r_framebuffer.cpp

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/*
 Copyright (C) 2008 Victor Luchits

 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_framebuffer.h"
#include "r_error.h"

static int frameBufferObjectCount;
static r_framebuffer_t frameBufferObjects[MAX_GL_FRAMEBUFFERS];
static GLuint frameBufferTextures[MAX_GL_FRAMEBUFFERS];

static r_framebuffer_t screenBuffer;
static GLenum* colorAttachments;

static GLuint R_GetFreeFBOTexture (void)
{
    int i;

    for (i = 0; i < MAX_GL_FRAMEBUFFERS; i++) {
        if (frameBufferTextures[i] == 0) {
            glGenTextures(1, &frameBufferTextures[i]);
            return frameBufferTextures[i];
        }
    }

    Com_Error(ERR_FATAL, "Exceeded max frame buffer textures");
}

static void R_FreeFBOTexture (int texnum)
{
    int i;

    for (i = 0; i < MAX_GL_FRAMEBUFFERS; i++) {
        if (frameBufferTextures[i] == texnum)
            break;
    }

    assert(i >= 0);
    assert(i < MAX_GL_FRAMEBUFFERS);
    glDeleteTextures(1, &frameBufferTextures[i]);
    frameBufferTextures[i] = 0;
}

void R_InitFBObjects (void)
{
    if (!r_config.frameBufferObject || !r_programs->integer)
        return;

    frameBufferObjectCount = 0;
    OBJZERO(frameBufferObjects);
    OBJZERO(frameBufferTextures);

    r_state.frameBufferObjectsInitialized = true;

    float scales[DOWNSAMPLE_PASSES];
    int i;
    for (i = 0; i < DOWNSAMPLE_PASSES; i++)
        scales[i] = powf(DOWNSAMPLE_SCALE, i + 1);

    /* setup default screen framebuffer */
    screenBuffer.fbo = 0;
    screenBuffer.depth = 0;
    screenBuffer.nTextures = 0;
    screenBuffer.width = viddef.context.width;
    screenBuffer.height = viddef.context.height;
    R_SetupViewport(&screenBuffer, 0, 0, viddef.context.width, viddef.context.height);
    Vector4Clear(screenBuffer.clearColor);

    /* use default framebuffer */
    qglBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
    r_state.activeFramebuffer = &screenBuffer;

    colorAttachments = Mem_AllocTypeN(GLenum, r_config.maxDrawBuffers);
    for (i = 0; i < r_config.maxDrawBuffers; i++)
        colorAttachments[i] = GL_COLOR_ATTACHMENT0_EXT + i;

    unsigned int filters[2];
    filters[0] = GL_NEAREST;
    filters[1] = GL_LINEAR_MIPMAP_LINEAR;

    /* setup main 3D render target */
    r_state.renderBuffer = R_CreateFramebuffer(viddef.context.width, viddef.context.height, 2, true, false, filters);

    /* setup bloom render targets */
    fbo_bloom0 = R_CreateFramebuffer(viddef.context.width, viddef.context.height, 1, false, false, filters);
    fbo_bloom1 = R_CreateFramebuffer(viddef.context.width, viddef.context.height, 1, false, false, filters);

    filters[0] = GL_LINEAR;
    /* setup extra framebuffers */
    for (i = 0; i < DOWNSAMPLE_PASSES; i++) {
        const int h = (int)((float)viddef.context.height / scales[i]);
        const int w = (int)((float)viddef.context.width / scales[i]);
        r_state.buffers0[i] = R_CreateFramebuffer(w, h, 1, false, false, filters);
        r_state.buffers1[i] = R_CreateFramebuffer(w, h, 1, false, false, filters);
        r_state.buffers2[i] = R_CreateFramebuffer(w, h, 1, false, false, filters);

        R_CheckError();
    }
}


void R_DeleteFBObject (r_framebuffer_t* buf)
{
    if (buf->depth)
        qglDeleteRenderbuffersEXT(1, &buf->depth);
    buf->depth = 0;

    if (buf->textures) {
        for (int i = 0; i < buf->nTextures; i++)
            R_FreeFBOTexture(buf->textures[i]);
        Mem_Free(buf->textures);
    }
    buf->textures = 0;

    if (buf->fbo)
        qglDeleteFramebuffersEXT(1, &buf->fbo);
    buf->fbo = 0;
}


void R_ShutdownFBObjects (void)
{
    if (!r_state.frameBufferObjectsInitialized)
        return;

    for (int i = 0; i < frameBufferObjectCount; i++)
        R_DeleteFBObject(&frameBufferObjects[i]);

