这让我疯了！我之前没有对OpenGL做过多少工作，所以任何指针都会受到赞赏。
任何人都可以告诉我为什么我的某些物体会出现在我的阴影贴图中，而其他物体却没有？
我有2个渲染对象; southernHemisphere和Frame。这两个都渲染到场景和阴影贴图纹理。场景正在完美地显示所有对象，但只有southernHemisphere出现在阴影贴图中。
我的阴影贴图纹理绑定如下：
- (void)setupShadowmapBuffers {
glGenTextures(1, &_shadowTexture);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, _shadowTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 1024, 1024, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glGenFramebuffers(1, &_shadowFBO);
glGenRenderbuffers(1, &_shadowRenderBuffer);
glBindRenderbuffer(GL_RENDERBUFFER, _shadowRenderBuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, 1024, 1024);
glBindFramebuffer(GL_FRAMEBUFFER, _shadowFBO);
glBindTexture(GL_TEXTURE_2D, _shadowTexture);
glFramebufferRenderbuffer(GL_FRAMEBUFFER,
GL_DEPTH_ATTACHMENT,
GL_RENDERBUFFER,
_shadowRenderBuffer);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, _shadowTexture, 0);
if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
{
printf("Error: FrameBufferObject is not complete!\n");
}
}
在我的渲染功能中，我渲染到阴影贴图纹理：
// Render the shadow map
glUseProgram(_shadowProgramHandle);
glUniformMatrix4fv(_shadowProjectionUniform, 1, 0, LSprojection.glMatrix);
glUniformMatrix4fv(_shadowLightMPVUniform, 1, 0, lightsourcemat.glMatrix);
glBindFramebuffer(GL_FRAMEBUFFER, _shadowFBO);
glBindRenderbuffer(GL_RENDERBUFFER, _shadowRenderBuffer);
glClearColor(0,0,0,0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glViewport(0, 0, 1024, 1024);
glUniformMatrix4fv(_shadowModelViewUniform, 1, 0, southernHemispheremat.glMatrix);
[self drawSouthernHemisphere];
glUniformMatrix4fv(_shadowModelViewUniform, 1, 0, framemat.glMatrix);
[self drawFrame];
然后我渲染到场景：
// Reset buffers and finally render the scene
glUseProgram(_mainProgramHandle);
glBindFramebuffer(GL_FRAMEBUFFER, msaaFramebuffer);
glBindRenderbuffer(GL_RENDERBUFFER, msaaRenderBuffer);
glClearColor(0,0,0,0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glViewport(0, 0, vFrame.size.width, vFrame.size.height);
glUniformMatrix4fv(_modelViewUniform, 1, 0, shadowmat.glMatrix);
[self drawShadow];
glUniformMatrix4fv(_modelViewUniform, 1, 0, southernHemispheremat.glMatrix);
[self drawSouthernHemisphere];
glUniformMatrix4fv(_modelViewUniform, 1, 0, framemat.glMatrix);
[self drawFrame];
我的绘图功能如下所示：
- (void)drawSouthernHemisphere {
// Southern Hemisphere
glEnable(GL_CULL_FACE);
glBindTexture(GL_TEXTURE_2D, _globeTexture);
glBindVertexArrayOES(_southernHemisphere);
// Draw outside (textured)
glUniform1f(_useTextureSlot, 1);
glCullFace(GL_BACK);
glDrawElements(GL_TRIANGLES, sizeof(Southern)/sizeof(Southern[0]), GL_UNSIGNED_SHORT, 0);
// Draw inside (coloured)
glCullFace(GL_FRONT);
glUniform1f(_useTextureSlot, 0);
glUniform4f(_runTimeColorSlot, 0, 0, 0, 0);
glDrawElements(GL_TRIANGLES, sizeof(Southern)/sizeof(Southern[0]), GL_UNSIGNED_SHORT, 0);
glBindVertexArrayOES(0);
}
- (void)drawFrame {
// Frame
glEnable(GL_CULL_FACE);
glBindTexture(GL_TEXTURE_2D, _frameTexture);
glBindVertexArrayOES(_frame);
// Draw outside (textured)
glUniform1f(_useTextureSlot, 1);
glCullFace(GL_BACK);
glDrawElements(GL_LINES, sizeof(Frame)/sizeof(Frame[0]), GL_UNSIGNED_SHORT, 0);
glBindVertexArrayOES(0);
}
感谢。
修改
我已将问题分离到我的顶点数组 - 特别是法线。
我将frame数组中的值与我的southernHemisphere数组中的值进行了交换，并且bingo - 该对象同时出现在场景和阴影贴图中！
经过一些值的调整后，它似乎只有在法线的方向与每个矢量本身的方向相同时才有效。
令我感到困惑的是，在我的阴影贴图中，我甚至没有访问法线，所以为什么它们对渲染有任何影响？
这是我的阴影贴图的顶点着色器：
attribute vec4 Position;
uniform mat4 Projection;
uniform mat4 Modelview;
uniform mat4 Light;
varying vec4 TexCoord;
void main()
{
TexCoord = Projection * Light * Modelview * Position;
gl_Position = Projection * Light * Modelview * Position;
}
和片段：
precision mediump float;
varying vec4 TexCoord;
void main()
{
/* Generate shadow map - write fragment depth. */
float value = 10.0 - TexCoord.z;
float v = floor(value);
float f = value - v;
float vn = v * 0.1;
gl_FragColor = vec4(vn, f, 0.0, 1.0);
}
EDIT2：
以下是我为VAO设置的功能
// Southern Hemisphere
glGenVertexArraysOES(1, &_southernHemisphere);
glBindVertexArrayOES(_southernHemisphere);
GLuint vb2;
glGenBuffers(1, &vb2);
glBindBuffer(GL_ARRAY_BUFFER, vb2);
