Failed to generat the shadow map

OpenGL Development
#1

I’ve been struggling with the shadow mapping for two days (with JOGL), yet still couldn’t make it work. Now I just want to render a very simple shadow map (grass), where closer looks brighter and further looks darker, from the view of the light point.

Here is my code:


//setting up buffers
gl.glGenFramebuffers(1, framebuff);
gl.glBindFramebuffer(GL4.GL_FRAMEBUFFER, framebuff.get(0));

gl.glGenTextures(2, textureBuff);
gl.glBindTexture(GL4.GL_TEXTURE_2D, textureBuff.get(0));
gl.glTexStorage2D(GL4.GL_TEXTURE_2D, 1, GL4.GL_R32F, displayWidth, displayHeight);
gl.glTexParameteri(GL4.GL_TEXTURE_2D, GL4.GL_TEXTURE_MAG_FILTER, GL4.GL_LINEAR);
gl.glTexParameteri(GL4.GL_TEXTURE_2D, GL4.GL_TEXTURE_MIN_FILTER, GL4.GL_LINEAR_MIPMAP_LINEAR);
gl.glFramebufferTexture(GL4.GL_FRAMEBUFFER, GL4.GL_COLOR_ATTACHMENT0, textureBuff.get(0), 0);

gl.glBindTexture(GL4.GL_TEXTURE_2D, textureBuff.get(1));
gl.glTexStorage2D(GL4.GL_TEXTURE_2D, 1, GL4.GL_DEPTH_COMPONENT32F, displayWidth, displayHeight);
gl.glTexParameteri(GL4.GL_TEXTURE_2D, GL4.GL_TEXTURE_MAG_FILTER, GL4.GL_LINEAR);
gl.glTexParameteri(GL4.GL_TEXTURE_2D, GL4.GL_TEXTURE_MIN_FILTER, GL4.GL_LINEAR_MIPMAP_LINEAR);
gl.glTexParameteri(GL4.GL_TEXTURE_2D, GL4.GL_TEXTURE_COMPARE_MODE, GL4.GL_COMPARE_REF_TO_TEXTURE);
gl.glTexParameteri(GL4.GL_TEXTURE_2D, GL4.GL_TEXTURE_COMPARE_FUNC, GL4.GL_LEQUAL);
gl.glFramebufferTexture(GL4.GL_FRAMEBUFFER, GL4.GL_DEPTH_ATTACHMENT, textureBuff.get(1), 0);
gl.glDrawBuffer(GL4.GL_NONE);

if(gl.glCheckFramebufferStatus(GL4.GL_FRAMEBUFFER) != GL4.GL_FRAMEBUFFER_COMPLETE)
			System.out.println(gl.glCheckFramebufferStatus(GL4.GL_FRAMEBUFFER));

drawing command (not sure if it’s correct):


//gl.glBindFramebuffer(GL4.GL_FRAMEBUFFER, framebuff.get(0));
gl.glViewport(0, 0, displayWidth, displayWidth);
gl.glEnable(GL4.GL_POLYGON_OFFSET_FILL);
gl.glPolygonOffset(2.0f, 4.0f);

/*
gl.glClearBufferfv(GL4.GL_COLOR, 0, new float[] {0, 0, 0}, 0);
gl.glClearDepth(1.0f);
gl.glClear(GL4.GL_DEPTH_BUFFER_BIT);*/

setupMVPMatrix();
gl.glBindVertexArray(vaoBuff.get(0));

gl.glUseProgram(shaderProgram);
gl.glDrawArraysInstanced(GL4.GL_TRIANGLE_STRIP, 0, 5, 512 * 512);

gl.glDisable(GL4.GL_POLYGON_OFFSET_FILL);
//gl.glBindFramebuffer(GL4.GL_FRAMEBUFFER, 0);

when I comment the glBindFramebuffer(), the grass appears correctly with the white color (from the light point of view, which shows the matrix should be correct).
But if I call glBindFramebuffer() with depth test enabled, everything just disappeared while I expect the closer grass to be brighter and further grass to be darker. I have also checked the framebuffer status, yet it seems there is no error. Any help?

Fixed, I didn’t understand the meaning of off-screen rendering at the beginning. Just render the depth value into the default framebuffer for display with the texture storing the depth value, and everything work just fine.

#2

what actually is rendered? Can you show the shadow texture itself? And what does your shader code look like?

#3

I just followed the tutorial here http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-16-shadow-mapping/
And I was trying to achieve that gray texture showed before using the shadow map on that tutorial. The shader code is exactly the same. I just want to know the drawing commands that is suppose to achieve that gray texture (not for that geometry shape, but to render something on the screen).

#4

If there aren’t any errors then you probably are drawing to the frame buffer correctly, everything should disappear (no longer drawing to the screen, but to a texture).

Now what I don’t see is a place where you render the textures drew to the framebuffer.

#5

Yeah, I just realized that. But how, I checked the blue book yet I did not find the code of that part.

#6

You might be overthinking this, have you ever drawn a texture on an object?

set an active texture, bind the texture you want to use, textureBuff.get(0) should have the color info, draw a plane with proper uv coords (and no lighting applied), and done.

#7

Fixed finally. God, it took me 5 days. Thank you very much.

#8

No problem! ;D