOGCOLOR", refdef.fogColor);
                R_ProgramParameter1f("FOGDENSITY", refdef.fogColor[3]);
                R_ProgramParameter2fv("FOGRANGE", fogRange);
            }
        }
    } else {
        glFogf(GL_FOG_DENSITY, 0.0);
        glDisable(GL_FOG);
        if (r_programs->integer && (r_state.active_program == r_state.world_program || r_state.active_program == r_state.model_program || r_state.active_program == r_state.warp_program))
            R_ProgramParameter1f("FOGDENSITY", 0.0f);
    }
}

static void R_UpdateGlowBufferBinding (void)
{
#ifndef GL_VERSION_ES_CM_1_0
    static GLenum glowRenderTarget = GL_COLOR_ATTACHMENT1_EXT; // Not supported in GLES

    if (r_state.active_program) {
        /* got an active shader */
        if (r_state.draw_glow_enabled) {
            /* switch the draw buffer to the glow buffer */
            R_BindColorAttachments(1, &glowRenderTarget);
            R_ProgramParameter1f("GLOWSCALE", 0.0); /* Plumbing to avoid state leak */
        } else {
            /* switch back to the draw buffer we are currently rendering into ... */
            R_DrawBuffers(2);
            /* ... and enable glow, if there is a glow map */
            if (r_state.glowmap_enabled) {
                R_ProgramParameter1f("GLOWSCALE", 1.0);
            } else {
                R_ProgramParameter1f("GLOWSCALE", 0.0);
            }
        }
    } else {
        /* no shader */
        if (r_state.draw_glow_enabled) {
            /* switch the draw buffer to the glow buffer */
            R_BindColorAttachments(1, &glowRenderTarget);
        } else {
            if (!r_state.glowmap_enabled) {
                /* Awkward case. Postprocessing is requested, but fragment
                 * shader is disabled, and we are supposed to draw non-glowing object.
                 * So we just draw this object into color buffer only and hope that it's not
                 * supposed to overlay any glowing objects.
                 */
                R_DrawBuffers(1);
            } else {
                /* FIXME: Had to draw glowmapped object,  but don't know how to do it
                 * when rendering through FFP.
                 * So -- just copy color into glow buffer.
                 * (R_DrawAsGlow may hit this)
                 */
                R_DrawBuffers(2);
                /*Con_Print("GLSL glow with no program!\n");*/
            }
        }
    }
#endif
}

void R_EnableGlowMap (const image_t* image)
{
    if (!r_programs->integer)
        return;

    if (image)
        R_BindTextureForTexUnit(image->texnum, &texunit_glowmap);

    if (!image && r_state.glowmap_enabled == !!image && r_state.active_program == lastProgram)
        return;

    r_state.glowmap_enabled = !!image;

    /* Shouldn't render glow without GLSL, so enable simple program for it */
    if (image) {
        if (!r_state.active_program)
            R_UseProgram(r_state.simple_glow_program);
    } else {
        if (r_state.active_program == r_state.simple_glow_program)
            R_UseProgram(nullptr);
    }

    lastProgram = r_state.active_program;

    R_UpdateGlowBufferBinding();
}

void R_EnableDrawAsGlow (bool enable)
{
    if (!r_programs->integer)
        return;

    if (r_state.draw_glow_enabled == enable && r_state.active_program == lastProgram)
        return;

    r_state.draw_glow_enabled = enable;

    lastProgram = r_state.active_program;

    R_UpdateGlowBufferBinding();
}

void R_EnableSpecularMap (const image_t* image, bool enable)
{
    if (!r_state.dynamic_lighting_enabled)
        return;

    if (r_programs->integer < 2)
        return;

    if (enable && image != nullptr) {
        R_BindTextureForTexUnit(image->texnum, &texunit_specularmap);
        R_ProgramParameter1i("SPECULARMAP", 1);
        r_state.specularmap_enabled = enable;
    } else {
        R_ProgramParameter1i("SPECULARMAP", 0);
        r_state.specularmap_enabled = false;
    }
}

void R_EnableRoughnessMap (const image_t* image, bool enable)
{
    if (!r_state.dynamic_lighting_enabled)
        return;

