]> de.git.xonotic.org Git - xonotic/darkplaces.git/commitdiff
added comments to the bloom code in R_BlendView to try to explain how it works
authorhavoc <havoc@d7cf8633-e32d-0410-b094-e92efae38249>
Fri, 25 Mar 2005 11:35:48 +0000 (11:35 +0000)
committerhavoc <havoc@d7cf8633-e32d-0410-b094-e92efae38249>
Fri, 25 Mar 2005 11:35:48 +0000 (11:35 +0000)
git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@5124 d7cf8633-e32d-0410-b094-e92efae38249

gl_rmain.c

index de8327286ab0c1f77f09044010b86ec4ae7e3e07..c613c66f57f452b1825fac67a82491b7ae321566 100644 (file)
@@ -600,6 +600,7 @@ static void R_BlendView(void)
        GL_DepthMask(true);
        GL_DepthTest(false);
        R_Mesh_Matrix(&r_identitymatrix);
+       // vertex coordinates for a quad that covers the screen exactly
        varray_vertex3f[0] = 0;varray_vertex3f[1] = 0;varray_vertex3f[2] = 0;
        varray_vertex3f[3] = 1;varray_vertex3f[4] = 0;varray_vertex3f[5] = 0;
        varray_vertex3f[6] = 1;varray_vertex3f[7] = 1;varray_vertex3f[8] = 0;
@@ -609,10 +610,22 @@ static void R_BlendView(void)
                int screenwidth, screenheight, bloomwidth, bloomheight, x, dobloomblend, range;
                float xoffset, yoffset, r;
                c_bloom++;
+               // set the (poorly named) screenwidth and screenheight variables to
+               // a power of 2 at least as large as the screen, these will define the
+               // size of the texture to allocate
                for (screenwidth = 1;screenwidth < vid.realwidth;screenwidth *= 2);
                for (screenheight = 1;screenheight < vid.realheight;screenheight *= 2);
+               // allocate textures as needed
+               if (!r_bloom_texture_screen)
+                       r_bloom_texture_screen = R_LoadTexture2D(r_main_texturepool, "screen", screenwidth, screenheight, NULL, TEXTYPE_RGBA, TEXF_FORCENEAREST | TEXF_CLAMP | TEXF_ALWAYSPRECACHE, NULL);
+               if (!r_bloom_texture_bloom)
+                       r_bloom_texture_bloom = R_LoadTexture2D(r_main_texturepool, "bloom", screenwidth, screenheight, NULL, TEXTYPE_RGBA, TEXF_FORCELINEAR | TEXF_CLAMP | TEXF_ALWAYSPRECACHE, NULL);
+               // set bloomwidth and bloomheight to the bloom resolution that will be
+               // used (often less than the screen resolution for faster rendering)
                bloomwidth = min(r_view_width, r_bloom_resolution.integer);
                bloomheight = min(r_view_height, bloomwidth * r_view_height / r_view_width);
+               // set up a texcoord array for the full resolution screen image
+               // (we have to keep this around to copy back during final render)
                varray_texcoord2f[0][0] = 0;
                varray_texcoord2f[0][1] = (float)r_view_height / (float)screenheight;
                varray_texcoord2f[0][2] = (float)r_view_width / (float)screenwidth;
@@ -621,6 +634,8 @@ static void R_BlendView(void)
                varray_texcoord2f[0][5] = 0;
                varray_texcoord2f[0][6] = 0;
                varray_texcoord2f[0][7] = 0;
+               // set up a texcoord array for the reduced resolution bloom image
+               // (which will be additive blended over the screen image)
                varray_texcoord2f[1][0] = 0;
                varray_texcoord2f[1][1] = (float)bloomheight / (float)screenheight;
                varray_texcoord2f[1][2] = (float)bloomwidth / (float)screenwidth;
@@ -629,28 +644,27 @@ static void R_BlendView(void)
                varray_texcoord2f[1][5] = 0;
                varray_texcoord2f[1][6] = 0;
                varray_texcoord2f[1][7] = 0;
-               if (!r_bloom_texture_screen)
-                       r_bloom_texture_screen = R_LoadTexture2D(r_main_texturepool, "screen", screenwidth, screenheight, NULL, TEXTYPE_RGBA, TEXF_FORCENEAREST | TEXF_CLAMP | TEXF_ALWAYSPRECACHE, NULL);
-               if (!r_bloom_texture_bloom)
-                       r_bloom_texture_bloom = R_LoadTexture2D(r_main_texturepool, "bloom", screenwidth, screenheight, NULL, TEXTYPE_RGBA, TEXF_FORCELINEAR | TEXF_CLAMP | TEXF_ALWAYSPRECACHE, NULL);
                memset(&m, 0, sizeof(m));
                m.pointer_vertex = varray_vertex3f;
                m.pointer_texcoord[0] = varray_texcoord2f[0];
                m.tex[0] = R_GetTexture(r_bloom_texture_screen);
                R_Mesh_State(&m);
-               // copy view to a texture
+               // copy view into the full resolution screen image texture
                GL_ActiveTexture(0);
                qglCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, r_view_x, vid.realheight - (r_view_y + r_view_height), r_view_width, r_view_height);
                c_bloomcopies++;
                c_bloomcopypixels += r_view_width * r_view_height;
                // now scale it down to the bloom size and raise to a power of itself
-               qglViewport(r_view_x, vid.realheight - (r_view_y + bloomheight), bloomwidth, bloomheight);
+               // to darken it (this leaves the really bright stuff bright, and
+               // everything else becomes very dark)
                // TODO: optimize with multitexture or GLSL
+               qglViewport(r_view_x, vid.realheight - (r_view_y + bloomheight), bloomwidth, bloomheight);
                GL_BlendFunc(GL_ONE, GL_ZERO);
                GL_Color(1, 1, 1, 1);
                R_Mesh_Draw(4, 2, polygonelements);
                c_bloomdraws++;
                c_bloomdrawpixels += bloomwidth * bloomheight;
+               // render multiple times with a multiply blendfunc to raise to a power