    R_UseFramebuffer(&screenBuffer);

    frameBufferObjectCount = 0;
    OBJZERO(frameBufferObjects);
    r_state.frameBufferObjectsInitialized = false;

    Mem_Free(colorAttachments);
}


r_framebuffer_t* R_CreateFramebuffer (int width, int height, int ntextures, bool depth, bool halfFloat, unsigned int* filters)
{
    r_framebuffer_t* buf;
    int i;

    if (!r_state.frameBufferObjectsInitialized) {
        Com_Printf("Warning: framebuffer creation failed; framebuffers not initialized!\n");
        return nullptr;
    }

    if (frameBufferObjectCount >= lengthof(frameBufferObjects)) {
        Com_Printf("Warning: framebuffer creation failed; already created too many framebuffers!\n");
        return nullptr;
    }

    buf = &frameBufferObjects[frameBufferObjectCount++];
    OBJZERO(*buf);

    if (ntextures > r_config.maxDrawBuffers) {
        Com_Printf("Couldn't allocate requested number of drawBuffers in R_SetupFramebuffer!\n");
        ntextures = r_config.maxDrawBuffers;
    }

    Vector4Clear(buf->clearColor);

    buf->width = width;
    buf->height = height;
    R_SetupViewport(buf, 0, 0, width, height);

    buf->nTextures = ntextures;
    buf->textures = Mem_AllocTypeN(unsigned int, ntextures);

#ifdef GL_VERSION_ES_CM_1_0
    buf->pixelFormat = GL_RGBA;
    buf->byteFormat = GL_UNSIGNED_BYTE;
#else
    buf->pixelFormat = halfFloat ? GL_RGBA16F_ARB : GL_RGBA8;
    buf->byteFormat = halfFloat ? GL_HALF_FLOAT_ARB : GL_UNSIGNED_BYTE;
#endif

    /* Presence of depth buffer indicates render target that could use antialiasing */
    if (depth) {
        if (qglRenderbufferStorageMultisampleEXT && qglBlitFramebuffer) {
            const int samples = r_multisample->integer;
            if (samples > 1)
                buf->samples = samples;
        }
    }

    for (i = 0; i < buf->nTextures; i++) {
        buf->textures[i] = R_GetFreeFBOTexture();
        glBindTexture(GL_TEXTURE_2D, buf->textures[i]);
        glTexImage2D(GL_TEXTURE_2D, 0, buf->pixelFormat, buf->width, buf->height, 0, GL_RGBA, buf->byteFormat, 0);

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, filters[i]);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
        glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);
        qglGenerateMipmapEXT(GL_TEXTURE_2D);
        if (r_config.anisotropic)
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, r_config.maxAnisotropic);

        R_CheckError();
    }
    glBindTexture(GL_TEXTURE_2D, 0);

    /* create FBO itself */
    qglGenFramebuffersEXT(1, &buf->fbo);
    R_CheckError();
    qglBindFramebufferEXT(GL_FRAMEBUFFER_EXT, buf->fbo);

    /* create&attach depth renderbuffer */
    if (depth) {
        qglGenRenderbuffersEXT(1, &buf->depth);
        qglBindRenderbufferEXT(GL_RENDERBUFFER_EXT, buf->depth);
        if (buf->samples)
            qglRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER_EXT, buf->samples, GL_DEPTH_COMPONENT, buf->width, buf->height);
        else
            qglRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT, buf->width, buf->height);
        qglFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, buf->depth);
    } else {
        buf->depth = 0;
    }

    /* create multisample color buffers if needed */
    if (buf->samples) {
        /* generate color buffers */
        for (i = 0; i < buf->nTextures; i++) {
            unsigned colorbuffer;
            qglGenRenderbuffersEXT(1, &colorbuffer);
            qglBindRenderbufferEXT(GL_RENDERBUFFER_EXT, colorbuffer);
            qglRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER_EXT, buf->samples, buf->pixelFormat, buf->width, buf->height);
            qglFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, colorAttachments[i], GL_RENDERBUFFER_EXT, colorbuffer);
            R_CheckError();
        }
        /* proxy framebuffer object for resolving MSAA */
        qglGenFramebuffersEXT(1, &buf->proxyFBO);
        R_CheckError();
        qglBindFramebufferEXT(GL_FRAMEBUFFER_EXT, buf->proxyFBO);
    }

