c3gl_fbo: added depth texture

... which is different from the depth renderbuffer

Signed-off-by: Michel Pollet <buserror@gmail.com>

diff --git a/examples/shared/libc3/srcgl/c3gl_fbo.c b/examples/shared/libc3/srcgl/c3gl_fbo.c
index 11bc385..d139bed 100644 (file)
--- a/examples/shared/libc3/srcgl/c3gl_fbo.c
+++ b/examples/shared/libc3/srcgl/c3gl_fbo.c
@@ -81,12 +81,38 @@ c3gl_fbo_create(
                GLuint rbo_depth;
                GLCHECK(glGenRenderbuffers(1, &rbo_depth));
                glBindRenderbuffer(GL_RENDERBUFFER, rbo_depth);
-               glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16,
-                               b->size.x, b->size.y);
+               GLCHECK(glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16,
+                               b->size.x, b->size.y));
                glBindRenderbuffer(GL_RENDERBUFFER, 0);
                b->buffers[C3GL_FBO_DEPTH].bid = (c3apiobject_t)rbo_depth;
        }
 
+       if (b->flags & (1 << C3GL_FBO_DEPTH_TEX)) {
+               GLuint depthTextureId;
+               glGenTextures(1, &depthTextureId);
+               glBindTexture(GL_TEXTURE_2D, depthTextureId);
+
+               // GL_LINEAR does not make sense for depth texture. However, next tutorial shows usage of GL_LINEAR and PCF. Using GL_NEAREST
+               glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+               glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+
+               // Remove artefact on the edges of the shadowmap
+               glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP );
+               glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP );
+
+               // This is to allow usage of shadow2DProj function in the shader
+               glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE, GL_COMPARE_R_TO_TEXTURE);
+               glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_FUNC, GL_LEQUAL);
+               glTexParameteri(GL_TEXTURE_2D, GL_DEPTH_TEXTURE_MODE, GL_INTENSITY);
+
+               // No need to force GL_DEPTH_COMPONENT24, drivers usually give you the max precision if available
+               glTexImage2D( GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT,
+                               b->size.x, b->size.y,
+                               0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, 0);
+               glBindTexture(GL_TEXTURE_2D, 0);
+               b->buffers[C3GL_FBO_DEPTH_TEX].bid = (c3apiobject_t)depthTextureId;
+       }
+
        /* Framebuffer to link everything together */
        GLuint fbo;
        GLCHECK(glGenFramebuffers(1, &fbo));
@@ -98,12 +124,22 @@ c3gl_fbo_create(
                // Set the list of draw buffers.
                GLenum DrawBuffers[2] = { GL_COLOR_ATTACHMENT0 };
                glDrawBuffers(1, DrawBuffers); // "1" is the size of DrawBuffers
-       } else
+       } else {
                glDrawBuffers(0, NULL); // "1" is the size of DrawBuffers
+               glDrawBuffer(GL_NONE);
+               glReadBuffer(GL_NONE);
+       }
 
        if (b->flags & (1 << C3GL_FBO_DEPTH))
                glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
                GL_RENDERBUFFER, (GLuint)b->buffers[C3GL_FBO_DEPTH].bid);
+
+       if (b->flags & (1 << C3GL_FBO_DEPTH_TEX))
+               // attach the texture to FBO depth attachment point
+               glFramebufferTexture2D(GL_FRAMEBUFFER_EXT,
+                               GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D,
+                               (GLuint)b->buffers[C3GL_FBO_DEPTH_TEX].bid, 0);
+
        b->fbo = (c3apiobject_t)fbo;
 
        GLenum status;

diff --git a/examples/shared/libc3/srcgl/c3gl_fbo.h b/examples/shared/libc3/srcgl/c3gl_fbo.h
index 2ada1cf..4bebc84 100644 (file)
--- a/examples/shared/libc3/srcgl/c3gl_fbo.h
+++ b/examples/shared/libc3/srcgl/c3gl_fbo.h
@@ -28,6 +28,7 @@
 enum {
        C3GL_FBO_COLOR  = 0,
        C3GL_FBO_DEPTH,
+       C3GL_FBO_DEPTH_TEX,
        C3GL_FBO_MAX,
 };