    if (enable && image != nullptr) {
        R_BindTextureForTexUnit(image->texnum, &texunit_roughnessmap);
        R_ProgramParameter1i("ROUGHMAP", 1);
        r_state.roughnessmap_enabled = enable;
    } else {
        R_ProgramParameter1i("ROUGHMAP", 0);
        r_state.roughnessmap_enabled = false;
    }
}

static void MYgluPerspective (GLfloat zNear, GLfloat zFar)
{
    GLfloat xmin, xmax, ymin, ymax, yaspect = (float) viddef.context.height / viddef.context.width;

    if (r_isometric->integer) {
        glOrtho(-10 * refdef.fieldOfViewX, 10 * refdef.fieldOfViewX, -10 * refdef.fieldOfViewX * yaspect, 10 * refdef.fieldOfViewX * yaspect, -zFar, zFar);
    } else {
        xmax = zNear * tan(refdef.fieldOfViewX * (M_PI / 360.0));
        xmin = -xmax;

        ymin = xmin * yaspect;
        ymax = xmax * yaspect;

        glFrustum(xmin, xmax, ymin, ymax, zNear, zFar);
    }
}

void R_Setup3D (void)
{
    /* only for the battlescape rendering */
    if ((refdef.rendererFlags & RDF_NOWORLDMODEL) == 0) {
        int x, x2, y2, y, w, h;

        /* set up viewport */
        x = floorf(viddef.x * viddef.context.width / viddef.context.width);
        x2 = ceilf((viddef.x + viddef.viewWidth) * viddef.context.width / viddef.context.width);
        y = floorf(viddef.context.height - viddef.y * viddef.context.height / viddef.context.height);
        y2 = ceilf(viddef.context.height - (viddef.y + viddef.viewHeight) * viddef.context.height / viddef.context.height);

        w = x2 - x;
        h = y - y2;

        glViewport(x, y2, w, h);
        R_CheckError();
    }

    /* set up projection matrix */
    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();
    if ((refdef.rendererFlags & RDF_NOWORLDMODEL) != 0) {
        /* center image into the viewport */
        float x = viddef.x + (viddef.viewWidth - VID_NORM_WIDTH) / 2.0 - (viddef.virtualWidth - VID_NORM_WIDTH) / 2.0;
        float y = viddef.y + (viddef.viewHeight - VID_NORM_HEIGHT) / 2.0 - (viddef.virtualHeight - VID_NORM_HEIGHT) / 2.0;
        /* @todo magic coef, i dont know where it come from */
        x *=  2.0f / (float) viddef.virtualWidth;
        y *=  2.0f / (float) viddef.virtualHeight;
        glTranslatef(x, -y, 0.0f);
    }
    MYgluPerspective(4.0, MAX_WORLD_WIDTH);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glRotatef(-90.0, 1.0, 0.0, 0.0);    /* put Z going up */
    glRotatef(90.0, 0.0, 0.0, 1.0); /* put Z going up */
    glRotatef(-refdef.viewAngles[2], 1.0, 0.0, 0.0);
    glRotatef(-refdef.viewAngles[0], 0.0, 1.0, 0.0);
    glRotatef(-refdef.viewAngles[1], 0.0, 0.0, 1.0);
    glTranslatef(-refdef.viewOrigin[0], -refdef.viewOrigin[1], -refdef.viewOrigin[2]);

    /* retrieve the resulting matrix for other manipulations  */
    glGetFloatv(GL_MODELVIEW_MATRIX, r_locals.world_matrix);

    /* set vertex array pointer */
    R_BindDefaultArray(GL_VERTEX_ARRAY);

    glDisable(GL_BLEND);

    glEnable(GL_DEPTH_TEST);

    /* set up framebuffers for postprocessing */
    R_EnableRenderbuffer(true);

    R_CheckError();
}

void R_Setup2D (void)
{
    /* only for the battlescape rendering */
    if ((refdef.rendererFlags & RDF_NOWORLDMODEL) == 0) {
        /* set 2D virtual screen size */
        glViewport(0, 0, viddef.context.width, viddef.context.height);
    }

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    /* switch to orthographic (2 dimensional) projection
     * don't draw anything before skybox */
    glOrtho(0, viddef.context.width, viddef.context.height, 0, 9999.0f, SKYBOX_DEPTH);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    /* bind default vertex array */
    R_BindDefaultArray(GL_VERTEX_ARRAY);

