我想创建一个火山碎屑体积并将其存储在 3D 纹理中。当我在 CPU 上执行此操作时,这没有问题。但是由于 CPU 对我的应用程序来说很慢,所以我想借助分层渲染在 GPU 上创建 3D 纹理。
现在的问题是我的总是被零填充。没有随机数据总是为零。这就是相关代码片段目前的样子:
void init()
{
// ....
GLfloat data[] =
{
0.0f, 0.0f, 0.0f,
};
VBO = VertexBufferObject::create();
VBO->bind(GL_ARRAY_BUFFER);
VBO->setNewData(3 * sizeof(float), data, GL_STREAM_DRAW);
VBO->unbind();
glGenFramebuffers(1, &densityFBO);
glBindFramebuffer(GL_FRAMEBUFFER, densityFBO);
glGenTextures(1, &densityFBOTex);
glBindTexture(GL_TEXTURE_3D, densityFBOTex);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_REPEAT);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glTexImage3D(GL_TEXTURE_3D, 0, GL_R8, 256, 256, 32, 0, GL_RED, GL_UNSIGNED_BYTE, 0);
glBindTexture(GL_TEXTURE_3D, 0);
glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, densityFBOTex, 0);
qDebug() << glCheckFramebufferStatus(GL_FRAMEBUFFER); // returns complete
glBindFramebuffer(GL_FRAMEBUFFER, 0);
}
void createDensityTextureOnGPU()
{
glBindFramebuffer(GL_FRAMEBUFFER, densityFBO);
GLint vp[4];
glGetIntegerv(GL_VIEWPORT, vp);
glViewport(0, 0, 256, 256);
glClear(GL_COLOR_BUFFER_BIT);
shader->start();
draw();
shader->stop();
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glViewport(vp[0], vp[1], vp[2], vp[3]);
}
void draw()
{
glEnableVertexAttribArray(0);
VBO->bind(GL_ARRAY_BUFFER);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);
glDrawArrays(GL_POINTS, 0, 1);
VBO->unbind(GL_ARRAY_BUFFER);
glDisableVertexAttribArray(0);
}
和着色器:
// VERTEX
#version 440 compatibility
layout(location = 0) in vec3 vertexPosition;
out vec3 vPosition;
void main()
{
vPosition = vertexPosition;
gl_Position = vec4(vertexPosition, 1.0);
}
// GEOMETRY
#version 440 compatibility
layout (points) in;
layout (triangle_strip) out;
layout (max_vertices = 128) out;
in vec3 vPosition[1];
void main()
{
for (int i = 0; i < 32; ++i)
{
gl_Layer = i;
gl_Position = vec4(-1.0, -1.0, 0.0, 1.0);
EmitVertex();
gl_Layer = i;
gl_Position = vec4(1.0, -1.0, 0.0, 1.0);
EmitVertex();
gl_Layer = i;
gl_Position = vec4(-1.0, 1.0, 0.0, 1.0);
EmitVertex();
gl_Layer = i;
gl_Position = vec4(1.0, 1.0, 0.0, 1.0);
EmitVertex();
EndPrimitive();
}
}
// FRAGMENT
#version 440 compatibility
layout (location = 0) out float fragColor;
void main()
{
fragColor = 0.5;
}
我在做什么错/错过了什么?