    /* Whether multisampling was enabled or not, current FBO should be populated with render-to-texture bindings */
    for (i = 0; i < buf->nTextures; i++) {
        qglFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, colorAttachments[i], GL_TEXTURE_2D, buf->textures[i], 0);
        R_CheckError();
    }

    R_CheckError();

    /* unbind the framebuffer and return to default state */
    qglBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

    return buf;
}

void R_ResolveMSAA (const r_framebuffer_t* buf)
{
    if (!buf->samples)
        return;

    qglBindFramebufferEXT(GL_READ_FRAMEBUFFER_EXT, buf->fbo);
    qglBindFramebufferEXT(GL_DRAW_FRAMEBUFFER_EXT, buf->proxyFBO);
    for (int i = 0; i < buf->nTextures; i++)     {
#ifndef GL_VERSION_ES_CM_1_0
        glReadBuffer(GL_COLOR_ATTACHMENT0_EXT + i);
        glDrawBuffer(GL_COLOR_ATTACHMENT0_EXT + i);
#endif
        qglBlitFramebuffer(0, 0, buf->width, buf-> height, 0, 0, buf->width, buf->height, GL_COLOR_BUFFER_BIT, GL_NEAREST);

        R_CheckError();
    }
    R_CheckError();

    qglBindFramebufferEXT(GL_FRAMEBUFFER_EXT,  screenBuffer.fbo);
    R_CheckError();
}


void R_UseFramebuffer (const r_framebuffer_t* buf)
{
    if (!r_config.frameBufferObject || !r_programs->integer || !r_postprocess->integer)
        return;

    if (!r_state.frameBufferObjectsInitialized) {
        Com_Printf("Can't bind framebuffer: framebuffers not initialized\n");
        return;
    }

    if (!buf)
        buf = &screenBuffer;

    /* don't re-bind if we're already using the requested buffer */
    if (buf == r_state.activeFramebuffer)
        return;

    qglBindFramebufferEXT(GL_FRAMEBUFFER_EXT, buf->fbo);

    /* don't call glDrawBuffers for main screenbuffer */
    if (buf->nTextures > 0)
        qglDrawBuffers(buf->nTextures, colorAttachments);

    glClearColor(r_state.activeFramebuffer->clearColor[0], r_state.activeFramebuffer->clearColor[1], r_state.activeFramebuffer->clearColor[2], r_state.activeFramebuffer->clearColor[3]);
    glClear(GL_COLOR_BUFFER_BIT | (buf->depth ? GL_DEPTH_BUFFER_BIT : 0));

    r_state.activeFramebuffer = buf;

    R_CheckError();
}

void R_SetupViewport (r_framebuffer_t* buf, int x, int y, int width, int height)
{
    if (!buf)
        buf = &screenBuffer;

    buf->viewport.x = x;
    buf->viewport.y = y;
    buf->viewport.width = width;
    buf->viewport.height = height;
}

void R_UseViewport (const r_framebuffer_t* buf)
{
    if (!r_state.frameBufferObjectsInitialized || !r_config.frameBufferObject || !r_postprocess->integer || !r_programs->integer)
        return;

    if (!buf)
        buf = &screenBuffer;
    glViewport(buf->viewport.x, buf->viewport.y, buf->viewport.width, buf->viewport.height);
}

void R_DrawBuffers (unsigned int drawBufferNum)
{
    R_BindColorAttachments(drawBufferNum, colorAttachments);
}

void R_BindColorAttachments (unsigned int n, unsigned int* attachments)
{
    if (!r_state.frameBufferObjectsInitialized || !r_config.frameBufferObject || !r_postprocess->integer || !r_programs->integer)
        return;

    if (n >= r_config.maxDrawBuffers) {
        Com_DPrintf(DEBUG_RENDERER, "Max drawbuffers hit\n");
        n = r_config.maxDrawBuffers;
    }

    if (r_state.activeFramebuffer && r_state.activeFramebuffer->nTextures > 0)
        qglDrawBuffers(n, attachments);
}

bool R_EnableRenderbuffer (bool enable)
{
    if (!r_state.frameBufferObjectsInitialized || !r_config.frameBufferObject || !r_postprocess->integer || !r_programs->integer)
        return false;

    if (enable != r_state.renderbuffer_enabled) {
        r_state.renderbuffer_enabled = enable;
        if (enable)
            R_UseFramebuffer(fbo_render);
        else
            R_UseFramebuffer(fbo_screen);
    }

    R_DrawBuffers(1);

    return true;
}

bool R_RenderbufferEnabled (void)
{
    return r_state.renderbuffer_enabled;
}