    R_Color(nullptr);

    glEnable(GL_BLEND);

    glDisable(GL_DEPTH_TEST);

    glDisable(GL_LIGHTING);

    /* disable render-to-framebuffer */
    R_EnableRenderbuffer(false);

    R_CheckError();
}

void R_SetDefaultState (void)
{
    r_state.shell_enabled = false;
    r_state.blend_enabled = false;
    r_state.color_array_enabled = false;
    r_state.alpha_test_enabled = false;
    r_state.stencil_test_enabled = false;
    r_state.lighting_enabled = false;
    r_state.warp_enabled = false;
    r_state.fog_enabled = false;
    r_state.blur_enabled = false;
    r_state.glowmap_enabled = false;
    r_state.draw_glow_enabled = false;
    r_state.dynamic_lighting_enabled = false;
    r_state.specularmap_enabled = false;
    r_state.roughnessmap_enabled = false;
    r_state.animation_enabled = false;
    r_state.renderbuffer_enabled = false;
    r_state.active_material = nullptr;
    r_state.blend_src = 0;
    r_state.blend_dest = 0;
    r_state.active_texunit = nullptr;

    glClearColor(0, 0, 0, 0);

    glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);

    R_ReallocateStateArrays(GL_ARRAY_LENGTH_CHUNK);
    R_ReallocateTexunitArray(&texunit_0, GL_ARRAY_LENGTH_CHUNK);
    R_ReallocateTexunitArray(&texunit_1, GL_ARRAY_LENGTH_CHUNK);
    R_ReallocateTexunitArray(&texunit_2, GL_ARRAY_LENGTH_CHUNK);
    R_ReallocateTexunitArray(&texunit_3, GL_ARRAY_LENGTH_CHUNK);
    R_ReallocateTexunitArray(&texunit_4, GL_ARRAY_LENGTH_CHUNK);

    /* setup vertex array pointers */
    glEnableClientState(GL_VERTEX_ARRAY);
    R_BindDefaultArray(GL_VERTEX_ARRAY);

    R_EnableColorArray(true);
    R_BindDefaultArray(GL_COLOR_ARRAY);
    R_EnableColorArray(false);

    glEnableClientState(GL_NORMAL_ARRAY);
    R_BindDefaultArray(GL_NORMAL_ARRAY);
    glDisableClientState(GL_NORMAL_ARRAY);

    R_EnableAlphaTest(false);

    /* reset gl error state */
    R_CheckError();

    /* setup texture units */
    for (int i = 0; i < r_config.maxTextureCoords && i < MAX_GL_TEXUNITS; i++) {
        gltexunit_t* tex = &r_state.texunits[i];
        tex->texture = GL_TEXTURE0 + i;
        tex->enabled = false;

        R_EnableTexture(tex, true);

        R_BindDefaultArray(GL_TEXTURE_COORD_ARRAY);
        R_TexEnv(GL_MODULATE);
        R_ReallocateTexunitArray(tex, GL_ARRAY_LENGTH_CHUNK);

        if (i > 0)  /* turn them off for now */
            R_EnableTexture(tex, false);

        R_CheckError();
    }

    R_SelectTexture(&texunit_diffuse);
    /* alpha test parameters */
    glAlphaFunc(GL_GREATER, 0.01f);

    /* fog parameters */
    glFogi(GL_FOG_MODE, GL_LINEAR);
    glFogf(GL_FOG_START, FOG_START);
    glFogf(GL_FOG_END, FOG_END);

    /* stencil test parameters */
    glStencilFunc(GL_GEQUAL, 1, 0xff);
    glStencilOp(GL_KEEP, GL_KEEP, GL_INCR);

    /* polygon offset parameters */
    glPolygonOffset(1, 1);

    /* alpha blend parameters */
    R_EnableBlend(true);
    R_BlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    /* remove leftover lights */
    R_ClearStaticLights();

    /* reset gl error state */
    R_CheckError();
}

void R_TexEnv (GLenum mode)
{
    if (mode == r_state.active_texunit->texenv)
        return;

    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, mode);
    r_state.active_texunit->texenv = mode;
}

void R_TexOverride (vec4_t rgba)
{
    R_SelectTexture(&texunit_lightmap); /* abuse lightmap texture unit for color manipulation */

    if (!rgba) {
        R_TexEnv(GL_MODULATE);
        glDisable(GL_TEXTURE_2D);
        R_SelectTexture(&texunit_diffuse);
        return;
    }

    glEnable(GL_TEXTURE_2D);

