2019/10/18 15:35
reflection, refraction derived
18:23 2019/10/18
Curves bezier bezier and spline distinction
bezier curves Curves
bezier spline spline or spline, bezier curve is smoothed by a multistage connected together (a common end control point)
22:14 2019/10/18
Graphics, treated with Matrix point from the space to the other space is a relatively common operation, such as conversion to the World Space Position View Space. But for NonOrthogonal matrix (non-orthogonal matrix) is, Normal after conversion is not perpendicular to it the Tangent.
gl_NormalMatrix
https://www.cnblogs.com/bigdudu/articles/4191042.html
2019/11/18 17:42
Note that the column m4x3 preference matrix indicates 4 lines 3, instead of 4 rows 3
columns of matrix M priority, multiplying the point P: Q = MXP, when the operation is to take the row by M column vector P, rather than take the M columns by row vector P
this description in OPENGL series, the default vector is a column vector
Filter (point sampling) used when the texture GL_TEXTURE_MIN_FILTER reduction (zoom out) manner
used when GL_TEXTURE_MAG_FILTER texture magnification (zoom in) Filter
2019/11/19 22:10
variable immutable texture, how it is reflected in the data on the storage
variable textures glTexImage2D to upload data
immutable textures to upload data glTexStrage2D
10:35 2019/11/22
glUniformMatrix4fv(loc, count, GL_FALSE, addr)
glUniform4fv(loc, count, GL_FALSE, addr)
Note:
a, glUniformMatrix4fv showing an 4X4 matrix
glUniformMatrix3fv represents a 3X3 matrix
glUniformMatrix4X3fv represents a 4X3 matrix (4 rows 3)
2. For matrix type, count is the number of the matrix, the non-matrix-type, count the number of points to the amount of, for example:
a float VEC [. 4] = a float [. 4] {1,2,3,4}
gluniform4fv (. 1, 1, gl_false, vec), 1 denotes a data element 4
10:42 2019/11/22
Here the original PCF, fuzzy algorithm is a variant of FIG shadow the PCF
----real time renderring 4----------------------------------------
7.5 Percentage-Closer Filtering
A simple extension of the shadow-map technique can provide pseudo-soft shadows.
This method can also help ameliorate resolution problems that cause shadows to
look blocky when a single light-sample cell covers many screen pixels. The solution is
similar to texture magnification (Section 6.2.1). Instead of a single sample being taken
off the shadow map, the four nearest samples are retrieved. The technique does not
interpolate between the depths themselves, but rather the results of their comparisons
with the surface’s depth. That is, the surface’s depth is compared separately to the
four texel depths, and the point is then determined to be in light or shadow for
each shadow-map sample. These results, i.e., 0 for shadow and 1 for light, are then
bilinearly interpolated to calculate how much the light actually contributes to the
surface location. This filtering results in an artificially soft shadow. These penumbrae
change, depending on the shadow map’s resolution, camera location, and other factors.
For example, a higher resolution makes for a narrower softening of the edges. Still, a
little penumbra and smoothing is better than none at all.
This idea of retrieving multiple samples from a shadow map and blending the
results is called percentage-closer filtering (PCF) [1475].