glBufferData(GL_ARRAY_BUFFER, sizeof(Vertices), Vertices, GL_STATIC_DRAW);
glEnableVertexAttribArray(_positionSlot);
glVertexAttribPointer(_positionSlot, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Position));
glEnableVertexAttribArray(_colorSlot);
glVertexAttribPointer(_colorSlot, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Color));
glEnableVertexAttribArray(_normalSlot);
glVertexAttribPointer(_normalSlot, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Normal));
glEnableVertexAttribArray(_texCoordSlot);
glVertexAttribPointer(_texCoordSlot, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, TexCoord));
GLuint southernBuffer;
glGenBuffers(1, &southernBuffer);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,southernBuffer);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(Southern) * sizeof(Southern[0]), Southern, GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArrayOES(0);
// Frame
glGenVertexArraysOES(1, &_frame);
glBindVertexArrayOES(_frame);
GLuint vb4;
glGenBuffers(1, &vb4);
glBindBuffer(GL_ARRAY_BUFFER, vb4);
glBufferData(GL_ARRAY_BUFFER, sizeof(Frame_Vertices), Frame_Vertices, GL_STATIC_DRAW);
glEnableVertexAttribArray(_positionSlot);
glVertexAttribPointer(_positionSlot, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Position));
glEnableVertexAttribArray(_colorSlot);
glVertexAttribPointer(_colorSlot, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Color));
glEnableVertexAttribArray(_normalSlot);
glVertexAttribPointer(_normalSlot, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Normal));
glEnableVertexAttribArray(_texCoordSlot);
glVertexAttribPointer(_texCoordSlot, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, TexCoord));
GLuint legsBuffer;
glGenBuffers(1, &frameBuffer);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,frameBuffer);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(Frame) * sizeof(Frame[0]), Frame, GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArrayOES(0);
我的阵列都遵循相同的形式：
const Vertex Vertices[] = {
{{0.0000,-1.5000,0.0000},{0.3843137254902,0.14117647058824,0.082352941176471,1},{0.0000,-1.0000,0.0000},{0.0000,1.0000}},
{{0.0000,-1.4872,0.1958},{0.3843137254902,0.14117647058824,0.082352941176471,1},{0.0000,-0.9914,0.1305},{0.0000,0.9583}},
....
}
由位置，颜色，法线，纹理坐标组成，如设置代码所示。
在我的着色器链接后，我完成了以下设置：
- (void)useMainProgram:(GLfloat[])lightsource {
const GLfloat l_ambient = 0.7;
glUseProgram(_mainProgramHandle);
_positionSlot = glGetAttribLocation(_mainProgramHandle, "Position");
_colorSlot = glGetAttribLocation(_mainProgramHandle, "Color");
_normalSlot = glGetAttribLocation(_mainProgramHandle, "Normal");
_lightingSlot = glGetUniformLocation(_mainProgramHandle, "l1");
_ambientLightingSlot = glGetUniformLocation(_mainProgramHandle, "l_ambient");
_texCoordSlot = glGetAttribLocation(_mainProgramHandle, "TexCoordIn");
_useTextureSlot = glGetUniformLocation(_mainProgramHandle, "use_texture");
_runTimeColorSlot = glGetUniformLocation(_mainProgramHandle, "RunTimeColor");
glEnableVertexAttribArray(_positionSlot);
glEnableVertexAttribArray(_colorSlot);
glEnableVertexAttribArray(_normalSlot);
glEnableVertexAttribArray(_texCoordSlot);
_projectionUniform = glGetUniformLocation(_mainProgramHandle, "Projection");
_modelViewUniform = glGetUniformLocation(_mainProgramHandle, "Modelview");
for (int i=0;i<_num_bottles; i++){
_bottlesUniform[i] = glGetUniformLocation(_mainProgramHandle, "Modelview");
}
_textureUniform = glGetUniformLocation(_mainProgramHandle, "Texture");
// Lighting doesn't change, so we set it here.
glUniform3fv(_lightingSlot, 1, lightsource);
glUniform1fv(_ambientLightingSlot, 1, &l_ambient);
}
- (void)useShadowProgram:(GLfloat[])lightsource {
glUseProgram(_shadowProgramHandle);
_shadowPositionSlot = glGetAttribLocation(_shadowProgramHandle, "Position");
_shadowLightMPVUniform = glGetUniformLocation(_shadowProgramHandle, "Light");
_shadowProjectionUniform = glGetUniformLocation(_shadowProgramHandle, "Projection");
_shadowModelViewUniform = glGetUniformLocation(_shadowProgramHandle, "Modelview");
glEnableVertexAttribArray(_shadowPositionSlot);
}