    R_TexEnv(GL_COMBINE); /* enable color combiner */
    /* setup texture combiner to blend between actual color of previous texture stage and the constant rgb color given as the parameter to this function
     * amount of blending is defined by alpha channel of constant color
     */
    glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_CONSTANT); /* set constant color as blending target*/
    glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
    glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_PREVIOUS); /* set incoming color as blending source */
    glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
    glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE2_RGB, GL_CONSTANT); /* set constant color alpha as blending factor */
    glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND2_RGB, GL_SRC_ALPHA);
    glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_INTERPOLATE); /* set blending mode to interpolation from src1 to src0 */
    /* copy alpha from incoming color, it could be used later for framebuffer operations */
    glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE);
    glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_PREVIOUS);
    glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA);

    glTexEnvfv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, rgba);

    R_BindTexture(r_dummyTexture->texnum);

    R_SelectTexture(&texunit_diffuse);
}

const vec4_t color_white = {1, 1, 1, 1};

void R_Color (const vec4_t rgba)
{
    const float* color;
    if (rgba)
        color = rgba;
    else
        color = color_white;

    glColor4f(color[0], color[1], color[2], color[3]);
    R_CheckError();
}

void R_ReallocateStateArrays (int size)
{
    if (size <= r_state.array_size)
        return;
    r_state.vertex_array_3d = (GLfloat*) Mem_SafeReAlloc(r_state.vertex_array_3d, size * COMPONENTS_VERTEX_ARRAY3D * sizeof(GLfloat));
    r_state.vertex_array_2d = (GLshort*) Mem_SafeReAlloc(r_state.vertex_array_2d, size * COMPONENTS_VERTEX_ARRAY2D * sizeof(GLshort));
    r_state.color_array = (GLfloat*) Mem_SafeReAlloc(r_state.color_array, size * COMPONENTS_COLOR_ARRAY * sizeof(GLfloat));
    r_state.index_array = (GLint*) Mem_SafeReAlloc(r_state.index_array, size * COMPONENTS_INDEX_ARRAY * sizeof(GLint));
    r_state.normal_array = (GLfloat*) Mem_SafeReAlloc(r_state.normal_array, size * COMPONENTS_NORMAL_ARRAY * sizeof(GLfloat));
    r_state.tangent_array = (GLfloat*) Mem_SafeReAlloc(r_state.tangent_array, size * COMPONENTS_TANGENT_ARRAY * sizeof(GLfloat));
    r_state.next_vertex_array_3d = (GLfloat*) Mem_SafeReAlloc(r_state.next_vertex_array_3d, size * COMPONENTS_VERTEX_ARRAY3D * sizeof(GLfloat));
    r_state.next_normal_array = (GLfloat*) Mem_SafeReAlloc(r_state.next_normal_array, size * COMPONENTS_NORMAL_ARRAY * sizeof(GLfloat));
    r_state.next_tangent_array = (GLfloat*) Mem_SafeReAlloc(r_state.next_tangent_array, size * COMPONENTS_TANGENT_ARRAY * sizeof(GLfloat));
    r_state.array_size = size;
    R_BindDefaultArray(GL_VERTEX_ARRAY);
    R_BindDefaultArray(GL_COLOR_ARRAY);
    R_BindDefaultArray(GL_NORMAL_ARRAY);
    R_BindDefaultArray(GL_TANGENT_ARRAY);
    R_BindDefaultArray(GL_NEXT_VERTEX_ARRAY);
    R_BindDefaultArray(GL_NEXT_NORMAL_ARRAY);
    R_BindDefaultArray(GL_NEXT_TANGENT_ARRAY);
}

void R_ReallocateTexunitArray (gltexunit_t* texunit, int size)
{
    if (size <= texunit->array_size)
        return;
    texunit->texcoord_array = (GLfloat*) Mem_SafeReAlloc(texunit->texcoord_array, size * COMPONENTS_TEXCOORD_ARRAY * sizeof(GLfloat));
    texunit->array_size = size;
    if (!r_state.active_texunit)
        r_state.active_texunit = texunit;
    R_BindDefaultArray(GL_TEXTURE_COORD_ARRAY);
}