                GL_BlendFunc(GL_DST_COLOR, GL_ZERO);
                for (x = 1;x < r_bloom_power.integer;x++)
                {
@@ -658,7 +672,8 @@ static void R_BlendView(void)
                        c_bloomdraws++;
                        c_bloomdrawpixels += bloomwidth * bloomheight;
                }
-               // copy the bloom view to a texture
+               // we now have a darkened bloom image in the framebuffer, copy it into
+               // the bloom image texture for more processing
                memset(&m, 0, sizeof(m));
                m.pointer_vertex = varray_vertex3f;
                m.tex[0] = R_GetTexture(r_bloom_texture_bloom);
@@ -668,7 +683,7 @@ static void R_BlendView(void)
                qglCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, r_view_x, vid.realheight - (r_view_y + bloomheight), bloomwidth, bloomheight);
                c_bloomcopies++;
                c_bloomcopypixels += bloomwidth * bloomheight;
-               // blend on at multiple offsets vertically
+               // blend on at multiple vertical offsets to achieve a vertical blur
                // TODO: do offset blends using GLSL
                range = r_bloom_blur.integer * bloomwidth / 320;
                GL_BlendFunc(GL_ONE, GL_ZERO);
@@ -676,6 +691,7 @@ static void R_BlendView(void)
                {
                        xoffset = 0 / (float)bloomwidth * (float)bloomwidth / (float)screenwidth;
                        yoffset = x / (float)bloomheight * (float)bloomheight / (float)screenheight;
+                       // compute a texcoord array with the specified x and y offset
                        varray_texcoord2f[2][0] = xoffset+0;
                        varray_texcoord2f[2][1] = yoffset+(float)bloomheight / (float)screenheight;
                        varray_texcoord2f[2][2] = xoffset+(float)bloomwidth / (float)screenwidth;
@@ -684,7 +700,10 @@ static void R_BlendView(void)
                        varray_texcoord2f[2][5] = yoffset+0;
                        varray_texcoord2f[2][6] = xoffset+0;
                        varray_texcoord2f[2][7] = yoffset+0;
-                       r = r_bloom_intensity.value/(range*2+1)*(1 - fabs(x*x)/(float)(range*range));
+                       // this r value looks like a 'dot' particle, fading sharply to
+                       // black at the edges
+                       // (probably not realistic but looks good enough)
+                       r = r_bloom_intensity.value/(range*2+1)*(1 - x*x/(float)(range*range));
                        if (r < 0.01f)
                                continue;
                        GL_Color(r, r, r, 1);
@@ -693,12 +712,13 @@ static void R_BlendView(void)
                        c_bloomdrawpixels += bloomwidth * bloomheight;
                        GL_BlendFunc(GL_ONE, GL_ONE);
                }
-               // copy the blurred bloom view to a texture
+               // copy the vertically blurred bloom view to a texture
                GL_ActiveTexture(0);
                qglCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, r_view_x, vid.realheight - (r_view_y + bloomheight), bloomwidth, bloomheight);
                c_bloomcopies++;
                c_bloomcopypixels += bloomwidth * bloomheight;
-               // blend on at multiple offsets horizontally
+               // blend the vertically blurred image at multiple offsets horizontally
+               // to finish the blur effect
                // TODO: do offset blends using GLSL
                range = r_bloom_blur.integer * bloomwidth / 320;
                GL_BlendFunc(GL_ONE, GL_ZERO);
@@ -706,6 +726,7 @@ static void R_BlendView(void)
                {
                        xoffset = x / (float)bloomwidth * (float)bloomwidth / (float)screenwidth;
                        yoffset = 0 / (float)bloomheight * (float)bloomheight / (float)screenheight;
+                       // compute a texcoord array with the specified x and y offset
                        varray_texcoord2f[2][0] = xoffset+0;
                        varray_texcoord2f[2][1] = yoffset+(float)bloomheight / (float)screenheight;
                        varray_texcoord2f[2][2] = xoffset+(float)bloomwidth / (float)screenwidth;
@@ -714,7 +735,10 @@ static void R_BlendView(void)
                        varray_texcoord2f[2][5] = yoffset+0;
                        varray_texcoord2f[2][6] = xoffset+0;
                        varray_texcoord2f[2][7] = yoffset+0;
-                       r = r_bloom_intensity.value/(range*2+1)*(1 - fabs(x*x)/(float)(range*range));
+                       // this r value looks like a 'dot' particle, fading sharply to
+                       // black at the edges
+                       // (probably not realistic but looks good enough)
+                       r = r_bloom_intensity.value/(range*2+1)*(1 - x*x/(float)(range*range));
                        if (r < 0.01f)
                                continue;
                        GL_Color(r, r, r, 1);
@@ -730,7 +754,8 @@ static void R_BlendView(void)
                c_bloomcopypixels += bloomwidth * bloomheight;
                // go back to full view area
                qglViewport(r_view_x, vid.realheight - (r_view_y + r_view_height), r_view_width, r_view_height);
-               // put the original view back in place
+               // put the original screen image back in place and blend the bloom
+               // texture on it
                memset(&m, 0, sizeof(m));
                m.pointer_vertex = varray_vertex3f;
                m.tex[0] = R_GetTexture(r_bloom_texture_screen);